.A preliminary studywas made of chewing duringeatingwith a total of sixcows with rumen fistulas, given diets of hay or herbage. A sieving technique was used to determine the size of particles of food swallowed at intervals throughout the eating period. The number of jaw movements, number and weight of the swallowed food boluses and the time spent eating were measured with each diet. 2. The mean particle size of hay contained in a bolus collected at the cardia varied between individual cows from 1602 pm to 1244 pm. Boluses swallowed in the first few minutes of eating contained particles of a larger average size than those at any other time during the meal. Also, the rate of swallowing boluses of food was much faster at the beginning of a meal and the weight of boluses smaller than at any other time. The frequency of jaw movements did not vary appreciably during a meal. 3. Increasing the amount of hay given to the cows by 5 0 yo or giving a different hay did not cause any significarlt alteration in the average size of particles of swallowed hay, and changes in the rate of swallowing boluses, or in, the rate of jaw movements and the size of boluses were not very marked. 4. With a diet of herbage, boluses were swallowed rapidly and the average particle size of swallowed food was larger than that of hay. Also, there were slightly more jaw movements per min and larger boluses than with hay. 5 . The observations made in the study are discussed in relation to possible factors that determine the particle size of swallowed food.
The subcutaneous implantation of stilboestrol pellets in ewe and wether feeder lambs has been shown to result in a faster rate of gain in weight (Andrews, With from 12 to 36 mg stilboestrol the increase in the daily gain in weight ranged from 0.024 to 0.255 lb. Stilboestrol was usually given by one implantation; when a second implantation was made there was no significant additional increase in the rate of gain in weight.BeesonThe object of the present trial was to find the effect on the gain in weight of fattening lambs of a single subcutaneous implantation of 15 mg hexoestrol, another synthetic oestrogen closely related to stilboestrol. EXPERIMENTALTwo trials were conducted, one on privately owned farm flocks and the other on individually penned animals under carefully controlled conditions of environment and of feeding at the Rowett Research Institute. Farm trialA total of 524 lambs on six farms, around 8 months of age at the beginning, were studied. They were being fattened by methods representative of practice in north-east Scotland and, though the breeds differed from farm to farm, they were typical of those fattened in the area. Management varied slightly, but all lambs were run on grass and given turnips ad lib. supplemented with concentrates during the final stages of fattening. On each farm the lambs were randomly divided into two groups, control and treated. In each lamb of the treated group a 15 mg pellet of hexoestrol was implanted subcutaneously in the left ear. All lambs were weighed at the time of implantation and monthly thereafter. The lambs from five of the farms were slaughtered when considered by the farmers to be in fat condition; on the remaining farm they were sold for further feeding. Details of breed, sex and management of each flock are shown in Table I . The lambs were identified as groups on farms A, B and C by a paint mark and individually on farms D, E and F by a system of ear notching.https://www.cambridge.org/core/terms. https://doi
Two selenium (Se) supplementation trials were conducted in successive years involving a total of 70 red deer calves 3-15 months of age grazing pasture containing 30-57 ppb of Se on a dry matter basis. The trials compared growth rate, whole blood Se and glutathione peroxidase (GSHpx) concentrations of calves which received periodic doses of oral Se or a single injection of barium selenate (equivalent to 50 mg Se) or no Se supplementation. There were no significant weight gain differences between treated and untreated groups in either trial. Whole blood GSHpx levels were strongly correlated with blood Se levels (r = 0.9278) and produced the following regression equation: GSHpx = 0.0155 Se - 2.292. In both years the 3 month old calves had GSHpx levels of 6-9 kU/I which probably derived from maternal transfer of Se. The GSHpx levels in unsupplemented calves declined from these levels to a minimum in winter (group means approximately 2.6) and then progressively rose the following spring and summer. Periodical oral dosing with Se or a single injection of barium selenate significantly elevated blood Se and GSHpx levels throughout the trials.
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