Abstract
This research aimed to define the energy requirement of Dorper and Hu Hybrid F1 ewes 20 to 50 kg of body weight, furthermore to study energy requirement changes with age and evaluate the effect of age on energy requirement parameters. In comparative slaughter trial, thirty animals were divided into three dry matter intake treatments (ad libitum, n = 18; low restricted, n = 6; high restricted, n = 6), and were all slaughtered as baseline, intermediate, and final slaughter groups, to calculate body chemical components and energy retained. In digestibility trial, twelve ewes were housed in individual metabolic cages and randomly assigned to three feeding treatments in accordance with the design of a comparative slaughter trial, to evaluate dietary energetic values at different feed intake levels. The combined data indicated that, with increasing age, the net energy requirement for maintenance (NEm) decreased from 260.62±13.21 to 250.61±11.79 kJ/kg0.75 of shrunk body weight (SBW)/d, and metabolizable energy requirement for maintenance (MEm) decreased from 401.99±20.31 to 371.23±17.47 kJ/kg0.75 of SBW/d. Partial efficiency of ME utilization for maintenance (km, 0.65 vs 0.68) and growth (kg, 0.42 vs 0.41) did not differ (p>0.05) due to age; At the similar condition of average daily gain, net energy requirements for growth (NEg) and metabolizable energy requirements for growth (MEg) for ewes during late fattening period were 23% and 25% greater than corresponding values of ewes during early fattening period. In conclusion, the effect of age upon energy requirement parameters in the present study were similar in tendency with previous recommendations, values of energy requirement for growth (NEg and MEg) for Dorper and Hu crossbred female lambs ranged between the NRC (2007) recommendation for early and later maturating growing sheep.
Highlights
Nutritional management would usually be expected to start with the knowledge of nutrient requirement, an understanding of the nutrient requirement of various sheep breeds is essential for the nutritional management
The selected in accordance with procedures approved by the Guide for level of the DMI was intended to make the average daily the Care and Use of Laboratory Animals prepared by the gain (ADG) of ewes under each nutrition treatment to be Ethics Committee of Nanjing Agricultural University
Results of our study suggest that Net energy requirement for growth (NEg) values of ewes with BW ranging from 20 to 35 kg at ADG of 0 to 300 g scaled from 1.25 to 4.55 MJ/d (Table 6), which were obtained from regression equations between empty body weight (EBW) and body energy content: Log10 (Final body energy, MJ) = 0.618(±0.143)+1.337(±0.088)× Log10 (EBW, kg), (r2 = 0.92; n = 17, p
Summary
Nutritional management would usually be expected to start with the knowledge of nutrient requirement, an understanding of the nutrient requirement of various sheep breeds is essential for the nutritional management. Some nutritional systems, such as National Research Councils (NRC), Agricultural Research Councils (ARC) and Commonwealth Scientific and Industrial Research Organization (CSIRO) have reported studies on nutrient. The difference in nutrient requirements are widely varying even among species. There is no report on the nutrient requirements for Dorper and Hu hybrid F1 sheep, which are characterized by their high fecundity and rapid growth. The objective of this study was to determined energy requirements for maintenance and growth of these crossbred growing ewes using a comparative slaughter
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