The effect of early-weaning rations upon the efficiency of growth and carcass production with some observations on the development of forestomachs in calves

The live-weight gain, efficiency of food conversion, energy and nitrogen accretion as edible carcass, and the forestomach development were measured in three groups of calves fed for 10 weeks (days 19-89 of life) either a diet of 4-5 1 of milk daily, or a concentrate meal containing 4% sodium propionate ad libitum, or a concentrate meal ad libitum. All groups had access to lucerne chaff and water ad libitum. The mean live-weight gains of the three groups of calves were 47-5, 36'6 and 37-1 kg respectively even though their total energy and nitrogen intakes were not significantly different. The provision of dietary propionate did not improve the efficiency of food conversion or of energy or nitrogen accretion as the calves ate less of the meal containing propionate and more lucerne chaff. The differences in live-weight gain could be accounted for by the differences in carcass weight. Associated with the higher live-weight gain was a much higher efficiency of food utilization and of edible carcass energy and nitrogen accretion. The superior efficiency of the unweaned calves was concluded to be due to the liquid portion of the diet by-passing the rumeno-reticulum into the abomasum where the efficiency of utilization of highly digestible protein and carbohydrate is greater. The concentrate plus propionate fed calves ate less concentrate but more chaff and had a lower efficiency of food utilization and edible carcass energy accretion than the other weaned group of calves. The weight of rumeno-reticular tissues was greater in the weaned than in the unwearied calves, although the meal plus propionate group ate similar quantities of chaff to the unweaned group. In all groups, the degree of papillary development was related to the intake of concentrates plus roughage. The most appropriate manner to describe ruminal tissue weight is discussed

Phosphorus metabolism in ruminants. 2. Effects of inorganic phosphorus concentration upon food intake and digestibility

Four sheep, prepared with bilateral re-entrant parotid duct catheters, ruminal fistulas and abomasal catheters, were offered a pelleted high-calcium low-phosphorus diet. By infusing saline or phosphate solutions into the abomasum with or without diversion of the parotid saliva, three treatments were created: low ruminal, low blood; high ruminal, high blood; and low ruminal, high blood inorganic phosphorus concentrations. The organic matter intake of the sheep on the low-blood treatment was 34% less than on either of the high-blood treatments. Although there were no differences between treatments in organic matter digestibility, the digestibility of the neutral-detergent fibre fraction on both low-ruminal treatments was 5% lower than on the high-ruminal treatment. There were no differences between treatments in ruminal fluid volume, but there was a tendency for the retention times of ruminal fluid and caeco-colic digesta to be greater and the rate of flow of fluid from the rumen and daily parotid saliva secretion to be lower when less food was eaten. It is concluded that although phosphorus deficiency may depress microbial digestion, the reduced food intake of the sheep was not due to a depression in microbial digestion and that the primary factor limiting food intake was due to some nondigestive tract disturbance, possibly a disturbance of intracellular metabolism

A note on the voluntary food consumption and the sodium-potassium ratio of sheep after shearing

The daily voluntary food consumption (VFC), water intake and urinary excretion of water, sodium and potassium of eight sheep were studied before and after shearing. The extracellular volume of each sheep was measured twice before and three times after shearing. VFC was significantly higher for the first 3 weeks after shearing than for the 3 weeks immediately before shearing. There was a decreased excretion of Na in the urine and a smaller Na/K ratio for the first 2 weeks after shearing, although the extracellular volume was not significantly increased until 4 weeks after shearing. Within, but not between, the 3-week periods before and after shearing, there was a close linear relationship between VFC and water intake, the latter being significantly less for the same VFC after shearing. During weeks 4 and 5 after shearing, there was an increased loss of Na in the urine and a higher Na/K ratio, and the linear relationship between VFC and water intake was intermediate between that shown before and after shearing. The VFC of the sheep before shearing and in week 5 after shearing were similar

An improved technique for plant protein extraction

Studies on the extractability of plant protein showed that solubilisation of protein from plants harvested at different stages of growth before flowering depended on the water content of the macerated plant material and the level of alkalinity. Solubilisation increased as the pH value was raised from 6.2 to 11.00 by addition of NaOH solution and as the dry matter content decreased from 90 to 37.5 g/kg of mixture by water dilution. A dry matter concentration of 45 g/kg and pH 11 were adopted as most suitable extraction conditions which allowed 82‐86% nitrogen yield from the five plant species tested. Ageing of plants had an adverse effect on nitrogen extractability. Of the total extractable nitrogen, the true protein nitrogen content increased with age up to commencement of flowering but once flowering had commenced the content was lower

Effects of dietary phosphorus and nitrogen deficiencies on the intake, growth and metabolism of lambs

The effects of dietary deficiencies of phosphorus (P) and nitrogen (N) were studied in 28 lambs allotted to seven treatments for 18 weeks. The lambs in four treatments were offered roughage-based diets ad libitum containing high (H) or low (L) levels of P (4.13 or 0.98 g/kg dry matter (DM)) and N (108 or 68 g crude protein/kg DM). The lambs in the remaining three treatments were fed the same quantities of DM of the HNHP diet as the lambs receiving the three deficient diets (HNLP, LNHP and LNLP). A dietary deficiency of P caused a reduced DM intake and liveweight gain, lower yields of N and DM in carcass muscle and reduced DM, N and P contents of bone. A dietary deficiency of N resulted in reductions in DM intake, liveweight gain, DM digestibility, N balance, and in carcass muscle and bone DM and N. The deficiencies of N and P were not additive in lowering food intake but were additive in reducing the mineralization of the bones. The DM F intake of the lambs offered their diets ad libitum was closely correlated to the log of the plasma inorganic P and urea N concentrations (R = 0.72). Feeding lambs with restricted quantities of diet HNHP resulted in higher liveweight gains and DM and N digestibilities than when any of the deficient diets were offered. Measurement of the N content of the lambs by a neutron capture gamma ray analysis technique showed that the changes were occurring progressively over the experimental period. The P content of the metatarsal bone, measured by a neutron activation technique, showed progressive changes. Although the faecal endogenous losses of P were related to P intake, high urinary losses were observed in those lambs which had their food intake limited by low dietary N alone, or had their food intakes restricted. The total endogenous P losses of the lambs were most closely dependent upon the DM intake and plasma inorganic P together. The efficiency of P absorption was high (> 0.75) in all lambs except for those given the HNHP diet ad libitum. The glucose entry rate was reduced in the lambs offered diets deficient in either N or P. Mechanisms by which the N and P deficiencies reduce DM intake are discussed