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Sow performance in response to dietary betaine fed in lactation and weaning-to-35 d post-insemination during moderate heat stress
This study was conducted to evaluate the effect of feeding dietary betaine during lactation and weaning-to-35 d post-insemination on sow reproductive performance during summer months. A total of 649 sows were balanced by parity (169, 153, and 327 sows representing parity 1, 2, and 3 to 6) and assigned within parity to a 2 x 2 factorial arrangement of treatments. Factors included betaine concentration: 1) in lactation (0 or 0.2%) and 2) from weaning through early gestation (0 or 0.2%). Lactation diets were corn-soybean meal based with 10% rice bran and 6.0% wheat middlings, and formulated to contain 651 ppm of choline, 3.31 g SID Lys/Mcal ME and a SID Met+Cys:Lys ratio of 0.56. Gestation diets were corn-soybean meal based with 30% wheat middlings, 15% rice bran, and formulated to contain 651 ppm choline, 1.82 g SID Lys/Mcal ME and a SID Met+Cys:Lys ratio of 0.69. Sows were started on lactation diets the day they farrowed. Sows that did not return to estrus within 14 d after weaning were removed from further study. Data were analyzed using the MIXED procedure of SAS and GLIMMIX was used for dichotomous variables using the logit link function. Lactation length was used as a covariate for percentage of sows that returned to estrus. Average room temperature was 25.2±2°C during lactation and 24.1±3°C during the weaning-to-35 d post-insemination period. Betaine fed in lactation tended to reduce feed intake (P=0.07; 3.52 vs. 3.72 kg/d), and reduced litter gain weight (P=0.03; 48.9 vs. 51.2 kg) and rectal temperature (P=0.04; 39.35 vs. 39.70°C) in parity 1 and 2 sows, but not parity 3 or older sows. Feeding betaine after weaning tended to increase (P=0.08) the percentage of sows returning to estrus within 14 d (87.0 vs. 81.7%). Wean-to-estrus interval tended (P=0.07) to be reduced for parity 1 sows fed betaine (4.53 vs. 4.91 d). Conception rate was numerically reduced for parity 1 sows when betaine was fed during lactation (P=0.17; 71.9 vs. 80.7%). When betaine was fed to parity 3 and older sows from weaning-to-35 d post-insemination, conception rate was numerically increased (P=0.14; 87.0 vs. 80.8%). Results suggest that the use of 0.2% betaine during lactation did not benefit sow performance and conception. However, feeding betaine after weaning to parity 3 or older sows may increase the number of sows that conceived.
Keywords: betaine, conception rate, sow performance.