The effect of post-ruminal infusion of protein or energy on the pathophysiology of Trichostrongylus colubriformis infection and body composition in lambs was investigated using the comparative slaughter technique. Of 52 Dorset DownxCoopworth wether lambs (mean body weight 30.5, s.e. 0.44 kg), 8 comprised an initial slaughter group (IC), 36 were infected daily, per os, with 3000 Trichostrongylus colubriformis larvae per animal, and the remainder (C) were parasite-free controls. Groups of 12 infected animals were given either a continuous infusion (via abomasal catheter) of 50.4 g/day crude protein as sodium caseinate (PI), glucose (EI) in isocaloric amounts to PI, or a solution containing P and Na at the same rate as the caseinate infusions (SI). Uninfected controls (C) were also infused with this solution. Animals were slaughtered after 6 and 12 weeks for estimation of worm count and body composition. All animals were offered, ad libitum, meadow hay (118 g crude protein/kg dry matter (DM); 930 g organic matter/kg DM; 0.65 organic matter digestibility). DM intake of infected animals decreased by approximately 22% in PI and EI and by 32% in SI animals. Mean total metabolizable energy (ME) intake during the experiment (inclusive of infusions) was C, 0.607; PI, 0.687; EI, 0.704; SI, 0.617, s.e.d. 0.0308 MJME (kg W)-0.75 day-1. Nitrogen retention in infected sheep was increased fourfold by protein infusion and twofold by energy infusion. The rate of energy retention was reduced by infection, increased by protein infusion but only partly by energy infusion. Protein infusion reduced mean faecal egg output and mean total parasite count. Increased endogenous plasma loss into the gastrointestinal tract was similar in all infected groups. It was concluded that a major limiting factor in efficient food utilization in animals with gastrointestinal nematode infections is a parasite-induced protein rather than energy deficiency, possibly the result of increased endogenous protein losses into the gastrointestinal tract. The debilitating effect of internal parasites could be markedly reduced by increasing duodenal protein supply.

No abstract

No abstract

No abstract

Closely shorn Scottish Blackface female sheep aged 9–14 months, half on high plane and half on low plane nutrition, were subjected, in climate chambers, to two short acute cold exposures down to – 20° C. The exposures were separated by a period of two weeks in either a thermoneutral environment ( + 30° C.) or a subcritical environment ( + 8° C.). Thirty-seven out of 40 sheep showed a greater resistance to body cooling at the second exposure. The mean rates of fall of rectal temperature (in° C. per 100 min. exposure) were 0·42 at the first exposure and 0·22 at the second exposure. One group of sheep showed virtually complete resistance to cooling at second exposure under the specific test conditions used. The highly significant increase in cooling resistance was taken as a measure of acclimatisation.The main conclusions were as follows:1. Blackface sheep could acclimatise to cold as a result of one acute exposure to cold lasting about 8 hours.2. Acclimatisation was slightly greater amongst sheep kept at a subcritical temperature (+8° C.) between acute exposures.3. Additional data suggested that some acclimatisation resulted from 2 weeks prior exposure to +8° C. alone; but none was induced by 2 weeks prior habituation to the climate chamber environment at + 30° C.4. Sheep on high plane nutrition showed greater initial cold resistance and slightly greater ability to acclimatise than those on low plane nutrition.5. Cold resistance was more closely related to recent weight gain than to absolute body weight.6. There was great individual variation in initial cold resistance and in ability to acclimatise.7. Sheep kept at + 8° C. between acute cold exposures maintained significantly lower rectal temperatures than those kept at +30° C.