Effects of Standardized Ileal Digestible Lysine Intake during Lactation on Litter and Reproductive Performance of Gilts.

This experiment was conducted to determine the effects of Standardized Ileal Digestible (SID) lysine intake during lactation on litter and reproductive performance of gilts. A total of 784 gilts (PIC Camborough) were used in a 21-d lactation. Gilt was considered the experimental unit and all fostering was recorded and occurred within 24 hours post-farrowing. All litters were standardized to 13 nursing piglets within 24 hours of farrowing and prior to gilts starting the trial. Gilts were offered 2.3 kg/d of common gestation diet from entry into farrowing rooms until farrowing day. Gilts were allowed ad libitum access to feed from day 2 post farrowing until weaning. Dietary treatments were: 0.90, 1.03, 1.15, 1.28, and 1.40% SID Lys. Two corn-soybean meal based diets with 3,322 kcal ME/kg were formulated with the lowest and highest SID Lys levels and blended with a computerized system to achieve the intermediate SID Lys levels. L-Lys in the diets ranged from 0.25 to 0.44% and soybean meal ranged from 23 to 38%. Data was fit using the GLIMMIX procedure of SAS^© (Cary, NC) with SID Lys treatment as fixed effect and farrowing week and room used as random effects. Amino acid analysis confirmed total formulated values. Gilts weighed 199.7 kg ± 2.13 post-farrowing, which likely contributed to a low overall lactation feed intake of 4.6 kg/d ± 0.11, which may have caused gilts to be energy limited in this study. Increasing dietary lysine showed a reduction in backfat at weaning (linear, P=0.026), a significant increase in total litter weight at weaning (linear, P=0.075), a significant increase in litter weight gain (linear, P=0.057), and a significant improvement in lactation litter gain:feed (linear, P=0.029). In conclusion, increasing lysine intake of gilts during lactation maximized litter growth in this study up to 63 grams of SID Lys intake per day despite an apparent energy limitation.

	SID Lysine, %						Probability, P<
	0.9	1.03	1.15	1.28	1.4	SEM	Linear	Quadratic
Sow BW change, kg	-5.9	-6.6	-7.1	-5.7	-7.1	1.4	0.668	0.912
Backfat at weaning, cm	1.3	1.28	1.29	1.26	1.22	0.028	0.026	0.408
Litter weight gain, kg/d	2.37	2.38	2.37	2.49	2.44	0.044	0.057	0.993
ADFI, kg	4.68	4.69	4.53	4.65	4.53	0.107	0.526	0.994
g of SID Lys intake, g/d	42.0	48.2	52.2	59.2	63.4	1.08	0.001	0.889
Subsequent total born, n	13.9	14.4	14.6	14.1	14.8	0.37	0.221	0.832