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

Fifty gilts [initial BW 190.7 ± 4.2 kg] were recruited on d 85 of gestation and were used until d 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 five 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 d 85 and 110 of gestation and d 1 and 19 (weaning) after farrowing. Offspring were weighed on d 1 and 19 of age. On lactation d 1 (approx. 24 h after farrowing), colostrum, gilt plasma, and plasma from two median body weight (BW) piglets were collected and on d 19, plasma from each gilt and two median BW piglets per litter were collected for determination of Ig concentrations. Contrast statements were used to assess 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 pre-weaning 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 d 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 d 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 pre-weaning growth rates and body weight at weaning. Therefore, maternal feeding of HY could be used as a strategy to improve offspring immunocompetence and BW at weaning, with possible carry-over benefits for the post-weaning phase.