148 PIGLET GROWTH AND BLOOD COMPONENTS DURING LACTATION FOLLOWING RECIPROCAL EMBRYO TRANSFER BETWEEN MEISHAN AND WHITE CROSSBRED GILTS
Authors: Miles J. R. , Vallet J. L. , Ford J. J. , Freking B. A. , Cushman R. A. , Oliver W. T. , Christenson R. K. 
Published: August 2011

Sow productivity has a significant economic impact on the swine industry and is influenced by several factors, including preweaning piglet mortality. In Western breeds, low birth weight piglets exhibit the greatest susceptibility to preweaning mortality. In contrast, Meishan (MS) piglets have decreased birth weights but lower preweaning mortality rates, suggesting that birth weight is not the sole component of preweaning survival. The objective of the current study was to determine the contributions of the maternal and piglet breed and their interactions on piglet growth and blood components pertaining to survivability during lactation following reciprocal embryo transfer between MS and White crossbred (WC) gilts. Twenty-five successful pregnancies were produced by embryo transfer in 2 farrowing seasons that represented all maternal and piglet breed combinations; MS × MS (n = 4 litters), MS × WC (n = 7 litters), WC × MS (n = 7 litters), and WC × WC (n = 7 litters). At Day 1, 10, and weaning (average weaning age = 18 days), piglets (n = 147, 97, and 94, respectively at Day 1, 10, and weaning) were weighed and blood samples were taken. Hematocrit, hemoglobin, glucose, nitrogen, nonesterified fatty acids, albumin, and cortisol were measured in all blood samples. All data were analysed for ANOVA using mixed model procedures. Piglet weights were greater (P < 0.001) throughout lactation in piglets from WC dams regardless of piglet breed. As a result, average daily gains from Days 1 to 10 and weaning were greater (P < 0.05) in piglets from WC dams. There were significant (P < 0.001) maternal × piglet × day interactions for hematocrit and hemoglobin levels in which levels were greatest at Day 1 in MS piglets from WC dams and at Day 10 in MS piglets from MS dams but decreased in WC piglets from WC dams at Day 1. Glucose was greater (P < 0.05) at Day 1 in piglets from WC dams regardless of piglet breed but was greater (P < 0.05) at weaning in WC piglets regardless of maternal breed. Nitrogen was similar at Day 1 for all maternal and piglet breed combinations, but at Day 10 and weaning, nitrogen levels were greater (P < 0.001) in MS piglets regardless of maternal breed. Nonesterified fatty acid was greater throughout lactation in piglets from MS dams irrespective of piglet breed. Albumin was greater (P < 0.05) in MS piglets throughout lactation regardless of maternal breed. Cortisol was not different between the maternal and piglet breed combinations throughout lactation, but cortisol was greater (P < 0.001) at Day 1 compared with Day 10 and weaning. This study demonstrated that piglet growth during lactation was influenced more by maternal breed in favor of WC dams, which supports previous crossbreeding studies. However, blood components pertaining to survivability displayed complex interactions between the piglet and maternal breed, which may signify possible mechanisms for improved preweaning survivability of MS pigs.