Effect of Nutrient Restriction and Realimentation on Growth and Metabolic Responses of Shorn Suffolk, Gulf Coast Native, and Crossbred Lambs

• Published in: The Professional animal scientist Vol. 15; no. 2; pp. 112 - 115
• Main Authors: White, T.W., Fernandez, J.M., Walz, L.S., Gentry, L.R., Chapa, A.M., Blouin, D.C., McNitt, J.I., Stanton, T.L.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.06.1999; American Registry of Professional Animal Scientists
• Subjects: blood glucose; blood lipids; blood plasma; blood protein; breed differences; cortisol; crossbred progeny; dry matter; feed intake; Lambs; liveweight gain; native livestock; Nutrient Restriction; Realimentation; repletion; restricted feeding; sheep breeds; Suffolk (sheep breed); thyroxine; urea; Realimentation; Lambs; Nutrient Restriction
• ISSN: 1080-7446; 1525-318X
• DOI: 10.15232/S1080-7446(15)31738-1

Growth and plasma hormone and metabolite levels were used to compare the effects of nutrient restriction and realimentation on six Suffolk (S), six Gulf Coast Native, (G) and seven S×G crossbred lambs. Shorn lambs were individually fed a 10% CP diet consisting of 20% cottonseed hulls, 74% ground corn, 1% soybean meal, 3% fish meal, 1.1% oyster shell flour, 0.5% urea, and 0.4% trace mineral salt and vitamin A, D, and E mixture. Lambs were fed at 110% of maintenance, 200% of maintenance, or had ad libitum access to feed during periods 1, 2, and 3, respectively. Each period was 28 d in length. Breed did not affect (P>0.25) weight change during nutrient restriction or realimentation. All lambs lost weight during the first period. The calculated NEm of weight loss and 10% feed intake above maintenance suggests an 88% increase in maintenance energy requirement at 11.6 ± 0.9°C average temperature. Similar shorn G lambs maintained weight even though fed at 200% of maintenance, suggesting a 99% increase in NEm. Plasma cortisol was lower (P<0.05) and thyroxine higher (P<0.05) in S than G or S×G lambs. Plasma cortisol levels were stable from d 14 through 42 declining to d 70 and increasing on d 84. Plasma thyroxine, urea N, and NEFA concentrations followed a similar pattern. There were differences between breed in plasma hormone levels but not plasma metabolite or weight change. Maintenance energy requirement of shorn lambs was increased.