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Two separate experiments were carried out to establish the effects of the protein:energy ratio in milk replacers on growth performance, plasma lipid concentrations and fatty acid composition in adipose tissue of male goat kids. In the first experiment there were 211 3-day- old goat kids and in the second experiment there were 121 kids aged 3-7 days. The animals were fed ad libitum for a period of 4 weeks on milk replacers containing either 11.5 or 9.5 g crude protein/MJ metabolizable energy. In essence, protein was exchanged with fat on a weight basis. Milk concentrations were increased from 160 to 190 g/l in experiment 1, from 150 to 180 g/l in experiment 2. There were significant increases in body weight and feed intake when the milk replacer with high protein : energy ratio was fed. Group mean average daily weight gain was 168 and 203 g for the groups with low and high dietary protein:energy ratio in experiment 1; for experiment 2 the values were 139 and 160 g. Average dry matter intake was 18 and 14% higher for the diet with high protein:energy ratio in experiments 1 and 2, respectively. There was no change in either feed conversion (feed:gain ratio) or energy conversion (weight gain:energy intake ratio). There were no consistent diet effects on plasma lipid concentrations. Dietary fatty acid composition was reflected by that of adipose tissue. The milk replacer with high protein:energy ratio produced a small increase in the contents of myristic and palmitic acid in adipose tissue.

Twenty, 1-2-day-old goat kids were used in a feeding trial to investigate the effect of linoleic acid (LA) (C18:2n-6) intake on weight gain and carcass composition. Eight animals were selected randomly and killed at the start of the trial to determine initial body composition. The other animals were assigned to the three dietary treatments and were fed milk replacers with varying LA concentrations (low: 5.5%; medium: 11.2% and high: 17.1% LA of total fatty acids) for 5 weeks. There was no systematic effect of LA intake on body composition. The average retentions of fat, protein, ash and energy were 46.3%, 61.2%, 42.2% and 37.4% respectively. Increased intakes of LA caused a significant increase in LA content of the carcass and of the weight gain, whereas there was a simultaneous decrease in fatty acids with 16 carbon atoms or less. The incorporation of LA into carcass was directly related to intake, but the percentage retention of LA remained constant. The data indicate that in goat kids the intake of extra LA raises the amount of LA in carcass but does not affect the total fat content.

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