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Energy and nitrogen retention in milk-fed lambs

AutorMantecón, Ángel R. ; Peláez, Rodrigo ; Ovejero, Francisco J.
Fecha de publicación1987
EditorBritish Society of Animal Science
CitaciónBSAP Winter Meeting, Paper 79
Animal Production 44: 482-483 (1987)
ResumenThe effect of the level of energy intake (EI), crude protein concentration of the diet (CP), age and sex of growing lambs upon the retention of energy (ER) and nitrogen (NR) was studied. Milk diets based on cow's milk supplemented with either calcium caseinate or glucose and fat-filled skim milk were fed to 114 lambs of the Churra breed in a 3 x 3 x 2 x 2 factorial experiment using the comparative slaughter technique. The EI were 0.63, 1.05 and 1.46 MJ gross energy per kg M(0.75) per day. The CP were 179, 240 and 349 g/kg dry matter. Males and females between 2 and 16, and 16 and 30 days of age were used. The live-weight gain (LWG) and its energy and nitrogcn concentration were significantly influenced by the four factors studied and only the nitrogen content of the gain was independent of the sex of the lambs. The daily ER (MJ/day) and NR (g/day) were estimared from the LWG (kg/day) and the live weight (LW, kg) of the lambs according to the equations:
ER = -0.17 + 15.19 LWG - 16.32 LWG/LW - 219.57 (LWG/LW)2;
R = 0.965; residual s.d. = 0.24
NR = 0.38 + 31.42 LWG - 72.12 LWG/LW + 559.70 (LWG/LW)2;
R = 0.966; residual s.d. = 0.52
Since the El and the CP influence the ER and the NR it is impossible to estimate the ER (MJ/kgM(0.75) per day) and the NR (g/kg M(0.75) per day) from the intake of the metabolizable energy (MEI, MJ/kg M(0.75) per day) and nirrogen (NI, g/kg M(0.75) per day) according to the equations:
ER = -0.28 + 0.04 NI + 0.53 MEI; R = 0.938; residual s.d. = 0.07
NR = -0.35 + 0.23 NI + 0.79 MEI; R = 0.896; residual s.d. = 0.11
Combining the four equations it is possible to calculate the optimum energy/protein relationship of the diet. The values decrease with increasing LWG and ranged from 130 to 71 and from 155 to l26 kJ ME per g CP for the lambs of 2 to 16 and 16 to 30 days of age respectively.
DescripciónContributed to: 92nd Meeting of the British Society of Animal Production (Scarborough, UK, Mar 23–25, 1987).
Versión del editorhttp://www.bsas.org.uk/Meetings_&_Workshops/Past_Meetings/
Aparece en las colecciones: (IGM) Comunicaciones congresos
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