September 7, 2023
By Mark Knauer, North Carolina State University and Jeff Wiegert, Texas A&M University
It is well known that piglet colostrum intake at birth is largely related to piglet survival during lactation. Further, increased colostrum consumption has also been reported to enhance nursery survival. Given the importance of colostrum, have geneticists forgotten about it? The answer is perhaps yes and no.
Industry data shows litter size has increased over the past 20 years suggesting that genetic selection for more piglets per litter has been successful. Increasing litter size is problematic as it reduces colostrum consumption per piglet and increases the variation in colostrum consumption within a litter (Table 1).
Fortunately, many genetic companies have increased functional teat count over the last 20 years. Data suggests increasing functional teat count helps counter the impact of larger litter sizes as an increase in functional teat count augments sow colostrum output and reduces variation in piglet colostrum intake (Table 1).
Reducing variation in piglet colostrum intake should enhance piglet survival, as fewer piglets would fall below a threshold level of colostrum needed to thrive. Unfortunately, geneticists have increased litter size at a faster rate than functional teat number. Hence, the average piglet born today likely has access to less colostrum than a piglet born 20 years ago.
How can we genetically enhance colostrum production?
Measuring sow colostrum output is very labor intensive. Yet there are several traits, associated with colostrum production, which we may be able to leverage to enhance sow colostrum yield.
Functional teat number – Functional teat number will likely continue to increase in the U.S. and we expect the ratio of functional teats to litter size to improve as geneticists look to plateau litter size in the future. A potential problem with increasing functional teat number is that we may increase sow body length, which could be unfavorable given the length of many of our farrowing stalls in the U.S. today.
Age at puberty – There is growing evidence that increased colostrum production hastens puberty attainment. The USDA reported gilts that consumed higher levels of colostrum as piglets reached puberty at a younger age. More recently, Wiegert and Knauer reported sows from a genetic line selected for young age at puberty had increased colostrum production when compared to a control genetic line. However, genetic selection for age at puberty is currently difficult as age at puberty can be a challenging trait to capture.
Weaning weight – Weaning weight is the trait that many or most of the major genetic companies seem to be forgetting to select for in their maternal genetic lines. Associations between litter colostrum intake with litter weaning weight and piglet survival (litter size at weaning of the biological sow ÷ total number born) are shown in Figures 1 and 2, respectively. These figures suggest 80% of the 295 litters in this data set did not consume enough colostrum to maximize litter weaning weight or piglet survival.
The component traits of litter weaning weight are piglet vitality, sow colostrum production, piglet birth weight and sow milk yield. In 2017, Kennedy showed litter weaning weight is essentially synonymous with piglet quality. Hence, if your production system needs to increase the percentage full-value piglets at weaning and at nursery entry, your genetic supplier can help by enhancing weaning weights in their Landrace and Large White populations.
In terms of nursery throughput, average piglet weaning weight and weaning age have been reported to explain the majority of nursery growth rate. Hence, genetic selection for weaning weight offers geneticists an opportunity to enhance sow colostrum production, full-value piglets at weaning, nursery throughput and pounds marketed through a production system.
Increases in litter size will not be of benefit unless there are sufficient nutrients to support additional piglets. Hence, going forward the industry needs to enhance sow colostrum yield to maximize throughput and profitability. It is going to take a team effort to enhance sow colostrum output. Hence there is opportunity for scientists in nutrition and other disciplines to work together to enhance sow colostrum production and piglet nutrient access. Questions and comments can be directed to Mark Knauer at [email protected].
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