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Title: The control of food intake by the dairy cow in relation to body conditions at calving and subsequent performance
Author: Garnsworthy, Philip Charles
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1980
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Two trials were performed in consecutive years to investigate the effect of body condition at calving on food intake, milk yield, and changes in bodyweight and condition score after calving. The experimental design was the same for each trial, the second trial being used to support and extend the results of the first. Twenty-four autumn-calving dairy cows were used in each trial. The breeds involved were Friesian, Friesian cross Ayrshire and Ayrshire. Eight cows were allocated to each of three treatment groups which were matched according to previous lactation yield, breed and parity. The cows were housed from two months before expected calving date and individually fed on hay, malt distillers grains, barley and straw, to achieve three groups of cows with different body conditions at calving. The conditions ranged from 1 to 2 (low), 2 to 3 (medium), 3 to 4 (high). For 16 weeks after calving, all cows were individually fed to appetite on a complete diet composed of silage, malt distillers grains, barley, swedes and soya bean meal. In the first trial, significant differences were found between groups in the mean daily intake of dry matter during the first 16 weeks of lactation. In the second trial, greater differences were achieved between groups in average condition score at calving. A diet of slightly higher energy concentration was fed after calving. The effect of condition score at calving on dry matter intake was greater than in the first trial and clearer differences were found between groups. The conclusions drawn from these trials are: 1. Cows in poorer condition at calving were in positive energy balance sooner than fatter cows because they were able to increase their food intake at a faster rate. 2. Thinner cows produced more milk directly from food rather than via body fat and were therefore biologically more efficient. 3. There appears to be no benefit from fattening cows during the dry period if high-energy complete diets can be fed in early lactation. 4. Further research is needed on the effect of body condition at calving using cows studied over complete and more than one lactation, and when different diets are fed. A series of experiments were performed to investigate the use of chromic oxide for estimating feed intake by dairy cows fed in groups on complete diets. Chromic oxide was administered in pellets based on ground straw, barley and molasses. Preliminary experiments showed that sheep and beef cows exhibited significant diurnal variation in the excretion of chromic oxide when given these pellets twice daily. Using this knowledge, an experiment was designed to measure individual food intake by dairy cows fed on complete diets. Five cows in early lactation, fed on a high energy diet, and five cows in late lactation, fed on a low energy diet, were used Chromic oxide pellets were given at the morning and afternoon milkings; faecal samples were taken before or after each milking for seven days. Average intake of dry matter was calculated for each cow using the digestibility values obtained for the diets' in a trial with sheep. Calculated intakes agreed more closely with predicted intakes for cows in the early lactation group. It was concluded that the use of chromic oxide to estimate the food intake of group-fed cows on the complete diet system gave acceptable results.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available