GILT DEVELOPMENT AND LONGEVITY
Posted in: Pork Insight Articles, Production by admin on May 12, 2017
The data suggest a split on the impact of fast gilt growth rate on reduced longevity. Based on the large data sets and variety of farms and genetics included, it is more likely that as long as gilts are within a desired range for growth, puberty and even longevity may not be the issue. However, both fertility and longevity can be influenced by gilt parameters at time of breeding which would have consequences for gestation and lactation performance. The data also strongly suggest that very low growth rates (<500 g/d) are less likely arise in modern production systems today. These gilts would be far below weight and should not be selected for the gilt pool. Farms that do observe problems with excessive body condition as a result of fast growth rates, can choose to limit feed access or change diet as long as restriction of energy is not below 75% of ad libitum, and protein is not limiting. Several studies implicate age at first farrowing, first litter size, and litter weaning weight as key measures for gilt longevity. First litter production is an important milestone for gilts and relies on breeding decisions and management of the female. The factors involved in litter production include gilt fertility at estrus, her ovulation rate, fertilization rate, embryo survival and uterine capacity. Some of these processes are complex, and therefore farms should focus on what can be assessed and controlled by management. The considerable body of evidence implicating troublesome variation in estrus expression suggests problems in how farms deal with this problem and how estrus expression is performed in gilts. The genetic and seasonal effects on estrus symptoms also suggest that more stringent culling could be helpful. However, industry data indicates high performance is possible and not infrequent for early age at puberty and gilt puberty induction. Problems then appear to be further downstream when gilts fail to farrow early in their lifetime, when they produce a small litter in the first farrowing, or when they wean a light litter in their first parity.