Search

Two experiments are reported in which 119 steers were fed ad lib. on maize silage, supplemented with different proportions of dried lucerne. In addition, the effect of including white fishmeal with the silage at levels up to 13% of the total diet was studied in one experiment. In another, the effect of adding urea to the silage (at 0.9% of the DM) was investigated. In both experiments the response in liveweight gain to increasing amounts of lucerne was curvilinear. The highest mean level of daily gain (1.5 kg/head per day) in the first experiment was achieved when the diet contained 62% lucerne or 13% fishmeal. In the second experiment the highest mean daily gain (1.1 kg/head per day) was achieved when the diet contained 71% lucerne. Daily liveweight gains were similar for the cattle fed 25% of the diet as lucerne with silage to which urea had been added, and for those fed higher proportions of lucerne with untreated silage. [ABSTRACT FROM AUTHOR]

Two studies are described in which the behaviour of 24 seven-month-old Friesian steer calves was observed. The first study (G1) was undertaken at the time of turnout to pasture, and the second (G2) 5 days later. The calves appeared to adapt rapidly to the change in environment, though in study G1 grazing was frequently interrupted. In study G2 the calves showed normal behaviour patterns and spent a total of 4.25 hours grazing. There was a positive correlation between age and weight at turnout and time spent grazing in study G1. However, this relationship was not apparent in G2, and there was no relationship between time spent grazing in G1 and G2. Mean weight loss upon turnout was 7.44% of liveweight, in spite of the feeding of hay and barley at grass. There was no relationship between weight at turnout and subsequent weight loss. The results confirmed other experimental findings which suggest that weight loss at turnout is largely a reflection of changes in the weight of alimentary tract contents, rather than an inability to adapt to the change in environment. The calves were grazed at two intensities (‘low’ and ‘standard’) during the grazing season. Growth rate in winter and weight at turnout were negatively correlated with growth rate in the first month of the grazing season. This relationship was more apparent in the ‘low’ intensity group which received a liberal daily herbage allowance at this stage of the season. Partial correlation analysis, in which pre-grazing growth rate was held constant, indicated that weight and age had little independent influence on growth rate at grass, though there was a positive relationship between weight for age at turnout and gain during the grazing season. The importance of a target weight at turnout is discussed in relation to the 18-month beef production system. It is concluded that younger, lighter, cattle at turnout may not be at a disadvantage when adequate amounts of herbage are on offer early in the grazing season. [ABSTRACT FROM AUTHOR]

Six calves, six heifers and six dry cows grazed a mature sward (treatments A and B) and a leafy aftermath (treatment C) in succession. The yields of herbage on the two swards were 7100 lb and 1950 lb DM per acre (7950 kg and 2180 kg per ha), respectively. The amounts of herbage offered daily were 47 lb (21.5 kg) DM per head (treatment A), 70 lb (32 kg) (treatment B), and 60 lb (27 kg) (treatment C). Two estimates of herbage organic-matter intake (O.M.I.) were made on each treatment; records of grazing behaviour were made on treatments B and C. The digestibility of the diet selected on treatment C was higher than that selected on treatments A and B, and the animals ate significantly more O.M. on treatment C. The total grazing times on treatments B and C were similar, but the animals found it more difficult to graze on treatment B. Herbage O.M.I, increased significantly from treatment A to treatment B, even though the quantity of herbage offered per day on treatment A greatly exceeded the amount eaten. The increase in O.M.I, was found to be associated with an increase in faecal O.M. output, but the digestibility of the diet did not change. [ABSTRACT FROM AUTHOR]

The absence of an N-terminal amino acid with a free alpha-amino group from the heavy chain of rabbit immunoglobulin IgG has been confirmed and no evidence could be found of a blocking formyl, acetyl or propionyl group. The N-terminal amino acid appears to be pyrrolid-2-one-5-carboxylic acid (PCA) in all molecules. A mixed amino acid sequence follows in the approximate proportions: PCA-Ser-Val-Glu-Glu-Ser-Gly-Gly-Arg, 50%; PCA-Ser-Leu-Glu, 20%; PCA-Glu(NH(2)), 20%. The heavy chains of a purified antibody, namely anti-(human serum albumin), and of immunoglobulin IgG from a rabbit homozygous at the allotypic loci both showed a similar mixed N-terminal sequence.

1. Sperm-whale apomyoglobin was digested with chymotrypsin in a dialysis sac. The ultrafiltrate contained incompletely hydrolysed fragments which partially inhibited the precipitation of metmyoglobin and apomyoglobin by some antisera produced against metmyoglobin. The inhibitory activity was stable to heating at 100 degrees and depended on the peptide structure. 2. The fragments were fractionated according to molecular size and were purified by ion-exchange chromatography. Six pure peptides and two peptides which contained a minor impurity were isolated. Their amino acid compositions and N-terminal amino acid sequences were determined and their entire amino acid sequences deduced from the known amino acid sequence of sperm-whale myoglobin. 3. The peptides formed no detectable precipitates with the antisera. Five of the eight peptides partially inhibited the precipitation of apomyoglobin and/or metmyoglobin by one antiserum. Six of the peptides inhibited the precipitation of apomyoglobin by one or other of two antisera; at least two of these peptides inhibited both antisera. One peptide failed to inhibit the precipitation of either antigen by either antiserum. Two of the peptides possessed the same serological specificity. 4. The molar ratios of inhibitors to antigen for 50% of the maximum inhibition decreased as the molecular size of the inhibitor increased. With one antiserum and with apomyoglobin as the antigen, molar ratios 12 and 80 were obtained for peptides with molecular weights 2051 and 793 respectively. 5. The size and structure of an antigenic site is discussed in relation to the known steric configuration of myoglobin.