Abstract
Abstract Due to packing plant closures or slow-downs, many producers needed to examine ways to reduce average daily gain (ADG) of finishing pigs. Therefore, a total of 1,080 pigs (L337 × 1050, PIC; initially 32.0 kg) were used in a 119-d trial to evaluate the effects of reducing dietary standardized ileal digestibility (SID) Lys and SID Trp:Lys ratio to slow growth of finishing pigs in a commercial setting. Pigs were randomly allotted in weight blocks to 1 of 4 dietary regimens with 27 pigs/pen and 10 replications/regimen. Pigs were fed a control regimen (100% of the estimated SID Lys requirement for pigs in this facility) formulated to contain 1.10, 1.01, 0.91, 0.83, 0.79, 0.71 and 0.67% SID Lys from 32 to 42, 42 to 51, 51 to 72, 72 to 85, 85 to 97, 97 to 112, and, 112 to 130 kg, respectively. Two other regimens contained 90 or 80% of the Lys estimate. These 3 regimes were formulated to a SID Trp:Lys ratio of 19% except for the last dietary phase that contained 17% SID Trp:Lys ratio. The fourth regimen contained 80% of the SID Lys estimate with 16% SID Trp:Lys in all phases. The statistical model included fixed effects of treatment, random effect of block, linear and quadratic effects of SID Lys and pairwise comparison of the two 80% treatments. Overall, decreasing SID Lys decreased (linear, P < 0.01) ADG and final body weight (BW) and tended (P < 0.10) to decrease gain:feed ratio (G:F). Reducing the Trp:Lys ratio decreased (P = 0.014) ADG and final BW compared to pigs fed diets with 80% SID Lys with higher SID Trp:Lys. In summary, decreasing SID Lys reduced ADG and feeding a reduced SID Trp:Lys ratio resulted in a further decrease in ADG of grow-finish pigs.
Highlights
During the COVID-19 outbreak in 2020, the swine industry was forced to find dietary strategies to decrease growth rate of pigs due to plant closures and slowdowns
A total of 1,080 finishing pigs (327 × 1050, PIC; initially 71.3 ± 1.91 lb) were used in a 119-d growth trial to evaluate the effects of reducing the dietary SID Lys and SID Trp:Lys ratio on growth performance to find strategies to reduce growth rate of pigs during the grow-finish period
Pigs were allotted by initial BW and randomly assigned to 1 of 4 dietary treatments in a completely randomized block design with 27 pigs per pen and 10 pens per treatment
Summary
During the COVID-19 outbreak in 2020, the swine industry was forced to find dietary strategies to decrease growth rate of pigs due to plant closures and slowdowns. Kansas State University Agricultural Experiment Station and Cooperative Extension Service is the first limiting amino acid in corn soybean-meal-based diets. Decreasing the level of Lys in the diet will decrease protein deposition of the pig and, reduce overall growth rate. The second limiting amino acid in diets high in corn protein is Trp. Previous research has shown that reducing Trp in the diet from 19 to 16% of Lys will reduce feed intake, weight gain, and worsen feed efficiency (F/G).. Reducing Lys along with Trp could be a potential approach to further slowdown growth rate of pigs to increase the amount of time needed to reach market weights Previous research has shown that reducing Trp in the diet from 19 to 16% of Lys will reduce feed intake, weight gain, and worsen feed efficiency (F/G). reducing Lys along with Trp could be a potential approach to further slowdown growth rate of pigs to increase the amount of time needed to reach market weights
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