Dose-response of inactivated yeast in diets of late gestating and lactating gilts on immunoglobulin transfer and offspring preweaning growth performance.

Fifty gilts (initial body weight [BW] 190.7 ± 4.2 kg) were recruited on day 85 of gestation and were used until day 19 of lactation to assess the dose-response of inactivated yeast via hydrolyzation (HY) inclusion on offspring growth and immunoglobulin (Ig) transfer prior to weaning. Gilts were assigned to one of the 5 experimental diets: a control with no HY (HY0) or inclusion of 0.25% (HY0.25), 0.5% (HY0.5), 1.0% (HY1.0), or 1.2% (HY1.2) HY. Gilts were weighed on days 85 and 110 of gestation and days 1 and 19 (weaning) after farrowing. Offspring were weighed on days 1 and 19 of age. On lactation day 1 (approximately 24 h after farrowing), colostrum, gilt plasma, and plasma from 2 median BW piglets were collected and on day 19, plasma from each gilt and 2 median BW piglets per litter were collected for determination of Ig concentrations. Contrast statements were used to assess the linear, quadratic, cubic, and quartic effects of HY inclusion. The inclusion of HY had minimal effects on gilt BW or litter characteristics at birth (total number born and born alive, piglet birth weight). Lactation average daily feed intake of the gilts tended to increase then decrease with increasing HY inclusion (quadratic; P = 0.085). Piglet preweaning average daily gain (linear, quadratic, and quartic; P < 0.05) and BW at weaning (quadratic and quartic; P < 0.05) increased then decreased with increasing HY inclusion. On lactation day 1, colostrum and gilt plasma Ig concentrations were not affected by dietary treatment (P > 0.10) but piglet IgA and IgM decreased then increased with HY inclusion level (cubic; P < 0.05). On lactation day 19, piglet plasma IgG tended to increase with HY inclusion (linear; P = 0.099). In summary, increasing HY inclusion in late gestating and lactating gilt diets improved immune transfer in the first 24 h after birth and piglet preweaning growth rates and BW at weaning. Therefore, maternal feeding of HY could be used as a strategy to improve offspring immunocompetence and BW at weaning, with possible carryover benefits for the postweaning phase.