28/11/2021
Activation temperature for these systems should be set between 75º and 78º F, as opposed to between 80º and 85º degrees. While this practice may not be able to maintain a farrowing room between 75º and 78º degrees if the ambient temperature outside reaches 90º+ F, it does prolong the period over which the room temperature increases, since the cooling process begins sooner. Along with earlier activation of cooling systems, replacing heat lamps with regular "household" 100-watt incandescent bulbs will reduce the ambient temperature of the farrowing room. Furthermore, heat lamps may need to be shut off completely during periods when temperatures do not fall below 85º F to help reduce room temperatures. If this strategy is practiced, a source of light is needed somewhere in the room. Some producers report lactation failure if sows and litters are subjected to total darkness on a continual basis.
Prenatal mortality: Mortality at this stage may be as high as 40 percent. The bulk of this embryo loss occurs during the first 2 to 3 weeks following breeding. Factors associated with embryo loss include stage of pregnancy, disease, age of dam, genetic factors, nutrition, external environment, intrauterine environment, and stress. The following steps to avoid increased embryo mortality should be taken throughout the entire year; however, during a critical time when pigs are under extreme heat-related stress, following these suggestions is imperative:
1. Avoid late estrual inseminations: The simplest way to prevent late estrual inseminations is to ignore "target" number of inseminations and breed females totally on the basis on a strong standing heat response. Another way to reduce mistimed inseminations is to determine the average estrus
length in your weaned sows, gilts, and repeat breeders and based on these averages, shorten the last insemination interval. For example if you normally can service sows AM-AM-AM, change your schedule to AM-AM/PM. Thorough heat-checking prior to performing subsequent inseminations will also help prevent poorly timed late artificial inseminations, which may interfere with uterine preparation for implantation.
2. Minimize unnecessary stress by mixing females only at weaning: Once fertilization occurs in the oviducts, pig embryos descend into the uterus very quickly; however, implantation does not occur until day 12 and full attachment until day 18. During this time, the pig is highly susceptible to stress factors, such as movement and temperature. If females are to be mixed, this should be performed on the day of weaning to prevent unnecessary stress on the animal. Any unnecessary stress following breeding can result in embryo detachment and loss.
3. Refrain from, or even stop, moving females in gestation to different locations: After breeding and around day 30 of pregnancy, females can be moved to a different location; however, mixing sows and gilts any time during or following breeding greatly increases the chances of subsequent embryo mortality. Temperature changes are likely to elevate embryo mortality, and steps to prevent environmental extremes should be taken to avoid unnecessary stress during early pregnancy.
4. Provide a good, level plane of nutrition before, during, and after breeding: Pre-mating nutritional status appears to be a greater determinant of embryo numbers and survival than the post-mating diet in gilts. This strategy requires "flushing" gilts with an extra 1 to 2 pounds of feed during the estrus cycle prior to mating. This can be attempted for sows as well, even though most post-weaned sows will voluntarily restrict their own feed intake. However, various studies have indicated that high feed intake during the first 30 days following breeding may also have a negative impact the embryo survival rates. Therefore, sows and gilts should be maintained on a level feed plane at or slightly above maintenance following breeding. There are no extra measures to take in feeding during periods of heat stress with the exception of ensuring that the female is consuming feed daily (hopefully around 4-5 pounds per feeding, depending on diet formulation). Appropriate action to boost appetite may be required, similar to procedures used during lactation.