Fernando Grasso » 10.Pigs

Swine housing

Swine housing
The majority of pigs today are raised in total confinement. Good, efficient housing makes management easier and helps the farmer to successfully rear 85 % or more of all the live born piglets to market weight in the shortest possible time.

Pork production systems
Some farms still keep and mate sows, farrow the liters and raise piglets to market weight. These are called farrow to finish operations.
Other farmers engage in weaner production, maintaining breeding herds but selling all their piglets at around ten weeks of age to some other farmer. Those who keep no breeding animals but purchase all of their pigs from weaner producers are called finishing or feeder operators. The pig finishers or feeders then takes care of these purchased animals until they reach market weight.

The pork production sequence can be divided into five phases: mating, gestating, farrowing, nursery and growing-finishing.
Animals have specific needs at each of these stages, requiring appropriate husbandry and facilities to ensure that they receive proper attention and care.
The comfort zones and management requirements change substantially throughout a pig’s life.
Confinement housing is capital intensive for both buildings and equipment but provides opportunity for automation and labor reduction. Proper operation of these systems demands considerable management expertise.
Special areas must be provided for animals in various stages of the production sequence.

Intensive pig farming

Intensive pig farming
Intensive piggeries (or hog lots) are a type of factory farm specialized in the raising of domestic pigs up to slaughter weight. In this system of pig production, grower pigs are housed indoors in group-housing or straw-lined sheds, whilst pregnant sows are confined in sow stalls (gestation crates) and give birth in farrowing crates.
Pigs are kept in large stalls with large numbers of pigs per square meter. The temperature is raised which allows the pig to spend less energy on keeping its body heat at the right temperature so it gets fat quicker enabling the process to be much more efficient.
Intensive piggeries are generally large warehouse-like buildings.
Indoor pig systems allow the pigs’ conditions to be monitored, ensuring minimum fatalities and increased productivity.
Buildings are ventilated and their temperature regulated.
Most domestic pig varieties are susceptible to heat stress, and all pigs lack sweat glands and cannot cool themselves.
Pigs at different stages of growth need different environments (temperatures). If they are to produce and grow to their maximum potential, piglets need special protection against very low temperatures. Growing and reproducing pigs must be protected against high temperatures.
Pigs have a limited tolerance to high temperatures and heat stress can lead to death. Maintaining a more specific temperature within the pig-tolerance range also maximizes growth and growth to feed ratio.

Production cycle

Pig production cycle. From: UK Agricolture

Production system

Description of the pig production systems.

Swine reproduction

Swine estrous cycle
The estrus cycle length averages 21 days. Gilts come in to first estrus around 8 months of age.
The sow is polyestrous, with a period of lactational anestrus occurring until after weaning.
Estrus (heat behavior) occurs for 2-3 days, averaging 60 hours in mature sows, but is only about 48 hours long in gilts. Ovulation occurs during the last third of estrus.

Heat detection
The goal is to recognize when the sow or gilt reaches “standing heat”.
The standing reflex is stimulated by contact with a mature boar. The boar’s submaxillary salivary glands produce pheromones that are secreted into the saliva. Direct physical contact is the best way to ensure that these stimulatory chemicals are transmitted to the female. The pheromones signal to the female that a mature boar is present and initiate the standing reflex if the female is in estrus. The female may or may not also exhibit other visible signs.
Sows in estrus will often assume this rigid stance when pressure is applied on the rump (“back-pressure”) by the herdsman. This is an instinctive response that braces her to support the weight of the boar.
The classic sign of standing heat is “ear popping,” in which the female holds her ears erect with the tips nearly touching when weight is applied to her loin.
Detection of standing heat is critical because it determines when the animal should be inseminated.
Gilts should be bred 12 hours after standing heat is detected, and again 12 hours after the first insemination. Sows should be bred 18-24 hours after detection of standing heat, and again 12 hours later.

Swine reproduction

Physical signs to consider for mating

Too early

• Vulva heavily red and swollen
• Hardly any mucus on vaginal mucosa
• Negative back pressure test, only standing reflex in presence of a boar

In time

• Vulva moderately red and swollen
• Vaginal mucosa with mucus
• Positive back pressure test

Too late

• No redness or swelling of vulva
• Sticky vaginal mucosa
• Negative back pressure test, only standing reflex in presence of a boar
• 2^nd mating or AI ’s are necessary in animals with positive back pressure test 24 h after mating

Mating area

Modern units are designed to allow convenient movement of animals to appropriate quarters as their needs change during the production sequence from birth to market or during the reproductive cycle.

Mating area
Requires good lighting, footing, access to pens, and facilities for convenient movement of animal to facilitate handling of individuals and mating pairs.
For an adequate housing, the following are necessary:

• individual pens for boars;
• collective box for recently weaned sows to facilitate estrus detection;
• collective box for replacement gilts.

The boar pen
Boars are kept separately in their own pen. One boar is kept for every 15 to 20 sows. Sows are brought to the boar to be served in the boar pen. This pen should be 9 to 10 m², with the short side at least 2 m wide so that the boar can easily turn around in it. An under-roof sleep area, about a third of the size of the pen, must be covered in bedding. Straw, grass or sawdust can be used for this purpose. It is important that the temperature does not rise higher than 22 °C for long periods. On very hot days boars can be kept cool by sprinkling them with water.

Sexual behaviour

Courtship behaviour.

Artificial insemination

One of the disadvantages of AI is that it may require a higher level of management. When a boar naturally mates a sow, the semen is not subjected to severe changes in environment and is generally deposited into the female more than once during a period that spans the optimal time for fertilization. In contrast, many environmental changes are possible when semen is collected, diluted, transported and then deposited artificially.
The inseminations must be done correctly and at the optimal times. To obtain a high conception rate and litter size, estrous detection (heat checking) must be done carefully and without fail.

Detecting estrus
The goal is to recognize when the sow or gilt reaches standing heat, which is the period when she stands still and rigid when you put weight on her loin. Detection of standing heat is critical because it determines when the animal should be inseminated.
The standing reflex is stimulated by contact with a mature boar. The boar’s submaxillary salivary glands produce pheromones that are secreted into the saliva. Direct physical contact is the best way to ensure that these stimulatory chemicals are transmitted to the female. The pheromones signal to the female that a mature boar is present and initiate the standing reflex if the female is in estrus.
Swelling of the vulva is perhaps the most easily-recognized physical sign that an animal is coming into heat. In many animals the vulva swells and reddens 2 to 5 days before she is ready to breed. Some sows (and gilts) show little or no swelling.
When a female is in standing heat, the clitoris is engorged with blood, causing it to protrude outward and have a bright red color.

Farrowing area

Pregnant sows – Sows are put in the pregnant sow pen about 24 days after service and are only moved to the farrowing pen seven days before they give birth. They stay in these pens for about 85 days.
The pens can be similar to dry sow pens.

The most common area for pig parturition is the farrowing crates. These come in many designs and still allow scope for improvement.
The major challenge in designing a suitable farrowing facility is that the comfort zones for sows and newborn piglets are considerably different. Thus, supplemental heating is necessary to provide an optimum environment for the piglets.
Supplemental heating can be from electric heat lamps, radiant gas heaters, forced air or floor heating.
Inclusion of individual kennels for piglets in the farrowing crate design creates a two-environment situation where piglets can choose between different temperatures. Piglets often lie with their snouts outside and the rest of their bodies inside the curtain, taking advantage of both options.
Sows are moved in groups to farrowing sheds approximately one week prior to giving birth.
Once the sow begins to farrow, the whole litter is born within 2 to 3 hours.
Sows “farrow” litters of between 10-16 pigs, but can nurse only about 12 and excess pigs are cross fostered to sows that have less than 12 pigs.

Piglets care

It is vital that pigs nurse soon after birth since colostrum gives them some protection against infection in the first few weeks.

soon after birth:

• tie off and clip the navel cord
• clip the eight needle teeth

day 1:

• dock the tails
• identify the litters

day 3:

• castrate the males
• give iron shots

Weaning area

Newborn piglets have very limited ability to digest feed. The sow compensates for this by producing milk, a readily digested diet supplying almost all the nutritional requirements of her offspring, and offering this frequently.

Also, the immune system is immature at birth so piglets have no inherent resistance to disease and cannot generate any real protection for five or six weeks. Antibodies concentrated in sow colostrum compensate for this initial deficiency but protection is short and usually has disappeared by weaning time (i.e. in 3 to 5 weeks).
Weaning, particularly at younger ages, involves a sudden change of diet and environment, so is certainly one of the most potentially distressing stages in a piglets life.
Piglets are moved from the farrowing rooms at a weaning age which can be anywhere from 21 to 28 days depending on the producer’s system.
Pigs are grouped at weaning into pens sorted by size.

Weaning (Nursery) area

Smaller piglets do not generate sufficient body heat to warm a large area so supplementary heat is necessary at the beginning of the period in the nursery area. The nursery pigs at left have just been moved out of the farrowing facilities and placed in the nursery pen. Farmers continue to provide very warm temperatures for the pigs.
The weaned piglets will remain in nursery pens until they are between 5 to 10 weeks old. They will then be moved to a grower area. The main goal of the growing phase is to achieve high growth performance.

Growing-finishing area

Growing-finishing area

Weaned and growing pigs are usually group-housed in pens.
In well-ventilated sheds, pigs will instinctively select clean and dry areas for sleeping, resting and feeding. Pigs are very clean animals and choose to defecate in an area separate to their feeding area.
There is considerable disparity in recommendations on space requirement for growing and finishing pigs.
All housing is a compromise between maximizing performance of each pig in a pen and optimizing the financial return from investment.

Traditionally farmers produced pigs to two different weights to satisfy distinct market requirements:

• lightweight pig 90 ÷ 110 kg
• heavy pig 150 ÷ 160 kg

Carcass evaluation

Carcass grading according to lean meat percentage.

Carcass dissection

Cuts obtained from a pig carcass.