Genetic Improvement and Nutrition Trends

Introduction

Genetic advancement continues to deliver outstanding results at the commercial level with an accelerating rate of improvement. The use of large scale commercial nutrition trials allows us to determine nutrient specifications to maximize the profitability for swine producers worldwide. This article will cover the latest improvements in genetics and the changes associated with it in regards to nutrition.

Past, present, and future

In 2006, the average number of weaned pigs per mated female per year was 21.5 in the United States (Pig Champ, 2006). Today, the top 10% of the farms are above 30 weaned pigs per mated female per year, with an average of 26.2 (PIC internal database; 700,000 sows). With the use of relationship-based selection by genomic technology, the rate of progress of genetic selection of PIC pigs has increased by over 35% beginning in 2014 (Figure 1) and is starting to be realized by customers this year as the rollover of the replacements gilts occurs through the multiplication and commercial flows. With the use of this and other new technologies in the pipeline, it can be suggested that by 2062 a commercial female might be expected to wean 56 pigs.

Table 1 shows the rates of changes of genetic improvement for different traits of PIC pigs in the last 5, 3, and 1 year/s.

Increasing prolificacy, if not balanced for potentially associated negative impacts, may increase the incidence of light weight low quality piglets. PIC has long selected for quality weaned pigs with superior growth performance. PIC has increased the focus on this area by including individual piglet birth weight (Figure 2) in the improvement program (with total born, still born, pre-weaning mortality and weaning weight). There was a reduction in individual piglet birth weight of about 100 g from 2006 to 2013, and this reduction seems to be fully reverted now at the genetic nucleus level. This type of program is believed to allow for an increase on the number and weight of weaned pigs/sow/year and maintain exceptional growing pig performance.

Table 1. Rates of changes of genetic improvement for different traits of PIC pigs in the last 5, 3, and 1 year/s.

Feed cost

Feed cost is largely dependent on corn and soybean prices. Figures 3 to 5 show the dramatic changes in commodities and feed cost comparing years 2000-2006 to 2007-2016. Corn has changed from about $2 to 3/bu in mid-2000s to $4 to 5/bu in 2010s and currently flat at $3.5 to $4/bu. Soybean meal has changed from $200/ton in mid-2000s to about $360 in 2010s with a decrease to $280-300/ton in early 2016, and currently at $350 to $400 in mid-2016.

Following commodities trends, feed cost in mid-2000s was 60% of 2015’s feed cost with an increase from 2007 to 2014 being about 115% of 2015’s feed cost. There was a recent decrease where 2016 and 2017 are expected to have similar feed costs compared to 2015 (Langemeier, 2016).

Whole herd feed efficiency

The breeding herd can represent 10-15% of the total feed cost of a breeding to finish operation. A series of recent research with PIC sows related to late gestating feed management has shown that the increase of feed in late gestation has modest (40 g) impact on individual birth weight of piglets from gilts and little to no impact on birth weight of litters from sows (Shelton et al., 2009, Soto et al., 2011, Ampaire and Levesque, 2016, Greiner et al., 2016, Gonçalves et al., 2016a). There has also been documented in a large-scale study, an increase in stillborn rate in litters from sows that were fed 6.75 Mcal NE/d instead of 4.50 Mcal NE/d in late gestation (Gonçalves et al., 2016a). Therefore, it is currently recommended to only increase the amount of feed in late gestation to gilts, but not sows. It is recommended that gilts during gestation are fed 4.50 Mcal NE/d until d 90 of gestation and then 6.75 Mcal NE/d, whereas for sows it is recommended to feed 5.4 Mcal NE/d until d 28 and 4.50 Mcal NE/d afterwards. This shows the high efficiency of PIC females and minimizes the amount of feed per sow per year as well as the amount of breeding herd feed per weaned pig.

Lysine requirement update

There was a dramatic increase in lean gain and efficiency of PIC pigs in the last decade. With an increase in growth rate and improved feed efficiency it is expected that, overtime, the nutrient concentration of the diets need to be updated to match the pig’s needs to achieve its genetic potential. Lysine (Lys) is, typically, the first limiting amino acid in swine diets. Thus, a meta-analysis was conducted to evaluate the Standardized Ileal Digestible Lys requirement for PIC pigs. A total of 27 commercial experiments were used in the meta-analysis with a total of 45,102 pigs. Requirement estimation models were implemented as per Gonçalves et al. (2016b). Due to the high potential for protein deposition, adequate amino acid supply is important for successful production of PIC pigs. Amino acid deficient diets can have negative influences on growth performance and behavior (Fraser, 1987, NRC, 2012). Figure 6 shows the relative changes in Lys requirement from 2008 versus 2016 meta-analysis. When implementing these changes, all other amino acids should be increased to maintain the appropriate ratio to Lys.

Thus, lysine requirements for current PIC pigs are greater than in the past. This is probably due to increased rate of growth and improved feed efficiency from current lines.

Conclusion

Reproductive and growth performance traits have made great strides in the last decade through genetic improvement. The exponential increase in availability of cutting-edge genetic technologies is continuing to accelerate the rates of genetic improvement. In addition large-scale commercial nutrition research has allowed us to capture this genetic potential and increase profitability for swine producers around the globe. The increase in feed cost in the last decade has prompted swine producers to continue to focus on whole herd feed efficiency. Finally, with the improved rate of gain and feed efficiency, the lysine level fed should be updated to maintain a similar amount of lysine per unit of gain.