Dietary lysine requirement of sows increases in late gestation1

• Published in: Journal of animal science 2012-12, Vol.90 (13), p.4896-4904
• Main Authors: Samuel, R. S., Moehn, S., Pencharz, P. B., Ball, R. O.
• Format: Article
• Language: English
• Subjects: Animal sciences; Dietary supplements; Hogs; Physical growth
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jas.2011-4583

Current AA recommendations for sows are to provide a fixed amount of AA intake throughout gestation; however, the demand for nutrients changes from maternal lean tissue in early gestation (EG) to fetal and mammary growth in late gestation (LG). The objective of this study was to determine the Lys requirement in EG (d 24 to 45) and LG (d 86 to 110) using the indicator AA oxidation method with simultaneous determination of heat production. Each of 7 Large White x Landrace sows received 6 diets in random order in both EG and LG. Three semisynthetic diets (14.0 MJ ME/ kg) based on corn were formulated and mixed to produce a basal diet (60% of 1998 NRC Lys requirement) and high diets for EG and LG (150% and 185% of 1998 NRC Lys requirements, respectively). The 6 test diets provided Lys intakes of 7.5 to 19.3 g/d in EG and 8.1 to 23.7 g/d in LG. Sows were placed in respiration chambers, and expired air and blood were collected every 30 min for 5.5 h. The tracer AA, l-[1-^sup 13^C]Phe, was given orally at a rate of 2 mg/(kg BW h) over the last 4 h, divided into 8, 0.5-h meals. Expired air was measured for 13CO2 enrichment, and plasma was measured for l-[1-^sup 13^C]Phe enrichment and free Lys concentration. Background ^sup 13^CO^sub 2^ was subtracted from plateau ^sup 13^CO^sub 2^ enrichment. Requirements were determined using a 2-phase nonlinear model. Mean maternal BW gain in gestation (43.7 kg; pooled SE, 1.2 kg), litter size (14.6 total born piglets; pooled SE, 0.8), and litter weight (19.4 kg; pooled SE, 0.9 kg) did not differ between parities. Sow weight gain and BW was greater (P = 0.001) in LG than EG. Lysine requirement was 9.4 and 17.4 g/d in EG and LG, respectively. Phenylalanine retention in LG was maximized at a Lys intake of 17.7 g/d. Heat production was more (P = 0.069) and energy retention less (P = 0.019) in LG than EG. Energy retention in LG was not different from 0. Quantitative Phe kinetics in EG were not affected by Lys intake. In LG, Phe retention increased with Lys intake (P = 0.004), whereas Phe oxidation decreased (P = 0.005). The Lys requirement was determined to be less than current recommendations in EG and more than current recommendations in LG. To meet the change in requirements, diets with increased lysine content are needed in LG. Increasing the feed allowance in LG is necessary to maintain a positive energy balance throughout gestation. [PUBLICATION ABSTRACT]