Blood chemistry, nutrition, productivity and fertility were monitored and their interrelationship examined in groups of cows from 15 commercial dairy herds. Plasma urea, albumin, glucose, non-esterified fatty acids (NEFA), acetone, calcium, magnesium, inorganic phosphorus (IP), blood copper, haemoglobin and packed cell volume were examined in relation to the intakes of starch equivalent (SE) digestible crude protein (DCP), calcium, phosphorus, magnesium, sodium, potassium, copper and manganese. The most consistent correlations were found for the regressions of SE intake as a percentage of requirements (I/R per cent) on plasma non-esterified fatty acids, the ratio of SE intake over DCP intake on plasma urea, DCP I/R per cent on plasma urea and phosphorus I/R per cent on plasma IP, but factors other than nutrition accounted for a large part of the variation in all cases. The mean plasma glucose concentration within +/- three days before or after first service of cows which held was higher than that of cows which returned, but the difference was only approaching significance at the 5% level and it is doubtful whether it could be of practical value. No other differences in blood component levels were demonstrated for first or second service. It is concluded that, within the nutritional ranges encountered, the levels of the selected blood components did not show a consistent relationship to nutrient balance or potential fertility. In this context a multiple analytical scheme employing these components would appear to be of limited value, particularly if samples are taken on only one occasion. The technique is more appropriately regarded as an aid to the conventional approach involving the examination of feeding systems and feedstuffs, herd records, management and clinical conditions.

Coccidiosis occurs sporadically in lambs at about 6 weeks of age when oocyst output is very high in healthy as well as in diseased lambs. These experiments were designed to throw light on the source of infection and to correlate oocyst output in lambs and ewes with performance in lambs. In two experiments, one indoors on deep litter the other in outdoor paddocks, oocyst output (of different coccidial species), body weight and clinical state of lambs were recorded weekly. Oocyst output in ewes was also recorded, starting 1-4 weeks before lambing. Monensin was included in the concentrates of ewes and/or lambs, up to lambing or before and after lambing. No periparturient rise was detected in the oocyst output of ewes. Monensin drastically reduced oocyst output in animals receiving it. Oocyst output in lambs appeared to be little affected by the output of ewes around the lambing period, but was reduced if the ewes' output was kept low after lambing. Lambs receiving monensin tended to produce drier faeces but their weight gain was not significantly greater than that of controls. Eimeria crandallis was the predominant species in the lambs, followed by E. ovinoidalis and E. ovina.

Three inactivated porcine parvovirus vaccines were tested for efficacy in 66 susceptible gilts. The gilts were challenged with virulent virus on the 40th day of gestation. All the vaccines provided excellent protection against fetal mortality despite insignificant serological responses to one of them. Good protection was obtained with two of the vaccines even when the dose was substantially reduced. Unvaccinated controls had very few viable fetuses.

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