The nutrition of the veal calf. 2. The effect of different levels of protein and fat in milk substitute diets.

摘要: 1. Seventy-two bull calves, comprising forty-eight Ayrshire and twelve each of the Friesian Jersey breeds, were used in a randomized block experiment. They reared from birth on liquid diets, offered two feeds daily, at either restricted or ad lib. levels. The level feeding was such that sufficient diet fed to allow for weight gain I kg/d, calves given this slaughtered 77 kg above mean breed. diets 22 % mature cow breed.2. Three milk substitutes, based spray-dried skim-milk powder, whey powder margarine fat, compared. Two these high-protein (26–29 protein) designed contain 20 fat (LFHP) 30 yo (HFHP) other low-protein (19 (HFLP).3. Age slaughter lowest HFHP highest HFLP. Total dry-matter intake did not differ between treatments, but daily lower Relative LFHP much greater than After adjustment differences treatments intake, relative tended be HFHP. No difference occurred incidence diarrhoea high rectal temperature (> 39.33°). However, higher those HFLP diet.4. Digestibility nitrogen calcium balance trials made six replications 4 10 weeks age. Dry-matter age diets. Apparent digestibility diet. True protein significantly treatments. lactose diet.5. (LFHP HFHP) N Ca retention, retention by (HFLP) markedly lower. Daily faecal excretion unaffected treatment, urinary biological value LFHP, with corresponding values being intermediate two. reten tion/100 g HFLP, weeks, Metabolic endogenous estimated as 0.192 g/100 192.9 mg/kg0.72 live respectively.6. Haematological findings showed high-fat (HFHP HFLP) resulted slower rate decline packed cell volume haemoglobin content low increase percentage lymphocytes. Diet eosinophils compared marked rise treatments.7. Carcass perirenal deposition (HFLP HFHP).8. It is concluded dietary readily available source energy increasing large quantities products added fat. Unless additional carcass required, no advantages