FAILURE OF DIETARY AMINO-ACID SUPPLEMENTATION AT WEANING TO INFLUENCEREPRODUCTIVE TRAITS OF SOWS

Primiparous and multiparous sows received a single dietary supplement of either L-tyrosine, L-phenylalanine, or L-glutamate in their feed on the day after weaning and effects on various reproductive traits were evaluated in three experiments. In Exp. 1 and 2, sows received either 0 (control; n = 22 and 64, respectively) or 100 mg of L-tyrosine/kg B W (n = 24 and 62, respectively) on the day after weaning. In Exp. 1, d ays from weaning to estrus (5.5 +/- .3 vs 5.3 +/- .3 d) and ovulation rate (15.6 +/- .9 vs 15.6 +/- 1) were similar in control and tyrosine- supplemented sows. In Exp. 2, interval from weaning to 'estrus was ext ended (P < .01) in tyrosine-supplemented sows (6.4 +/- .5 d) compared with controls (4.5 +/- .5 d), but this was due to long return interval s in 7 of 62 tyrosine-supplemented sows. Total number of pigs born (10 .2 +/- .4 vs 10.0 +/- .4) was similar in control and tyrosine-suppleme nted sows. In Exp. 3, sows received either no supplemental amino acids (n = 31) or their diet was supplemented with 100 mg/kg BW of either L -tyrosine (n = 31), L-phenylalanine (n = 33), or L-glutamate (n = 32). Neither days from weaning to estrus nor subsequent farrowing traits w ere altered in sows that received supplemental amino acids on the day after weaning. In conclusion, a single dietary supplementation of eith er tyrosine, phenylalanine, or glutamate to sows on the day after wean ing failed to improve interval from weaning to estrus, ovulation rate, or litter traits at subsequent farrowing.