A. Nutritional Deficiencies
Piglet iron deficiency is a prevalent nutritional deficiency observed in pig farms. An essential responsibility of the livestock producer on the farm is to ascertain the correlation between the feed’s quality, content, and ingestion, and the pig’s age and/or productive cycle. In this regard, management has a significant impact on disease levels in the herd and the extent to which the pig realises its biological potential.
Example of a nutritional deficiency in pig in a farm health plan.
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NUTRITIONAL DEFICIENCIES |
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Problem(s) seen: Iron deficiency |
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Signs of nutritional anaemia in suckling pigs include pale mucous membranes, skin oedema about the neck and shoulders, listlessness, and spastic breathing (thumps). |
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Treatment and Prevention: |
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Administration of supplemental iron (100 to 200 mg) with water-soluble iron given by mouth or parenteral injection of iron dextran. |
B. Under- and Over-feeding
Feeding of pigs
There are as many problem herds as the result of overfeeding as there are of underfeeding. The problem of overfeeding is becoming increasingly more important as the intensified type of agriculture becomes more prevalent. Pregnant sows should be kept in good condition but not fat. Often sows are fed too much corn or allowed to be in the corn fields where they find too much grain. The amount fed to the sows should be regulated according to their condition. Oats, alfalfa meal, and pasture are desirable feeds which will prevent sows from becoming too fat. If the sows become too fat, increase the amount of oats or alfalfa meal. If they become too thin, increase the amount of corn.
Ration for sows during the gestation period:
An adequately nourished expectant sow will likely encounter minimal challenges throughout the stages of parturition and lactation. A comprehensive regimen for self-feeding sows during gestation consists of the following:
- Ground corn 272.16 kg
- Ground oats 272.16 kg
- Alfalfa Meal 226.8 kg
- Sow Supplement 61.7 kg
C. Nutritional Diseases
Observational diagnosis of nutritional deficiencies is challenging. Clinical manifestations are frequently the consequence of a confluence of malnutrition, infectious diseases (parasitism included), and poor management. The symptoms of nutritional deficiencies are generally non-specific, such as diminished growth, lack of appetite, and malnutrition. Insanity can result from a deficiency in a single nutrient; subsequent deprivation can lead to the development of multiple deficiencies. Additionally, a nutritional deficiency may manifest itself in the absence of obvious symptoms. Diagnosis can be challenging when the deficiency is minimal or ambiguous, as observed in the field.
It is not always possible to make a definitive diagnosis of a deficiency based on the response to nutritional therapy; this is especially true for chronic deficiencies that can cause irreversible damage. A nutritional deficiency should only be affirmatively diagnosed after the meticulous examination of the animals’ dietary, disease, and management history, as well as the observation of several of the anticipated clinical indications.
Protein deficiency:
Pigs in the growth and concluding stages develop protein deficiency, which can be attributed to inadequate feed ingestion or a lack of one or more essential amino acids. This condition manifests as diminished gains, suboptimal feed conversion, and fatter carcasses. Milk production is diminished, sows experience weight loss in excess, and they may exhibit a delayed return to oestrus or fail to demonstrate postweaning oestrus. All essential amino acids must be released during metabolism at rates proportional to requirements for protein to be utilised optimally. As a result, protein supplements ought to be freely available with grain at all times or blended with it rather than being hand-fed at irregular intervals. There is currently an absence of empirical evidence to substantiate the hypothesis regarding “protein poisoning” in pigs. It was discovered that diets containing 35 to 50% protein were laxative and less efficient in terms of utilisation, but no deleterious effects were observed.
Deficiency in fat:
Specific polyunsaturated fatty acids with lengthy chain lengths are vital for livestock. Linoleic acid is a dietary essential and is likely utilised in the synthesis of longer-chain fatty acids, which are also essential. In developing piglets, a deficiency in linoleic acid results in hair loss, callous dermatitis, necrosis of the skin on the neck and shoulders, and an untidy appearance. In general, standard porcine diets consist of sufficient fat derived from natural sources, which provides ample quantities of vital fatty acids.
Mineral deficiency:
Phosphorus or calcium deficiency causes osteocalcin in mature piglets and rickets in developing pigs. In juvenile piglets, symptoms include lameness, deformity, and bending of long bones; in elderly pigs, fractures and posterior paralysis (caused by lumbar fractures) are observed. Insufficient dietary calcium or phosphorus can render particularly susceptible to posterior paralysis sows that produce large litters and copious amounts of milk towards the end of lactation or after weaning. Although vitamin D deficiency can also lead to these symptoms, phosphorus deficiency is the most frequent cause.
Poor growth and inefficiency characterise pigs fed low-sodium (NaCl) diets, primarily due to a significant reduction in feed ingestion. While not exclusively associated with sodium deficiency, adverse effects on the hair and epidermis may also manifest. Salt-deficient pigs endeavouring to consume the excrement of other pigs have been documented.
Diets deficient in iodine cause piglets to be born hairless, frail, or stillborn. Notwithstanding initial weakness, neonatal piglets with borderline deficiency exhibit thyroid enlargement and histologic abnormalities. Certain feed ingredients, such as soybeans and soybean meal, contain goitrogens that, in the absence of iodine, may induce peripheral goitre. At the recommended levels, iodised salt prevents this deficiency.
Iron and copper deficiency inhibit the formation of Hgb, resulting in the characteristic nutritional anaemia. Low Hgb and RBC counts, pallid mucous membranes, an enlarged heart, cutaneous oedema around the neck and shoulders, lethargy, and erratic respiration are all indicators of nutritional anaemia in suckling piglets. Iron deficiency is more prevalent than copper deficiency and is particularly prevalent in lactating piglets that do not initially receive oral iron or an iron injection.
Growing pigs fed diets high in phytic acid (or phytate, the principal form of phosphorus found in cereal grains and oilseed meals) and over the recommended calcium intake develop parakeratosis due to a zinc deficiency. The precise mechanism by which zinc inhibits parakeratosis remains unknown.
Vitamin E and selenium deficiency can result in the unexpected demise of young, swiftly developing piglets. Moreover, lactating piglets deficient in selenium and vitamin E are more vulnerable to iron toxicosis caused by iron injections.
Vitamin deficiency:
Vitamin deficiencies are less prevalent than they were in the past due to the widespread availability of vitamin premixes for farm-mixed feeds and the fortification of the majority of commercial diets with vitamins. Eye dysfunction and damage to the epithelial tissues of the respiratory, reproductive, nervous, urinary, and digestive systems are symptoms of vitamin A deficiency. Sows experience reproductive impairment, which can result in the birth of piglets that are blind, eyeless, frail, or malformed. It has been reported that herniation of the spinal cord in foetal piglets is the only indication that expectant sows are deficient in vitamin A. Growing piglets that are deficient in vitamin A develop respiratory disorders and night blindness, in addition to incoordination. A deficiency in vitamin A is uncommon due to the liver’s capacity to store this vitamin.
Vitamin D deficiency is characterised by the presence of rickets, rigidity, flexed and weakened bones, and posterior paralysis. These symptoms are virtually identical to those associated with a deficiency in calcium or phosphorus.
A deficiency in vitamin E may lead to compromised immune function and impaired reproduction. Selenium deficiency exhibits numerous symptoms that are comparable to those of vitamin E deficiency.
Vitamin K deficiency induces protracted blood coagulation and increases the risk of death from haemorrhages in pigs. Specific constituents present in mouldy feed have the potential to impede the synthesis of vitamin K. Furthermore, the presence of an inordinate amount of dietary calcium disrupts the activity of vitamin K, resulting in the manifestation of these symptoms.
Reproduction is impaired in piglets deficient in riboflavin; postpubescent gilts fail to cycle but exhibit no other clinical symptoms. Sows that are deficient exhibit anorexia and give birth to deceased piglets 4–16 days early. Stillborn piglets typically have sparse hair, are frequently partially resorbed, and may exhibit elongated forelegs. Piglets that are raised on diets deficient in riboflavin experience sluggish weight gain, a lack of appetite, a coarse coat, exudate on the skin, and potentially cataract formation.
Niacin-deficient pigs develop diarrhoea, weight loss, harsh skin and texture, inflammatory lesions of the digestive tract, and dermatitis of the ears. Bacterial infection or a niacin deficiency may contribute to intestinal disorders. Niacin therapy is readily effective for deficient pigs, and while it does not provide a cure for infectious enteritis, sufficient dietary niacin likely sustains the pig’s resistance to bacterial invasion.
On diets deficient in pantothenic acid, growing piglets and expectant sows develop a characteristic “goose-stepping” gait, ataxia, and non-infectious bleeding diarrhoea. Anaemia develops as the deficiency progresses to a severe degree.
Choline deficiency is characterised by a lack of coordination and an abnormal shoulder conformation in pigs. They typically exhibit obese livers and kidney injury upon necropsy. Choline-deficient sows may deliver spraddle-legged piglets and have litters of smaller size.
A biotin deficiency is characterised by various symptoms such as excessive hair loss, dermatitis and skin ulcerations, exudates around the eyes, inflammation of the mucous membranes of the mouth, transverse splitting of the hooves, and footpads that fracture or haemorrhage.
Vitamin B-deficient synthetic diets induce hyperirritability, voice failure, pain, and incoordination in the hindquarters of neonatal piglets. Upon histologic examination of the bone marrow, a hematopoietic system impairment is evident. During necropsy, fatty livers are also detected.
D. Treatment of Malnutrition or Feeding Programme
Malnutrition in pigs
Both the daily quantity ingested and the feed quality impact the performance of weanling, growing, and finishing pigs, gestating sows, lactating sows, and their nursing piglets. The overall feeding management process must be aware of the quantity of grain that animals ingest. Feeder design, crowding, energy density of the diet, feed quality (such as the absence of moulds), and environmental temperature, in addition to a multitude of other management factors, typically regulate the amount of feed that weanling, growing, and finishing pigs are permitted to consume ad lib.
Growing-finishing pigs:
Different weight classes of growing-finishing piglets were analysed for their daily feed intakes on a diet containing 3 300 kcal of ME/kg. The following intake levels are indicative of the mean for barrows and gilts. A gilt’s feed intake will be marginally lower than that of a barrow carrying 50 to 135 kg. Automatic water sprayers used to cool piglets and prevent overcrowding during sweltering weather ameliorate reduced feed intake. Prescribed in-feed medication or estimation of total feed requirements may be facilitated by these intake levels.
Gestating gilts and sows:
The National Research Council (NRC) recommends a feeding level of 2.1 to 2.2 kg/day for gilts and sows during the initial 90 days of gestation and 2.5 to 2.6 kg/day from the final 25 days until farrowing on a corn-soybean meal diet (3 300 kcal ME/kg) to meet maintenance energy requirements, facilitate lean and fat tissue accretion, and support developing tissues. Mature sows require only the energy necessary for maintenance and a slight increase in body mass. However, incorporating cereals, alfalfa meal, or other energy diluents into gestation diets may require increased nutrition. Being overweight at the end of gestation can lead to adverse outcomes such as smaller litter sizes, increased prevalence of dystocia and porcine overlay, and increased susceptibility to postpartum deescalate syndrome. Poor body condition can also result in shoulder lesions, lower birth weights, slender sows at weaning, and delayed return to post-weaning oestrous. Additionally, poor body condition during breeding may decrease subsequent farrowing litter size.
Lactating gilts and sows:
According to the NRC, to meet their daily energy needs, lactating gilts and sows rearing 11 to 11.5 piglets that gain 240 g/day over 21 days must consume 5.9 to 6.6 kg of feed (3 300 kcal of ME/kg). Energy and feed requirements are contingent upon the number of piglets being cared for, the weight gain of the pigs (both of which impact milk production), and the sow’s weight reduction. During lactation, sows should be provided with ad libitum high-energy diets or be manually fed their daily caloric intake three times per day. Drip-coolers and appropriate temperature modulation in the farrowing chamber serve to mitigate the adverse effects of excessive heat on feed intake.
Low feed consumption during lactation can result in excessive weight loss in sows. Should this pose a challenge, it is advisable to contemplate supplementing the lactation feed with an additional 3 to 6% fat or utilising top dressing. If difficulties persist, increased energy levels during the last three to six weeks of pregnancy could be beneficial.
Prolific sows suckling large litters should be provided with diets rich in protein and amino acids to optimise milk production and mitigate the risk of excessive weight loss. Such sows may necessitate diets comprising crude protein at a minimum of 0.9% lysine and 16 to 18%. When energy intake is adequate, lactating sows will experience minimal or no weight loss when on high-protein lactation diets.
E. Major Feed Ingredients
Cereals are the major ingredients in pig feed
A fundamental tenet of pig production economics is the utilisation of cost-effective cereal grains for feed and supplementation of deficiencies with high-quality protein sources, minerals, and vitamins. Complete manufactured supplements containing dependable mineral and vitamin premixes are commercially available. Although fortified corn-soybean meal diets are widely utilised in pig operations, alternative sources of protein and cereals may also be incorporated.
- Corn (maize) is by far the most commonly used grain for pig fodder. It is extremely palatable, energy-dense and crude protein content is relatively low. In addition to vitamins and minerals, corn is deficient in lysine, tryptophan, threonine, and several other essential amino acids.
- Sorghum grain is the primary source of sustenance for boars in South Africa. The protein content exhibits variability contingent upon environmental factors including but not limited to variety, irrigation or arid land cultivation, fertiliser application, and quantity. Generally speaking, grain sorghum can be used as an equal-weight substitute for maise; however, due to its marginally lower ME value compared to corn, one can anticipate a diminished feed conversion.
- Wheat is comparable in energy content to corn, but it is 2 to 3% higher in protein and 0.05 to 0.1% more lysine. Wheat may be used in place of corn on a lysine basis or in an equivalent weight ratio; however, it should not be substituted on a crude protein basis, as doing so would lead to a lysine deficiency. Wheat can be the sole cereal component of a pig’s diet.
- Barley has 85 to 90% of the nutritional value of maise is contained in barley, even though it typically has 2 to 3% more protein. Pigs should not be fed scabby barley.
- Due to their comparatively low caloric content, oats ought not to constitute more than 20 to 25% of the cereal grain intake. It is generally anticipated that the rate and efficacy of gain will decrease when grains are incorporated into the diet. Groats made from rolled oats are occasionally incorporated into starter diets due to their exceptional palatability.
- Rolling or grinding cereal grains will maximise their nutritional value. It is recommended to reduce corn and cereal sorghum to a particle size of medium-fine (550 to 600 microns). To avoid plastering, wheat should be pulverised more coarsely (650 to 700 microns). Although feed conversion is enhanced by fine grinding, an excessive reduction in particle size may increase the risk of gastric ulceration. There is a possibility that pelleting diets could lead to a marginal enhancement in both gain and feed efficiency. High-fibre pelleted diets, such as those formulated with barley, generally provide the most significant advantage. From mycotoxins, cereal grains should be as free as feasible. Depending on the concentration in the feed, aflatoxins, vomitoxin, zearalenone, feminising, and other mycotoxins can diminish the performance of animals and, in the case of reproducing animals, can cause reproductive issues.
- Pigs in South Africa are provided with over 90% of their supplemental protein from soybean It has an exceptional amino acid profile that complements the amino acid pattern found in cereal grains and is extremely palatable. However, before feeding the pig, ground, whole soybeans must be heated (via roasting or extrusion) to destroy trypsin inhibitors and other heat-sensitive antinutritional components.
- Canola meal is an exceptional source of protein as well. Due to the lower lysine content of their proteins, low-gossypol cottonseed meal (100 ppm free gossypol), peanut meal, sunflower meal, and other oilseed-based meals may be utilised as supplementary protein sources in pig feed; however, they should not be used exclusively. Fifty percent of the protein required for porcine diets may be derived from animal sources, including meat meals, meat and bone meal, or fish meal.
F. Feeding Management of Sows and Litters
Therefore, it should be provided with gestation rations that are sufficient in all nutrients to produce robust, healthy piglets. It is ideal for farrowing sows that have achieved a healthy body condition – without becoming excessively emaciated or obese. In general, thinner sows produce smaller piglets with inferior survival prospects compared to their larger, more robust counterparts. The show should be promptly reintroduced to a complete diet following farrowing. Constipation in sows is typically not an issue when the sow maintains a healthy diet. For farrowing experiencing constipation, 5 to 10% wheat cereal or dried beetroot purée may be incorporated into the diet. Alternatively, 0.75 to 1% chemical laxatives such as potassium chloride or magnesium sulphate may be utilised.
It is necessary to examine newly farrowed piglets to ensure that each one has weaned. Oxytocin may be administered to accelerate milk production if necessary. Weak piglets may benefit from artificial milk if the sow is sluggish to produce milk; however, success is contingent on proper management and sanitation. To prevent nutritional anaemia, an iron injection should be administered before the third day of life, or alternative methods as previously discussed. After receiving colostrum, pigs from sizable litters may be transferred to sows with smaller litters; nevertheless, this transfer must occur within the initial twenty-four hours following delivery. If piglets are to be weaned after three weeks of age, a palatable initial diet for pigs should be provided between two and three weeks of age.
Feeding management of weanling pigs:
Early weaning of pigs (3 to 4 weeks) followed by 1 to 2 weeks on a sophisticated initial diet optimises their performance. In general, the initial diet comprises desiccated blood products, dried whey and/or lactose, and an abundance of lysine. Certain producers employ medicated early weaning or segregated early weaning programmes to ensure that their piglets are healthier. Weaning occurs between 10 and 16 days of age and necessitates meticulous nutritional supervision. In addition to elevated quantities of lysine, these diets should also be rich in lactose (in the form of sucrose or dried whey) and desiccated animal plasma ranging from 3 to 7%. Eventually, a transition to initial diets containing less expensive corn-soybean meal should occur.
A full-feeding programme delivers the most optimal nutrition for growing-finishing piglets. Limit-feeding may enhance the carcass quality of finishing piglets while decreasing the rate and efficiency of attainment. Self-feeders must be designed and adjusted appropriately to prevent feed waste and growth restriction.
Growth stimulants:
Antibiotics and other chemotherapeutic agents have been widely used in pig diets for several years to improve health, reduce mortality, and stimulate growth and feed efficiency. The most effective response is observed in juvenile piglets, but as they age and gain weight, the response diminishes. Dosing and withdrawal criteria must adhere to manufacturer guidelines and legal restrictions.
Antibiotics approved for use as feed additives include Bacitracin methylene salicylate, Bacitracin zinc, bambermycin’s, chlortetracycline, lincomycin, neomycin, oxytetracycline, penicillin, tiamulin, tylosis, and virginiamycin. Chemotherapeutic agents like Sulfathiazole, carbadox, roxarsone, and sulfamethazine are also approved when used in conjunction with specific others. Apramycin is permitted for use as a water medication, and pharmaceutical concentrations of copper are effective growth stimulants for juvenile piglets.
Live cultures of probiotics, such as Saccharomyces cerevisiae, Streptococcus acidophilus, and Lactobacillus acidophilus, have been assessed as potential alternatives to antibiotics, but controlled investigations have failed to demonstrate consistent and beneficial outcomes. Specific “repartitioning agents” like Ractopamine and porcine somatotropin are highly effective at increasing growth rate, feed conversion, and carcass leanness in finishing pigs.
Vaccinations in Pig Production
Vaccination programme in pig production
A significant role is played by vaccination in averting livestock maladies and fatalities. This is complementary to both internal and external parasite management. When exposed to microorganisms, animals develop immunity to them. This process takes place in livestock and wildlife through natural immunisation; however, it is not without drawbacks, as an animal may contract an illness, deteriorate significantly, sustain irreparable harm, or perish.
Consequently, vaccines have been created to prevent these dangers.
Vaccine microorganisms are either rendered ineffective or rendered inactive, thereby eliminating their capacity to induce disease. Following vaccine administration, the body generates an immune response via antibody stimulation or the production of cellular immune system components.
Farmers should adhere to a meticulously planned vaccination regimen for their livestock. Each pig farmer should collaborate with a veterinarian to develop a farm-specific immunisation programme for his or her animals, given that diseases and agricultural practices vary from region to region.
Basic vaccination schedule for commercial piggeries.
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Animal |
Vaccination |
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Gilts |
At selection vaccinate against Parvo, Erysipelas and E. coli. 1 month later or when the service period starts, repeat Parvo and Erysipelas vaccines. Give the second E. coli vaccine 3 – 4 weeks before farrowing. |
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Sows |
At every weaning, vaccinate against Parvo and Erysipelas. 3 weeks before every farrowing, vaccinate against E. coli. If this is impractical in your situation, vaccinate all sows every 6 months with Parvo, Erysipelas and E. coli. |
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Boars |
Vaccinate boars against Erysipelas and Parvo twice a year. |
It is recommended that the farmer consult with a veterinarian regarding mandatory vaccinations, recommended vaccinations, and non-mandatory vaccinations which should be administered only occasionally.
The following is a standard vaccination schedule for producers purchasing or producing show hogs. While it is true that any vaccination programme should be customised to the unique health history and requirements of each farm, this protocol may serve as a foundation for a farm-specific initiative. Advised vaccines are denoted in bold, while farm-specific options are italicised. In general, gullets necessitate two vaccinations to acquire optimal immunity, whereas sows that have already been vaccinated during their prior gestation or lactation period only need one vaccination to reinforce their immunity.
Vaccinate sows that have not been immunised since their most recent lactation in the same manner as gilts without a prior vaccination record.
In light of the influence outbreaks that occurred at certain county fairs in 2012, the administration of influenza vaccinations to pigs has been upgraded from an elective procedure to a mandatory one according to our protocol. We maintain our recommendation regarding the vaccination of the piglets against Circovirus, Mycoplasma, and Erysipelas. It is mandatory for all breeders who farrow show pigs to vaccinate the piglets against the following four maladies before selling them. This will ensure that these piglets exit the farm with a robust immune system. It is advisable to administer the Reseizure or ER Bac combination for Mycoplasma and Erysipelas, while individual vaccinations for
Administration of veterinary medications:
Vaccinations that are specific to various classifications of pig
Piglets in masse: Inject Reseizure intramuscularly into the muscle behind the ear of the piglet at one week of age. Three weeks later, administer Reseizure along with Foster PCV Meta Stim.
Each injection should be administered to a distinct side of the neck. When injecting piglets, always use disinfected syringes and needles, and employ a short, finer gauge needle. Because disinfectants can compromise the efficacy of vaccines, previously used injection apparatus should be sterilised with scalding water rather than disinfectants.
Gilts (young sows being mated for the first time): Farrow Sure GOLD B should be injected into the muscle behind the ear of the animal five weeks before breeding or mating, and again two weeks before mating. Inject the animal with Litter Guard LT-C five weeks before delivery, and once more administer this vaccine two weeks before farrowing. Bear in mind that the average gestation period for piglets is three months, three weeks, and three days; however, it is not unusual for the period to span from 111 to 120 days.
Maintaining accurate records of piglet birth and mating times, deworming and vaccination dates, as well as dates of farrowing and mating, is crucial for ensuring the viability of a vaccination programme. It is advisable to document these dates on a calendar and display the records in a conspicuous location.
Sows: Inject the animal behind the ear with FarrowSureGOLD B two weeks before mating or breeding, and with LitterGuard LT-C two weeks before farrowing. Sows and gilts will require syringes and needles that are marginally longer and denser than those utilised on piglets. For further guidance, consult the farmer’s supply store.
Boars older than 10 weeks are administered Improve and a subsequent vaccination may be scheduled four to five weeks before despatch. This product facilitates improved fat marbling and consequently enhances the fat quality of the carcass. Additionally, it aids in the mitigation of carcass lesions that may result from aggressive mating behaviour.
Precautionary measures:
A volume of 2 ml per animal is administered intramuscularly (in the muscle of the neck behind the ear) for the aforementioned vaccines. Adult pigs typically necessitate the use of a lengthier needle in comparison to piglets due to the potential presence of substantial fat in the neck region that must be pierced before accessing the muscle.
Consult with an expert regarding which syringes and needles are appropriate for each category of pig. It is imperative to consistently employ sterile apparatus and wash hands thoroughly with detergent before and following the administration of vaccines or any other medication.
It is imperative to exercise the greatest possible care when vaccinating piglets that may exhibit aggressive behaviour towards their handlers. It is imperative to exercise caution and immobilise the pig before administering any type of injection. Humans are frequently inadvertently harmed by needles when piglets are agitated and leaping during injection. When being handled, certain pigs, especially elder suckling sows and boars, may exhibit exceedingly aggressive behaviour towards humans.
Aftercare:
Immediate disinfection and medical attention should be sought following a pig puncture. Other practices such as good sanitation, general piggery hygiene, facility biosecurity measures, functional housing facilities, and constant good sustenance are crucial for sustaining a functional farming operation, even though vaccines significantly reduce the likelihood of pigs contracting diseases. Vaccines are typically heat-sensitive; therefore, when transporting them, they should be secured to ice and stored in a freezer bag or package, out of direct sunlight. Expired or compromised vaccines that have been exposed to extreme temperature fluctuations may be rendered ineffective and should be avoided.