Castrated Male Cattle Research Articles

Growth and hormonal response of intact and castrate male cattle to trenbolone acetate and estradiol.

Effects of castration and anabolic implants on weight gain, rib soft tissue composition and serum hormones were studied in cattle using a completely random design with a 2 x 2 factorial arrangement. Half of 16 bulls and 16 steers (Angus or Angus x Brahman) aged 9 mo and weighing 290 kg were treated with an implant (200 mg trenbolone acetate and 24 mg estradiol). Half of each group were not treated with an implant. A growing diet was fed for 95 d and half the animals in each group were slaughtered. Animals in the treated groups were reimplanted with trenbolone acetate and fed a finishing diet for 84 d and slaughtered. Percentage dry matter, fat and protein were determined on soft tissue from the 9-10-11th rib. Two blood samples were collected from each animal every 2 wk. Serum was assayed for five hormones. During the growing phase, untreated and treated bulls and treated steers gained more weight and had leaner rib sections that untreated steers (P less than .05); after the finishing phase, there were no differences among groups. Untreated steers had lower insulin-like growth factor (IGF-I) and higher cortisol concentrations during both phases of growth than untreated bulls did (P less than .05). Treatment with implants increased IGF-I concentrations in steers during both phases and reduced cortisol during the finishing phase.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of silage-based and dried forage-based diets for finishing beef cattle

AbstractTwo experiments have been carried out to compare silage-based and dried forage-based diets for finishing beef cattle, and to examine the effect of supplementing the silage-based diet with additional protein. The three diets used in experiment 1 consisted of (1) grass silage supplemented with a low-protein, cereal-based concentrate (98 g crude protein (CP) per kg dry matter (DM)) (2) grass silage supplemented with a high-protein, cereal/soya-bean meal concentrate (208 g CP per kg DM) and (3) grass hay supplemented with a cereal-based concentrate (130 g CP per kg DM). The two diets used in experiment 2 consisted of (1) grass silage supplemented with barley and (2) a mixture of grass hay and artificially dried grass supplemented with barley. All the diets contained approximately 700 g forage and 300 g concentrates per kg DM except diet 3 in experiment 1 which contained 240 g hay and 760 g concentrates per kg. The silages were of high digestibility (digestible organic matter in dry matter 0·72) and were well preserved (ammonia N 36 g/kg total N). The diets were offered to castrated male cattle which were initially 384 kg in experiment 1 and 515 kg in experiment 2. For diets 1 to 3 in experiment 1 and diets 1 and 2 in experiment 2 respectively metabolizable energy intakes were, 92, 94, 94, 124 and 120 MJ/day; live-weight gains were 1·21, 1·16 and 1·21 (s.e. 0·044) and 1·25 and 1·22 (s.e. 0·060) kg/day; carcass gains were 0·76, 0·76 and 0·75 (s.e. 0·034) and 0·80 and 0·74 (s.e. 0·036) kg/day; carcass fat classifications (five-point scale; 1 = leanest, 5 = fattest) were 2·4, 2·9 and 2·2 (s.e. 0·09) and 3·6 and 3·6 (s.e. 0·18); mean subcutaneous fat depths were 6·8, 8·1 and 6·6 (s.e. 0·74) and 7·8 and 7·4 (s.e. 0·48) mm; areas of m. longissimus dorsi at the 10th rib were 66·4, 69·4 and 71·3 (s.e. 3·16) and 77·6 and 72·3 (s.e. 1·52) cm2 and marbling scores (eight-point scale; 1 = leanest, 8 = fattest) for m. longissimus were 1·7, 2·5 and 2·2 (s.e. 0·24) and 3·2 and 2·8 (s.e. 0·16). It is concluded that performance, efficiency of energy utilization and carcass fatness were similar for silage-based and dried forage-based diets, and that protein supplementation of a silage-based diet did not affect performance but tended to increase carcass fatness.

Effect of zeranol implantation and dietary protein level on growth and blood hormones and metabolites of bulls

Recent reports have suggested that growth in entire male cattle (bulls) may be increased by implantation with the growth promoter zeranol. It is well known that given similar nutrition bulls grow faster than castrate male cattle (steers). This effect may be attributed to the presence of testicular steroids in bulls which stimulate lean tissue deposition and hence greater live-weight gain. A major objective of this study was to provide further information on the effects of zeranol implantation on growth and blood concentrations of endogenous hormones and metabolites. Effects on concentrations of the endogenous steroids, testosterone and oestradiol-17β were of particular interest.

Effects of some anabolic agents on the growth, carcass and tissue composition of barley-fed entire and castrated male Friesian cattle

ABSTRACTThirty-eight barley-fed entire and castrated male Friesian calves were used to examine the effects of different implanted anabolic agents on growth and carcass and tissue composition. Entire males were implanted with trenbolone acetate plus hexoestrol alone or following an earlier implantation of zeranol, or with zeranol alone. Control bulls (no implant) and steers treated with trenbolone, acetate plus hexoestrol were also studied. The anabolic agents tended to increase growth rate in bulls, and caused an increase in fat deposition. Treated steers had more abdominal fat than all bulls, but did not have more carcass fat. However, the carcasses contained less saleable meat and had a lower retail value because of lower lean-to-bone ratio. There were no significant differences between any of the groups in the proportions of lipid and water in the lean tissue. Transporting the bulls resulted in a high pH and a dark colour in m. tongissimus. The results suggest that anabolic agents have small biological effects which directly modify the quantitative and qualitative meat production characteristics of bulls.

Fat deposition in Hereford and Friesian steers: 1. Body composition and partitioning of fat between depots

SUMMARYIn this paper, the first of a series of three in which fat deposition is examined in 42 castrate male Hereford and Friesian cattle, details are given on the experimental material and procedures used in all papers. Whole body composition (anatomical and chemical) and the partitioning of fat within the body are also reported in this paper.Four, two and 15 animals were slaughtered at 6, 13 and 20 months of age, respectively, afterad libitumfeeding of a complete pelleted diet.The Friesians were heavier than the Herefords, having 10%, 20% and 14% heavier empty bodies at 6, 13 and 20 months, respectively.At the same age, the Friesians had a greater percentage of empty-body weight as carcass muscle, carcass bone, total body water and total body ash than the Herefords but a lower percentage as dissectible fat and total body lipid. An analysis of linear body measurements showed no difference between breeds in the stage of development of external body dimensions at 20 months of age, and it was concluded that at the same age and stage of development of live weight or size, the Friesians were leaner than the Herefords.Relative growth coefficients of the fat depots showed late developmental growth in some intra-abdominal depots (omental and perirenal–retroperitoneal) but not in another (mesenteric). Relative growth coefficients of the omental, mesenterie and intermuscular depots were different between breeds. The Herefords deposited more dissectible fat subcutaneously than the Friesians whereas the Friesians deposited more in the intraabdominal depots. A multivariate index of fat partitioning, which was not influenced by age or stage of development of the fat depots, was not significantly correlated with fatness, suggesting no direct link between the pattern of fat partitioning and body-fat content.Breed differences in the distribution of fat within the subcutaneous and intermuscular depots were minor compared with the large difference in the partitioning of fat between depots. It was thus concluded that the factors controlling fat partitioning do not influence the distribution of fat within depots.

Effects of trenbolone acetate and resorcylic acid lactone on protein metabolism and growth in steers

ABSTRACTTwenty-four castrate male cattle were used in two nutritional balance and slaughter experiments to measure the effects of two implantations with 300 mg trenbolone acetate and 36 mg resorcylic acid lactone over the live-weight range 250 to 400 kg. Control and implanted animals were pair-fed barley-based diets of differing protein concentration in the first experiment and the lower protein diet at two levels of feeding in the second experiment.Daily live-weight gain and nitrogen retention were significantly increased by implantation in both experiments. The carcasses of implanted animals contained significantly more lean meat and a higher proportion of meat in the forequarter. The edible portion of these carcasses contained significantly more protein and water and less fat.Live-weight gain and carcass composition were not influenced by dietary protein intake. Increased feeding level improved live-weight gain, suggesting that a higher metabolizable energy intake would give an increased response to implantation.

Effect of estradiol and progesterone on lymphocyte and neutrophil functions in steers.

Polymorphonuclear leukocyte function and lymphocyte blastogenesis in response to mitogens were evaluated in castrated male cattle after the repeated administration of estradiol or progesterone. Polymorphonuclear leukocyte function was evaluated with the following five parameters: (i) random migration under agarose, (ii) ingestion of 125I-labeled Staphylococcus aureus, (iii) nitroblue tetrazolium reduction, (iv) iodination, and (v) antibody-dependent cell-mediated cytotoxicity. The administration of high dosages of estradiol cypionate produced no measurable effect on the total or differential leukocyte count, neutrophil function, lymphocyte blastogenesis, or blood cortisol levels. The administration of high dosages of progesterone caused a significant enhancement of random migration by neutrophils and a depression of the activity of the myeloperoxidase-H2O2-halide antibacterial system (iodination) of the neutrophil. Progesterone administration did not cause a measurable effect on the lymphocyte blastogenic response to mitogens or the ability of polymorphonuclear leukocytes to ingest S. aureus, reduce nitroblue tetrazolium, or mediate antibody-dependent cell-mediated cytotoxicity. Progesterone did not cause a change in blood cortisol concentrations; therefore, the observed effects on polymorphonuclear leukocyte function were not due to alterations in blood cortisol concentrations. Impairment of the iodination reaction indicates that high dosages of progesterone interfere with an important bactericidal mechanism of the neutrophil.

The relative efficiency of food utilization of British Friesian entire male and castrate male cattle at two levels of feeding

ABSTRACTA combined nutritional balance and comparative slaughter experiment using 20 animals compared entire male and castrate male cattle when pair-fed at high and medium levels of feeding and slaughtered at a constant 400 kg live weight. The carcasses were dissected into lean meat, separable fat, and bone, and the edible portion of the carcass was further analysed for crude protein, fat and water.There were no significant differences between entire and castrate animals in their ability to digest energy, nitrogen or modified acid detergent fibre. The mean metabolizable energy values (MJ/kg dry matter) of the diets were 10·6 for castrates and 10·9 for entire animals. Live-weight and carcass gains (kg/day) for each treatment were respectively: entire high feeding level, 1·10, 0·69; entire medium feeding level, 0·91, 0·57; castrate high feeding level, 0·92, 0·57; castrate medium feeding level, 0·79, 0·48. Castrate carcasses contained significantly (P < 005) less lean meat and more separable fat. The edible portion of these carcasses also contained significantly (P < 0·05) more total fat but less protein and water than entire carcasses. Daily carcass protein gain was significantly higher for entire animals (P < 0·001) but daily energy gain was not significantly different. The most efficient conversion of dietary metabolizable energy and crude protein to either live weight or carcass meat production was obtained by the use of entire animals and the high level of feeding.

Effects of variations in energy and protein intake on digestibility, nitrogen balance and carcass composition in British Friesian castrate male cattle

AbstractTwenty-seven castrate male cattle were used in two nutritional balance and slaughter experiments to measure the effects of increasing levels of dietary protein (9 to 15% in the dry matter) at two levels of feeding (approximately 16 and 22 MJ metabolizable energy (ME)/100 kg live weight (LW) per day) on digestibility, nitrogen (N) balance and carcass growth and composition over the LW range 130 to 390 kg.The higher level of feeding increased LW gain and carcass gain (CG) but higher protein intake increased LW gain and CG only at the higher feeding level as a result of its favourable effect on digestibility. N balance tended to overestimate carcass N retention at higher levels of protein intake.The higher level of feeding increased the separable fat and total fat in the carcass. Increased protein intake had no effect on the lean meat content but increased the percentage protein in the edible portion of the carcass. LW gain, CG and carcass energy deposition were related to ME intake only but N balance and carcass protein gain were related to both ME and digestible crude protein intake.

Prediction of the energy requirements for growth in beef cattle. 2. Hereford × British Friesian steers given dried grass or barley

SUMMARY1. Hereford × British Friesian castrate male cattle, growing from about 80 to 500 kg, were given equal amounts of metabolizable energy (ME) from dried grass pellets or from a pelleted diet of barley and a protein supplement. Two animals on each diet were fed close to appetite (High) and two at a level mid-way between maintenance and appetite (Medium). The rations for all animals were reduced to approximately maintenance for 4 weeks on three occasions equally spaced throughout the experiment. Measurements of energy and nitrogen balance were made for each animal at intervals of 6 to 8 weeks. Total body-water content was estimated from D20 dilution at intervals of 110 kg live weight.2. Values for the metabolizability of the gross energy of the dried grass and barley/protein diets were 0·55 and 0·67.3. Metabolic heat production during growth was closely related to body weight to the power 0·75. Predicted basal metabolism was 395 kJ/kg 0·75 per 24 hr.4. Estimates of the net efficiency of utilization of ME for growth were unaffected by small variations in the exponent of W used to describe the effect of body size on heat production. Both diets were utilized above maintenance with a net efficiency close to 0·62.5. Nitrogen balance trials seriously overestimated nitrogen retention. Gains in fat-free body mass estimated from D2O dilution were combined with calorimetric measurements of energy retention to predict the relationship between energy retention and weight gain. The agreement between observed and predicted live-weight gain was good at the lower body weights and on the lower ration. For fatter animals eating the high ration at higher body weights, live-weight gains were less than predicted.

A note on the recovery of polyethylene particles from faeces an d rumen contents of steers

SUMMARYTwo experiments were conducted with three types of polyethylene particles to establish their retention time in castrated male cattle (steers) offered diets which contained predominantly cereals ad libitum. The particles were (1) ‘Ruff Tabs’, a corrugated particle of dimension 1·27 × 0·63 × 0·95 cm3 and subsequently referred to as RT and (2) and (3) plain plastic rods of 1·27 cm length and 0·32 cm (BP) or 0·63 cm (RBP) diameter.In the first experiment with steers weighing 170 or 260 kg, 1 kg of RT particles were excreted in the faeces at a similar rate by the steers of different weights whereas BP particles passed out in the faeces more slowly in the lighter steer.In the second experiment 30 steers weighing 440 kg were slaughtered at 7, 14, 28 and 42 days after dosing with 1 kg of BP, RT or RBP. The recovery of RT was significantly lower (P < 0·05) than that of BP 7 days after dosing and this difference was also found at 14 and 28 days. RBP behaved like BP up to 14 days but thereafter the rate of passage of RBP was faster than tha t of BP and recovery from the rumen approached that of RT.

A note on the effect of polyethylene particles on rumen metabolism of strees

SUMMARYExperiments were carried out to determine the effects of giving 1·36 kg of ‘RuffTabs’, polythene particles of dimension 1·27 × 0·63 × 0·95 cm3 (RT) to castrated male cattle (steers) given an all-concentrate diet, on the outflow of fluid from the rumen, on rumination and on the molar proportions of volatile fatty acids produced in the rumen.RT reduced the flow of fluid from the rumen of steers, given a restricted amount of an all-concentrate diet, from 4·65 to 2·75% rumen volume/hr. RT had no effect on the total time spent daily in ruminating and eating. The molar proportions of volatile fatty acids were unaffected by RT in steers which were given the diet ad libitum but when RT was given to steers offered a restricted allowance of feed there was a highly significant (P < 0·001) reduction in acetic and an increase in butyric, valeric and caproic acids.The feed intake of the steers was unaffected by RT.