Evaluation of gender and lysine during the nursery period

¹ NCCC-42 Committee on Swine Nutrition

^* To whom correspondence should be addressed. E-mail: hillgre{at}msu.edu.

	Abstract

Split-gender feeding in the grow-finish period of swine production has become a common practice during the last decade because of the different growth rates, feed efficiencies, and perhaps different nutrient needs between gilts and barrows. However, due to various weaning strategies, it has not been adequately evaluated in the nursery. The objectives of our research were to determine: (1) if gilts and barrows respond similarly to increased protein (Lys) after weaning, and (2) if the current estimated NRC Lys requirements are adequate. Six experiment stations (KS, KY, MI, MN, OH, and SD) utilized 748 pigs (6.7 kg; 19.4 ± 1.1 d). The pigs were allotted to 4 treatments with 32 replications (5 to 7 pigs/pen) per treatment in a randomized complete block design. Barrows and gilts were penned separately, and complex nursery diets were fed in 3 phases (d 1 to 7, 8 to 21, and 22 to 35). Lysine was provided at NRC estimated requirements or at 0.20% greater than the requirement (1.35 vs. 1.55%, 1.25 vs. 1.45%, and 1.15 vs. 1.35% for the three phases, respectively). Pigs and feed were weighed initially and at the end of each phase. The results demonstrated that gender did not affect ADG, ADFI, or G:F in any phase or during the 35-d study (453 vs. 452 g/d, 674 vs. 675 g/d, and 0.673 vs. 0.671 g/g for barrows and gilts, respectively). The higher Lys concentration improved ADG in phase 3 (628 vs. 589 g/d; P < 0.001) and overall (465 vs. 441 g/d; P < 0.001) compared with pigs fed the NRC Lys estimated requirements. Increased Lys in the diet increased ADFI in phase 2 (P < 0.05), but not in the other phases or for the overall 35-d study. Gain:feed was improved by feeding higher lysine concentrations in phase 2 (0.785 vs. 0.704 g/g ; P < 0.001) and in the overall 35-d experiment (0.695 vs. 0.649 g/g; P < 0.001). There was no evidence of a gender x Lys interaction (P = 0.33) for any of the response variables during any of the phases or overall. Our results demonstrate that increasing Lys concentrations in nursery diets can improve pig performance of both genders, and there seems to be no benefit to split-gender feeding when several different genotypes are fed in this nursery study.

Key Words: gender, lysine, nursery pig, pig