Basic Pig Husbandry Practices

Housing and Facilities

The farrowing pen is the most vital part of the farm. Its design must ensure optimal temperature conditions for the sow and her offspring for the initial seven to ten days following delivery, with minimal emphasis on trampling and overlying. A farrowing house, a sizable chamber outfitted with five or six farrowing cages, is recommended.

The length of a five-pen house is 13.25 metres, while a six-pen house is 15.5 metres. The breadth should be 4 metres in both instances. Each pen will have a feed passage measuring 1 m on the northern side and an excrement passage of 1 m on the southern side. Each pen will measure 2 x 2.25 m. A distance of 1 metre must exist between the exterior wall and the first enclosure, with the entrance situated on the short side of the structure. The area is connected to the dung and feed passages. The diagram presented on the subsequent page depicts the configuration of a conventional farrowing crate. Sows housed in farrowing crates
Every pen is required to have a farrowing crate, in which the sow remains from one week before the birth of the piglets until they are 28 or 35 days old, at which point they are weaned. The cargo is positioned within the enclosure, with a 1.5-metre-wide by 1-metre-wide gap on one side. The water and feed receptacle (500 mm in length and 200 mm in height) are located on the feed passage side of the enclosure. A water nozzle may be positioned above the feeding receptacle if water is applied in the farrowing house.
The entrance gate is adjacent to the dung passageway. A creep area for the infants must be provided. A 600 x 600 mm receptacle made of steel or wood, large enough to accommodate the refuse, may be positioned adjacent to the feed trough and the feed passage wall. The creep is crucial because it contributes to reducing crushing-related fatalities.
Additionally, it furnishes a draft-free space for the piglets to exchange body heat. The creep area ensures that piglets maintain a temperature range of 27 to 32 °C for the initial ten days of their lives. For ventilation and cooling purposes, the farrowing house must have apertures along both sides (on the lengthy wall sides). The ideal operating temperature for the farrowing receptacle housing the sow should not exceed 21 degrees Celsius.

Based on the physiological and behavioural requirements of pigs, it is possible to identify three crucial welfare concerns for sows and piglets:

Room and liberty of movement.
A pleasant climate.
Nest construction.

A. Space and Freedom to Move

Figure 11.6 Duroc Farrowing pen of sows

Sows worldwide, including those in South Africa, are confined in containers during farrowing and lactation, providing minimal space for movement. This confinement, which conserves space and simplifies manure management, can induce stress and frustration in sows, leading to complications such as protracted labour, increased risk of stillbirths, and postnatal mortality in piglets. Musculoskeletal complications may also arise due to physical confinement, affecting thermoregulation and social development. Inadequate space surrounding the mammary during suckling can cause teat battling and an unstable teat order, resulting in injuries and stunted growth in infants. Despite its practical benefits, creating raises significant welfare concerns for both sows and offspring.

B. Convenient Climate

The contrasting thermal requirements of calves and sows influence the environment within farrowing units. The thermo-neutral zone of sows is between 16 and 20 °C, beyond which they increase respiration rate to calm down. The act of creating sows hinders their behavioural regulation of body temperature, rendering them more susceptible to heat stress. This sensitivity may be exacerbated by the increased heat generated during milk production by sizable litter. On the contrary, neonatal piglets exhibit susceptibility to low temperatures, requiring a critical ambient temperature to exceed 34 °C. Their inadequate heat production mechanisms render them susceptible to hypothermia, especially during the initial hours of existence. Low farrowing room temperatures (22 to 24 °C) fall below the critical temperature, giving rise to prevalent instances of hypothermia at birth. This condition can be fatal due to a multitude of factors. Piglets have a wider thermo-neutral zone following the initial critical day; however, hypothermia continues to result in stunted growth and elevated mortality rates.

C. Nest Construction

Sows possess a robust instinct to construct nests before parturition, which is stimulated by hormonal fluctuations. Sows display nesting behaviour towards floor and pen fittings even in environments devoid of bedding and slatted floors, where nesting is not environmentally feasible. According to research, tension and frustration caused by preventing nesting behaviour can result in complications during farrowing, including an increased risk of stillbirth, protracted labour, and diseases such as MMA or PDS. An entirely constructed nest from materials such as straw ensures optimal thermal conditions, averts hypothermia in piglets, and fosters their development. In addition to preventing injuries, a plush floor surface constructed from nest materials allows piglets to engage in exploration. Nevertheless, nest and bedding materials are frequently absent in commercial pig production, which deprives sows and piglets of these vital nutrients.

Weighing of Pigs, Record Data and Reporting

A. Correct Time to Weigh Pigs

Pork producers who employ birth weights as a component of their managerial framework may integrate the weighing procedure during the processing of piglets. Although not all piglets are weighed at birth, this step should be completed before proceeding with the remaining processing steps. Certain producers weigh and register the sex and weight of each piglet. Others weigh the litter in its entirety and record the total weight of the litter on scales. Besides weighing with a scale, the weight of a pig can be approximated using two of its body measurements and the following formula:

LW = HG² x L x 69.3

The approximation of a pig’s live weight (LW) involves the heart girth (HG) and length (L)

Example:

A pig has the following measurements:

HG = 1.27 metres
L = 1.02 metres

LW = 2.17² x 1.02 x 69.3 = 114 kg

This procedure is reported to be accurate to within 3%.

Liveweight vs deadweight:

The equation above yields the live weight of the pig. Although the exact conversion from liveweight to deadweight can differ slightly, a 72% ratio is a reasonable approximation. Therefore, the carcass weight of the pork pig in our example would be approximately 82 kilograms (114 kg x 0.72).

B. Operating a Weighing Scale

The utilisation of data obtained from weight monitoring can be implemented for a multitude of objectives, which encompass:

Estimating feed quantities
Adjusting weaning weights
Measuring animal growth to herd condition
Production and efficiency
Monitoring pregnancy, health, nutrition and genetics

Weighing methods must be precise for commercial livestock to maintain productivity and flourish. The weight of the inputs used in pig production, including reproduction, weaning, developing, and completing, is a primary determinant. Monitoring weight is the most effective way to ensure that your animal is adequately hydrated with water and has sufficient protein and energy to meet nutritional requirements, which serves as a performance metric.

Advantages of weighing scales for portable livestock:

Scales assessing livestock could be among the most crucial investments for herd-sized producers. Before going to market, precise weighing guarantees the highest possible return on each animal. Accurate scales are a critical requirement to enhance the operation’s productivity and efficiency significantly. Profits must be maximised using a precise metering apparatus. Livestock scales facilitate the consistent and precise acquisition of measurements, particularly when they are appropriately calibrated and maintained.

Accurate weighing of pigs

Farm administrators and livestock farmers need not look beyond Osborne’s to ensure the precision and accuracy of the data they acquire regarding their herds. Long service life and consistent precision are hallmarks of the ACCU-ARM Scales manufactured by Osborne. These animal-friendly scales rapidly and precisely measure the mass of livestock in various environments. The scale is entirely cable-free, whether in testing facilities or for commercial production, due to its system of precision levers that eliminate oscillation and vibration. A network of sway bars reduces the scale’s movement, which significantly improves the accuracy of livestock weighing (to less than 1% with a digital scale metre) and substantially reduces tension for the animals and the individuals performing the weighing.

Additionally, the portable ACCU-ARM Scale from Osborne is extensively used on the livestock show circuit. For decades, livestock displays, county fairs, 4-H organisations, and the like have used ACCU-ARM Scales due to their precision when weighing show pigs, lambs, goats, and calves.

C. Recording Weighing Data

Pork producers should utilise production records to identify operational strengths and limitations. The perpetuation of issues encountered in the farrowing quarters can be ensured through the failure to maintain accurate records. Recognising the heritability of reproductive traits is crucial. Maintaining records enables the identification and retention of superior sows on the farm. This will result in a series of enhancements in lactational performance, which ought to mitigate challenges in the farrowing quarters.

Additionally, accurate records provide a crucial assessment of the animal caretaker’s job performance. Records aid in identifying individuals whose performance merits recognition (and possible rewards) and pinpointing areas of weakness that require improvement by the custodian.

Birth date, number of piglets born alive and deceased, date and cause of death of piglets, pedigree information, number of piglets weaned, and piglet (or litter) weaning weight are among the records maintained in the farrowing quarters. Additionally, any abnormal or flawed characteristics of the piglet should be noted. Additionally, a growing number of producers monitor feed ingestion throughout lactation. A record of all medications administered to animals is required to assure adherence to treatment protocols and withdrawal periods.

Place recording devices such as cards, clipboards, or similar equipment near each farrowing crate or enclosure. Ensuring accuracy is achieved by having the capability to record information as soon as it is observed or collected. It is essential to carry a stylus or pen at all times, along with the necessary processing apparatus for piglets. Utilise ink to record data whenever feasible and feasible. This improves the legibility of the forms and increases the ink’s resistance to the conditions of the farrowing quarters. Additionally, ensure that data is recorded in legible handwriting, and if multiple individuals regularly collaborate in the farrowing quarters, establish the practice of including your initials next to each entry.

Boar Management Practices

A. Breeding

Large white boar for breeding

Before mating:

Appropriate management and nutrition are required before and throughout the reproductive season. This includes capacity for nutrition, accommodation, healthcare, and services. When effective management practices are not adhered to, the outcomes obtained from a boar frequently fall short of expectations. His ration should be increased to 2.7 kg six to eight weeks before the reproductive season to condition the pig.

A fertility test should be performed at least 30 days before using the pig. One effective method is to hand-make him with five to six virgin gilts in good health that are slated for slaughter. The fecundity of the boar could be called into doubt if, within 28 days of mating, more than one-third of these gilts return to heat. He ought to be evaluated by an individual with the requisite porcine assessment expertise.

An assessment of the reproductive organs’ maturation and anatomy should be incorporated into the evaluation.
An evaluation of the individual’s capacity to achieve a healthy erection, which is succeeded by a normal penile extension and the delivery of a satisfactory service.
Motility, concentration, and morphological and anatomical abnormalities of the sperm are evaluated.

During periods of high temperature (27 degrees Celsius or higher), manual reproduction should occur either early in the morning or late at night. It is preferable to feed the boar once per day, after its utilisation. Ideally, at least two breeds should occur during the heat period on the sow: late on the first day and early on the second. According to research, two services increase litter size by one pig and conception by 30% during the first heat.

The determination of the typical reproductive burden for boars is challenging due to the variability observed in libido, aggression, and physical prowess among individual boars. Based on research and practical experience, the recommendations above are merely approximations and should be cautiously utilised. For optimal fertility and grouped farrowing, maintain one boar for every two sows weaned on a given day or stagger weaning in multiple farrowing units.

Mating procedure:

The practice of hand coupling is more prevalent among pigs than among cattle or sheep. Indeed, it is virtually an established protocol within purebred pig colonies, and certain commercial producers also adhere to this methodology.

A breeding crate is advised when a mature, weighty boar is mated to gilts or when a boar pig is to be bred to large, rugous sows. Naturally reproducing animals may exhibit resistance to crate service or breed with hesitancy. In the absence of a breeding container, two bundles of hay positioned on each side of a gilt could be an adequate replacement.

In situations involving field mating with commercial livestock, the following two approaches are advised:

Divide the livestock among the groups, assigning one pig to each.
One boar or set of boars should be utilised in the livestock one day, and another boar or set of boars should be utilised the following day.

Permitting the boars in breeding enclosures to be outside during the day and from sunset to sunrise during the summer months can result in the best conception rates.

Mating age for boar.

Age in months	Pasture mating	Hand mating
Up to 7	None	None
7 to 9	6 to 8 in 21 days	10 to 15 in 21 days
9 to 12	8 to 10 in 21 days	15 to 20 in 21 days
12 to 18	10 to 12 in 21 days	20 to 25 in 21 days
18 and higher	12 to 15 in 21 days	25 to 30 in 21 days

B. Boar Care Outside of the Reproductive Season

It is customary to confine boars of identical age and stature during the interbreeding period on the condition that they are introduced to one another at a young age and maintain well-groomed tusks. The tusks of senior boars should be extracted annually before the onset of the mating season or as required. Tools such as bolt cutters, hoof trimmers, or a hack saw are appropriate for completing this task. Herdsmen may be spared severe injury by maintaining trimmed canines. Angry adult boars frequently launch attacks when the opportunity presents itself.

It is advisable to exercise patience and sound judgement when managing the reproductive animals, as mistreatment can potentially instil viciousness in older boars or induce extreme timidity in young boars, preventing them from readily mating when the occasion arises.

Boars that are not acquainted with one another should not be grouped.
Ensure that living quarters protect against severe weather.
Provide sufficient shade; in the absence of natural shadow, ensure the provision of a minimum of 30 square feet of artificial shade.
Provide at least 0.1 hectare of exercise area, preferably comprised of legume pasture. Active participation in outdoor exercise throughout the year is a fundamental requirement for maintaining the boar’s health and vigour.
To promote physical activity, designate distinct areas for feeding and sleeping. A receptacle that is marginally smaller in size can be positioned alongside the pig. This typically stimulates the boar to begin consuming by providing competition during feeding time and promoting physical activity.

C. Transporting Boars

Transport the boar with extra caution to prevent illness and injury. Even with proper care and administration, he should not be utilised for at least 30 days after an isolation period. Observe the following considerations when replacing reproductive herds:

Possess adequate loading and discharging facilities.
Ensure a thorough cleaning and disinfection of the lorry.

D. Procedures for New Boars

Furnishing appropriate bedding materials, such as straw, debris, grit, etc, is imperative.

Offer safeguarding against wind, extreme weather, precipitation, snow, or heat.
Boars unfamiliar with one another or overfed before being hauled should not be grouped, particularly during sweltering weather.
Once you have brought the boar home, isolate him.

Comfortable facilities free of drainage from other properties and isolated from all other animals should be provided for the new boar. The subsequent actions ought to be executed:

After a few weeks, clean and disinfect the quarters before introducing the new boar into the household.
Provide a well-ventilated, dry, draft-free sleeping area measuring 4.6 to 6 square metres.
The boar should not be positioned adjacent to a gilt enclosure. Sleeping adjacent to the fence while outdoors may expose him to potential respiratory complications.
Reisolate and retest the newly acquired boar from the herd for at least 30 days during a confinement operation.

E. Replacement of Boars

Boars must be replaced when they become too large to serve most of the sows on the farm.
Boars usually have a maximum working life of between 18 and 24 months. This means they should be replaced when they are 30 to 36 months old.
It is very important to keep a record of the boar’s use so that infertile ones can be detected and replaced as soon as possible.
A low sex drive (libido) can also be a problem. Some boars are slow workers and are sometimes reluctant and only

F. Feeding of Boars

Limited quantities of practical agricultural provisions contain any nutrient in sufficient deficiency to impede the reproductive function of a boar. Nonetheless, prolonged feeding of a boar with a regimen that is inadequate in both quantity and balance of nutrients may result in either permanent or temporary sterility. The majority of breeders have a propensity to overfeed a pig. Engaging in this wasteful practice will lead to fatigue, diminished libido, and over-finishing.

A balanced 14% ration (1.8 to 2.2 kgs) of maise and 0.22 kg of a 35% protein supplement should be provided to the young boar. This quantity may need to be adjusted during the reproductive season if he is over or under-conditioned to preserve his vigour and thriftiness. Young boars that are in optimal reproductive condition typically require 3 kg of feed for the initial breeding season and can be adequately maintained on 1.5 kg of feed when not being utilised.

G. Healthcare and Examination

The majority of health issues can be managed by purchasing boars from populations that appear to be disease—and parasite-free. Typically, this can be ascertained through a meticulous inspection of the livestock and premises before purchasing a pig.

After bringing the boar into your household, isolate him for as long as possible; eight to ten weeks is ideal. To ensure your boar’s and livestock’s health, you should consult your veterinarian and utilise his or her services as necessary.

The following are consumer health recommendations:

Before purchasing a piglet, a negative brucellosis test and leptospirosis vaccination are required.
Confirm that the boar has received an erysipelas vaccination.
If the owner has not recently been treated for internal and external parasites, perform such procedures.
During the period of isolation, closely monitor the boar for indications of illness, lethargy, or wheezing. If his body temperature exceeds 39 °C, have him examined by a veterinarian.
After bringing him home, obtain a blood test for brucellosis and leptospirosis three to four weeks later. As a precaution, verify that he has not contracted any of these diseases on route to your farm or immediately before the purchase. Have your veterinarian conduct a thorough examination of him while he is isolated.
If the boar develops an exceptionally high temperature and becomes ailing, refrain from using him for eight to ten weeks or until the fever has subsided.
Implement the most effective sanitation and health programme possible to ensure the health and vitality of the herd boar.
To determine whether a disease is being suppressed, all antibiotics must be eliminated from the diet for one month before reproduction or three weeks after arrival.
After three weeks of isolation and three to one month before reproduction, rotate the new boar through the sow lot. Allow the new boar to range alongside bred sows or in spaces used by sows to be bred to him to acquaint him with the health conditions prevalent in your herd before breeding.

Abnormalities in Sows, Boars and Piglets.

Abnormalities are deviations from typical development that can affect any internal or external organ of the pig. These abnormalities can potentially hinder the piglets’ functionality or even result in their demise. Abnormalities or defects of the anatomy manifest in at least 1% of piglets upon birth. The defects mentioned above could potentially arise from genetic or environmental influences. While the occurrence of these flaws is uncommon, they have the potential to be significant economic losers within a single cohort.

Historically, manufacturers have postulated that all anomalies stemmed from genetic factors due to the conspicuous and congenital nature of the defects. The term “congenital defects” solely denotes their visibility at birth and does not indicate a genetic origin. It is currently acknowledged that environmental factors, including viral infections, dietary deficiencies, and the consumption of specific medications, chemicals, and pesticides while pregnant, have the potential to disrupt the regular prenatal development of pigs. Indeed, certain instances of an anomaly may be attributed exclusively to environmental factors, whereas alternative instances of the identical anomaly may arise from genetic influences.

Abnormalities in sows and boars

A. Causes of Abnormality

When an anomaly arises, it is the producer’s responsibility to impartially determine its origin. The responses to subsequent inquiries may aid in ascertaining whether the anomaly is inherited.

Did the defective animals originate from a single breed or sire? In general, the occurrence of an abnormality in multiple breeds, sire progeny groups (when the sires are unrelated), crossbred populations (but not the contributing purebred populations), or in a crossbred population without any correspondence to the contributing purebred populations renders its genetic origin improbable.
Does the condition affect each progeny if observed in the descendants of a single sire? Thoroughly examine the lineages of the mothers from every offspring. If the majority of affected litters originate from half-sister mothers, a genetic cause should be suspected. Consider environmental factors if the defect is present in nearly every litter produced by an unrelated pair of mothers and the boar carries it; otherwise, dominant gene action is assumed, and the boar would have developed the defect by now.
Does the anomaly manifest in litters resulting from inbreeding between closely related animals? Inbreeding increases the prevalence of traits induced by recessive alleles being expressed. Although inbreeding with selection can decrease the prevalence of recessive genes, advancements will be sluggish if the recessive gene’s initial frequency is low.
Were the affected litters subjected to comparable environmental, nutritional, and management conditions during gestation? Suppose the affected litters were born within the same period, and litters born at different times, sired by the same boar and from females of comparable pedigree, did not exhibit the condition. In that case, it is improbable that a genetic factor is the cause.

B. Type of Genetic Mechanisms

Knowledge of the precise genetic mechanism that causes a genetic abnormality will assist livestock producers in devising strategies to eradicate the issue from their herd. Possible genetic disorder causes include chromosomal deviances. Chromosomes are threadlike structures that transport genetic information within the nucleus of a cell. Pairs of chromosomes are present in body cells. Each ovum and sperm contain a single copy of each chromosome pair. Two varieties of chromosomes exist. Sex chromosomes refer to a specific pair of chromosomes that are implicated in the determination of an animal’s sex. In mammals, the X and Y chromosomes represent the sexes; the X chromosome is considerably larger than the Y chromosome. Males possess one X and one Y chromosome, whereas females possess two X chromosomes. Autosomal chromosomes refer to all chromosomes besides those associated with sex.

Whether the number of chromosome pairs in pigs increased or decreased relative to the norm (19 pairs). When the number of chromosomes is increased or decreased, the consequences are frequently so severe as to induce premature embryonic mortality. An increase in the quantity of sex chromosomes is the only exception; this typically leads to infertility.
Secondly, structural modifications. Common causes of structural alterations include the fragmentation and aberrant reassembly of chromosomal segments that occur during sperm or egg formation. These defects frequently lead to significant abnormalities, which frequently culminate in fatal demise or premature mortality of the neonatal piglets. Nevertheless, European data indicates that certain translocations—the transfer of chromosomal segments to another chromosome—do not result in fatality for certain hogs but may reduce the fertility of boars. One that is piercing Litter size reduction among sows that have been mated to a particular boar may serve as an indication that the boar has undergone a translocation.
Chromosomal disorders in pigs

C. Simple Genetic Inheritance

The gene, which is a structural component of the chromosome, is the tiniest unit of inheritance. When a disorder is caused by genes located at a single location on a pair of chromosomes, it is classified as being merely inherited.

Simple Recessive: Recessive disorders arise when the expression of a particular trait necessitates the presence of two copies of a gene (homozygous dd). The symbol “recessive” is represented by minuscule letters. Given their recessive nature, the gene is concealed within the heterozygote form Dd, potentially resulting in a low prevalence within the population. The complete elimination of a recessive gene from a herd is a challenging task. Mating between related individuals raises the probability of discovering recessive disorders.
Simple Dominant: When the manifestation of the defect requires only one copy of the gene (D), it is classified as dominant. Capital letters are used to represent dominant alleles. Naturally, dominant traits are typically associated with mild abnormalities, as animals harbouring severe defects are typically eliminated by natural selection from consideration (DD; heterozygous; one copy of each gene; homozygous; two copies of the same gene).
Sex-associated recessive: Due to the limited number of active genes on the Y chromosome, sex-linked genes are exclusive to that chromosome. Although these genes also tend to be recessive, the occurrence of the disorder is more prevalent in males due to the presence of X and Y chromosomes, as opposed to females who possess only two X chromosomes. Female progeny can only inherit two recessive alleles (one from each parent) and exhibit a sex-linked recessive trait if their mothers are carriers.
Sexual limitation (dominant or recessive): A sex-limited malady is characterised by its occurrence exclusively in one sex due to its association with sexual differences. For instance, scrotal hernias are exclusively observed in males.

Multigenic inheritance:

Disorders governed by genes located at two or more positions on the chromosomes are multigenic. Heritability (h²) is typically estimated for these traits, providing an approximation of the degree of genetic control that the trait is subject to. Heritability estimates, which indicate what proportion of all variations in a trait can be attributed to genetic factors, vary between 0 and 1.00.

Risk of genetic liability:

Disorders that possess a genetic predisposition or propensity are those that are hereditary in nature but do not manifest until a particular environmental stimulus or assault transpires. The heritability of liability may be high, but the occurrence of the defect is minimal unless the environment is unfavourable. As an illustration, a creature that possesses an inherited propensity for splay legs may remain asymptomatic unless exposed to slippery floors or experiences a nutritional deficiency.

Experimental evidence:

Sadly, observation provides the majority of the evidence regarding genetic defects in pigs. The mode of inheritance for genetic abnormalities has been the subject of inconsistent scientific consensus in previous evaluations. Limited deliberate investigations have been initiated to examine the theories pertaining to inheritance. Hence, the remarks about the majority of the subsequent anomalies are merely approximations at best.

C. Important Genetic Abnormalities

Porcine stress syndrome:

Porcine stress syndrome (PSS) is a condition characterised by a gradual increase in body temperature, muscle rigidity, and metabolic acidosis, leading to the death of pigs with excessive muscle mass. PSS is a recessive autosomal inherited disorder, and piglets with homozygous or heterozygous positive piglets may be chosen as carriers or reactors, increasing the frequency of the associated gene. To reduce the occurrence of PSE and PSS, all animals carrying PSS, including their parents and littermates, should be removed from the reproductive herd. PSS is caused by a defect in the Ca release channel gate, resulting in protracted acidosis and fatal collapse. A DNA test can be used to identify the presence or absence of the mutated gene, and animals can be classified as normal (NN), heterozygote carriers (Nn), or stress reactors (nn).

Carriers of the dominant gene produce loin with decreased pH, paler colour, diminished protein extractability, water holding capacity, and increased heating loss. Positive characteristics of carriers include increased acidity, enhanced taste and odour, and reduced shear force value. This condition arises from the inheritance of a single gene containing two alleles in a dominant recessive fashion. Muscle glycogen stores are increased due to the dominant allele (RN), which increases lactate production and decreases ultimate pH. The three genotypes can be classified based on their glycolytic potential estimates, but the molecular basis remains unidentified.

Scrotal hernia:

Males are thought to have this sex-specific condition due to a deficiency in the musculature encircling the inguinal canal, which allows the intestines to descend into the scrotum. It is considerably more prevalent on the left side.

In general, extreme caution during castration will avert substantial economic loss. Although the mode of inheritance has been proposed to involve a minimum of two pairs of chromosomes, maternal and environmental factors are certain to be at play. In populations characterised by a high incidence rate, the heritability of scrotal hernia liability seems to surpass 0.5. When the occurrence rate is substantial within a herd and the responses to the enquiries presented earlier suggest a genetic origin, the incidence can be diminished by removing the affected individuals, as well as their parents and littermates from the breeding herd.

Scrotal hernia in pigs

Umbilical hernia:

The condition in which the abdominal wall becomes perforated due to diminished abdominal support muscles is known as an umbilical hernia, “belly rupture,” or “belly bust”. Although some affected individuals may perish during development as a result of intestinal obstruction, the majority achieve market weight without any discernible negative consequences. Surgical correction is infrequently advised. Despite the possibility of genetic factors, ambient influences, such as genital infections, are considerably more probable. The genetic susceptibility of this defect might be exacerbated by unfavourable environmental circumstances, such as overcrowding for heat preservation during chilly seasons. Due to the unknown genetic causes of this condition, it is not advisable to cull related individuals. Surgically corrected animals must never be utilised for reproductive purposes.

Large umbilical hernia in a pig

Atresia ani:

This particular condition is distinguished by the absence of a rectal opening in a newborn pig. Boar piglets that do not have a surgical incision created to allow for defecation perish within a few days. It is not uncommon for females lacking an anal opening to defecate via the vulva (a passageway connecting the rectum and vagina) while maintaining normal growth. The condition undoubtedly has a genetic underpinning, but it cannot be attributed to a single gene in particular. If the aforementioned enquiries reveal a genetic aetiology and the incidence rate is substantial, it is possible to mitigate the condition by removing from the breeding herd all afflicted individuals, their parents, and their littermates.

Atresia ani in a female pig

Cryptorchidism:

Male pigs, known as cryptorchids or ridglings, have one or both testicles retained within the body cavity. Sterile animals are those that retain both testicles. It appears conceivable for at least two gene pairs to express sex-limited inheritance. It is recommended that affected individuals’ parents and littermates be excluded from the breeding herd.

Cryptorchid (one testicle retained) in the male pig

Hermaphrodites:

Hermaphrodites are found in the Yorkshires and Landrace in the United States and between 0.1% and 0.5% in the Large White and Landrace strains of Europe. Sex chromatin studies show that most hermaphrodites are genetically females, despite carrying male sex organ components. USDA research suggests that female progeny of identified carriers segregate in a 3:1 unaffected-to-affected ratio, with sex-limited recessive inheritance being the underlying mechanism. Other hypotheses include altered chromosome structure, such as translocation of a segment of the Y chromosome to the X chromosome or elimination of the depressing effect of maleness through a mutation in the X chromosome. Simple genetic factors typically regulate hermaphrodites, and culling affected individuals, their parents, and littermates can help reduce the incidence. Hermaphrodite females can procreate in large litters due to uterine congestion, similar to Freemartin syndrome in cattle.

Hermaphrodite pig with large clitoris

Nipple abnormalities:

The most significant underlying abnormality is inverted nipples. This condition is distinguished by the inability of the nipples to emerge from the surface of the udder. By drawing the teat canal inward and creating a small crater, the regular flow of milk is obstructed. The degree of involvement of the number of gene pairs in this anomaly remains undetermined. The heritability is projected to be around twenty percent. It is prudent to exercise caution when assessing outlines, as the presence of the nipple tip does not cause nipples encompassed by a rim of loose skin to appear inverted. Near the sheath of boars, nipples are frequently erroneously categorised as inverted. Pruning parents and littermates is not advised due to the genetic ambiguity surrounding this particular trait. It is not advisable to incorporate organisms that possess a significant proportion of inverted nipples into the reproductive herd.

Blind nipples are those in which neither the nipple nor the canal are visible. These are typically attributed to physical harm, specifically irritation and scabbing brought on by abrasive flooring surfaces. Therefore, the aetiology of blind nipples is not attributed to genetic factors.

Inverted nipples in nursing pig

Tremors:

Porcine tremors, also known as shivering, shakers, myoclonia congenita, or jumpy pig disease, are congenital and typically manifest within a few hours of birth. These symptoms are characterised by the rhythmic quivering of the neck and legs, with minor tremors allowing movement and nursing, while severe cases become immobile and susceptible to malnutrition, chilling, and sow overfeeding. As survivors age, they experience symptoms of lesser intensity.

Porcine circovirus has been isolated from pigs exhibiting congenital tremors and may contribute to developing this condition. There are five distinct categories of tremors in pigs with morphological lesions, with antiviruses being the causative agents of types A and AII, while high-frequency types AIII, AIV, and others are subject to genetic regulation.

Transplacental infection with specific genotypes of the porcine cholera virus results in Type AI, which reduces the extent of both the cerebellum and spinal cord. Type AII is transmitted via the placenta and is not caused by pig cholera. Type All is typically associated with an abrupt increase in vibration frequency. AII type is an inherited trait, exclusively Swedish landrace, inherited in a sex-to-linked recessive manner. Type AIV is exclusive to the British Saddleback breed and is classified as a simple autosomal recessive trait.

Leg defects:

Muscular lethargy and a severe tremor of the legs are distinctive features of high-frequency tremors, which manifest during walking and standing but not while immobile in a supine position. As age progresses, the severity of the tremor and muscular frailty escalates, leading to increased instability when upright. The inheritance pattern of high-frequency symptoms is autosomal dominant. In cases where the prevalence of symptoms is significant and the responses to the inquiries presented earlier suggest the involvement of type AI (or type AIV), the incidence can be diminished by eliminating afflicted individuals, their parents, and their littermates.

Leg defects in piglets

D. Infantile Diarrhoea

Escherichia coli bacterial strains frequently bring on piglet neonatal diarrhoea. Different genotypes of Escherichia coli possess distinct cell-surface antigens that, when coupled with glycoprotein receptors located on the intestinal wall of the piglet, facilitate bacterial adhesion to the intestines. The bacteria proliferate upon attachment, emitting enterotoxins that result in diarrhoea, which can cause significant morbidity and mortality. The intestinal receptor for the K88 strain of Escherichia coli is absent in specific piglets. As a result, these piglets possess resistance to K88 bacteria and K88 strain-induced diarrhoea. The absence of the K88 receptor is an autosomal recessive trait with a singular locus. Additionally, it appears probable that a single gene will encode resistance to Escherichia coli strains K99 and F4.

E. Leg Impairments

Numerous leg abnormalities have been documented in pigs. The subsequent is one of the most frequently encountered congenital anomalies.

The splay leg:

Splayed legs, also known as leg disorders, are the most common and often affect the hind legs first. Histological examinations often show incomplete development of muscle filaments in the front and back extremities. Factors such as genetic susceptibility to muscle paralysis, viral infection, nutritional deficiency, and sliding surfaces may contribute to the development of this defect. The heritability of liability may exceed 0.40 in certain types. If a significant incidence is found, a genetic cause may be implicated, which can be reduced by eliminating affected individuals, their parents, and littermates.

Minor inner digits:

The genetic basis for this condition is postulated; however, the specific mechanism by which it is inherited remains undisclosed. Typically, the duration of service in the herd is diminished in animals that exhibit this defect. It is only advisable to cull individuals who have been affected.

Lying piglets:

While this fatal anomaly predominantly impacts the forelegs, rare instances have reported involvement of the hind legs as well. The legs are rigid and bowed back at right angles. Although this disorder is inherited recessively, it can also be induced by non-genetic factors, such as pregnant sows ingesting tobacco or Jimson marijuana. A genetic cause may be inferred from queries presented in the previous section; in such cases, culling the parents and littermates of the affected individuals can help reduce the incidence.

F. Polydactyly

Dewclaws and extra digits are common genetic disorders in hogs but are economically insignificant. Syndactyly, also known as mule foot, is a rare condition transmitted through a single dominant gene. It has almost disappeared from the US pig population. Elevated forelegs, caused by connective tissue replacing muscle, are oedematous and bulky in affected piglets. Although a recessive mode of inheritance is hypothesised, there is limited evidence. A genetic cause can be inferred from the responses to previous questions, and culling affected piglets, their parents, and littermates can help reduce incidence.

G. Other Disorders

The Table below summarises several other anatomical defects of pigs. Those listed are of lower frequency, of less economic importance, or less clearly understood than those conditions described in the text.

Other disorders in pigs.

Disorder	Description	Probable cause
Blood warts (melanotic tumours)	Moles or skin tumours. Increase in size with age. Tumours are heavily pigmented and contain hair. Injury causes depigmentation. Common in Durocs and Hampshire’s.	Inheritance is unknown, but multigenic inheritance has been postulated.
Brain hernia	The skull fails to close, and the brain protrudes. Generally lethal.	Simple recessive inheritance is suggested.
Cleft palate	The palate does not close. Harelip results. Generally lethal.	Recessive lethal has been theorised but may result from multigenic genetic liability influenced by an environmental result.
Gastric ulcers	Erosion of the epithelial lining of the stomach. Generally, in the oesophageal region.	Heritability estimates ranging from low to high have been reported. Pelleted and finely ground diets, high unsaturated fats and low selenium in the diet, copper toxicity, and psychosomatic factors have been found to cause that problem.
Haemophilia (bleeders)	Slow clotting time. Death results from slight wounds or navel cord haemorrhage.	Known to be caused by mycotoxins in feed or vitamin K deficiency. Once confirmed case of simple recessive inheritance.
Humpback	Crooked spine behind the shoulder.	It is likely to have a genetic cause, but inheritance is unknown.
Hydrocephalus	Fluid on the brain. Brain cavity much enlarged.	A lethal gene is inherited as a simple recessive.
Lymphosarcoma (Leukaemia, lymphoma)	Malignant tumours of the lymph nodes with increased lymphocyte count. Stunted growth and death before 15 months of age.	Convincing evidence of an autosomal recessive.
Motor neuron disease	Distinctive locomotor disorder of nursery pigs, characterised by the inability to coordinate muscle movements and slight paralysis.	Strong suggestion of autosomal dominant inheritance.
Oedema (myxoedema, dropsy, hydrops)	Abnormal accumulation of fluid in tissue and body cavities is suggested. Possibly associated with a thyroid defect.	Autosomal recessive disorder.
Pseudo-vitamin D deficiency (rickets)	Indistinguishable from non-genetic lack of vitamin D resulting from calcium deficiency or insufficient exposure to sunlight. The most noticeable effect is the bowing of the limbs.	Inherited as an autosomal recessive.
Rectal prolapse	Protrusion of the terminal part of the rectum and anus.	Many environmental influences, including coughing, piling, feed constituents, antibiotics, and diarrhoea, have been implicated, though genetic liability may exist.
Persistent frenulum	A close attachment of the prepuce to the body by a mucous membrane results in inadequate protrusion of the penis and inability to breed.	Inheritance unknown.
Screw tail (kinky tail)	Flexed, crooked or screw tail caused by fusion of caudal vertebrae.	Multigenic recessive inheritance has been postulated.
Swirls hair (hair whorls)	Forms a cowlick or swirl on the neck or back.	At least two pairs of recessive genes.
Wattles fleshy (tassels, bells)	Cartilaginous appendages are covered with normal skin and suspended from the jaw.	Single-focus autosomal recessive inheritance.