Effect of castration at 10 months of age on growth physiology and behavior of male feral beef cattle

Understanding the effect of sex on energy requirements of hair sheep

Differences and/or similarities in the influence of sex class for hair sheep requirements remain inconclusive. Knowledge of energy requirements allows well-formulated diets to be provided which is crucial for improving animal production. We aimed to determine the effect of sex class on the net energy requirements of growing hair sheep in a multi-study approach. We used a data set composed of individual measurements of 382 hair sheep (299 non-castrated and 83 castrated males) from 11 studies that used the methodology of comparative slaughter. Net energy requirements for maintenance (NEm) were obtained by the regression between heat production and metabolizable energy intake. The metabolizable energy requirements for maintenance (MEm) were calculated by the iterative method, and the efficiency of use of metabolizable energy for maintenance (km) was obtained by NEm divided by MEm. The net energy requirements for gain (NEg) were estimated from retained energy (RE) against empty BW gain (EBWG). The efficiency of energy use for weight gain (kg) was obtained from the relationship between RE and the energy metabolizable intake for gain, removing the intercept. There was an effect of sex on NEg and two equations were generated: NEg (MJ/day) = 1.040 (±0.04055) × EBW0.75 × EBWG0.8767(±0.03293) and NEg (MJ/day) = 1.040 (±0.04055) × EBW0.75 × EBWG0.8300(±0.03468) (R2 = 0.86; MSE = 0.0037; AIC = -468.0) for non-castrated and castrated males, respectively. Sex class did not affect kg (P > 0.05) and one kg was generated (0.29). Sex did not affect kprotein (P = 0.14) and kfat (P = 0.32), assuming an average deposition efficiency of 0.27 for protein and 0.78 for fat. The NEm and MEm did not differ (P > 0.05) between sex classes, with a value of 0.272 and 0.427 MJ/kg0.75 EBW per day, respectively. The km observed was 0.64. In conclusion, non-castrated and castrated male hair sheep have similar maintenance energy requirements although energy requirements for gain differed among them. The Committees overestimate the gain and maintenance requirements for hair sheep. Therefore, the equations generated in this study are recommended.

Effects of uni and bilateral castration on growth performance and lipid metabolism in yellow cattle

This study was conducted to examine the influence of uni and bilateral castration on growth performance and lipid metabolism in yellow cattle. Eighteen 9-month-old healthy yellow cattle (average body weight 184.03 ± 4.09 kg) were selected and divided into three groups: The uncastrated cattle (C), half castrated cattle (HC) and full castrated cattle (FC). The results showed that the growth rate of FC group was significantly reduced as compared to HC and C group, while the feed to gain ratio exhibited an opposite trend. The concentrations of triglycerides (TG), low-density lipoprotein cholesterol (LDL) and high-density lipoprotein (HDL) were increased significantly in FC group from day 60 to the end of the trial compared to HC and control groups. Serum testosterone concentration of FC group cattle was decreased from day 60 to 120 d of the trial compared to HC and control groups. The concentration of the lauric acid in FC cattle was significantly increased from the HC and control groups. In the FC group, the acetyl-CoA carboxylase alpha (ACACA), ACC and fatty acid synthase (FAS) gene expression levels were significantly higher compared to control and HC groups. Our results of this study suggest that bilateral castration increased the lipid metabolism and fatty acid composition compared to unilateral castrated and un-castrated cattle.HighlightsBilateral castration alters the growth performance in yellow cattle.Bilateral castration alters hormones levels and lipid metabolites levels in serum.Bilateral castration improves the lipid metabolism and fatty acid profile.

Castration alters the cecal microbiota and inhibits growth in Holstein cattle

To determine the effects of castration on growth performance, serum hormone levels, cecal microbiota composition, and metabolites in cattle. A total of 18 Holstein bulls and steers were divided into bull and steer groups and randomly assigned to 3 pens (3 cattle per pen, and each cattle were separated by a fence) to determine the average daily gain (ADG), daily dry matter intake (DMI), and feed efficiency (G/F). After the finishing trial, six cattle per group were randomly slaughtered. Serum was collected to measure the hormone concentration, and the cecal content was collected to measure the pH, short-chain fatty acids, and digestive enzyme activities. Metagenome sequencing and untargeted metabolomics were used to investigate the microbiota composition, functional profiles, and differential metabolites of the cecal contents. We found that castration significantly decreased ADG, DMI, and G/F in cattle (P < 0.05). The serum testosterone, thyroxine, growth hormone (P < 0.05), and triiodothyronine (P < 0.01) concentrations significantly decreased in the steer group when compared to those of the bull group. The activities of cellulase, xylanase, pectinase, and β-glucosidase (P < 0.05) significantly decreased in the steer group, whereas the activities of lipase and α-amylase significantly increased. Moreover, castration significantly decreased the relative abundance of Ruminococcaceae_bacterium, Treponema_porcinum, Oscillibacter_sp. (P < 0.05), and Alistipes_senegalensis (P < 0.01), whereas the relative abundance of Phocaeicola_plebeius (P < 0.05) was significantly increased. Also, the relative abundance of Phocaeicola_plebeius was negatively correlated with testosterone levels, and the function of the cecal microbiota was enriched in the GH29 and GH97 families in the steer group. Metabolomic analysis indicated that castration increased the levels of L-valine, L-phenylalanine, L-aspartic acid, L-isoleucine, L-lysine, methionine, L-glutamic acid, and L-leucine, while decreasing the levels of α-ketoglutaric acid through the 2-oxocarboxylic acid metabolism pathway. In addition, α-ketoglutaric acid was negatively correlated with Oscillibacter_sp. (P < 0.01). Overall, castration can inhibit cattle growth by altering the composition of the cecal microbiota. Therefore, this study provides a theoretical and practical basis for improving the growth performance of steers.

Silva S, Netto AS. Castration age and growth, meat production and meat quality of Nellore male cattle

Castration in beef cattle production has been proposed to reduce sexual and aggressive behaviour, increase carcass fat deposition, and improve meat quality traits, such as tenderness and juiciness. The aim of the present study was to evaluate the effects of the age of castration on performance, subprimal yield and meat quality of Nellore cattle raised on a pasture system. A total of 24 Nellore males were raised in a grass-fed system with Brachiaria brizantha since birth until slaughter (at 30 months old). Three treatments were assigned: castration at weaning (CW); castration at 20 months old (C20); and intact bulls (NoC). Males were weighed, and muscle and fat thickness were periodically evaluated by ultrasonography. The cold carcass weight, dressing and carcass pH (pH 24), and subprimal cut weights were recorded after 24 h of chilling. Samples of Longissimus lumborum (LL) were taken to measure meat quality traits. Animals that were castrated at weaning had lower bodyweight after 10 months of age with no changes in the supplement intakes, average daily gain, hot carcass weight and cold carcass weight compared with NoC. Intact males had greater cooking losses and carcass yield compared with others, with no differences for LL pH 24 according to the treatments. The castration did not change the LL muscle area, but decreased total forequarter, chunk, shoulder and eye of round weights, and increased the back fat over LL and rump fat. Animals castrated at weaning had higher marbling compared with others. In addition, regardless of age, castration improved tenderness, increased LL total lipids and decreased moisture compared with NoC. For sensory property, steers castrated at 20 months of age had lower juiciness, and NoC had a greater global sensory property compared with steers castrated at 20 months old. In conclusion, steers castrated at weaning had lower growth rate, final bodyweight and meat production compared with intact males. However, when castration was performed at 20 months, animals did not differ in most cases from castration at weaning and NoC. Tenderness was improved by castration, but sensory traits did not differ between groups.

Effects of immunocastration performed at two live weights on the growth physiology, temperament and testicular development of feral beef bulls

The aim of this study was to examine the effect of administering an anti-gonadotropin-releasing hormone vaccine (Improvac^® , developed for pigs) on the performance, temperament, testicular development, and hormone and metabolite profiles of feral bulls (Bos taurus) vaccinated at two different live weights (LW). In all, 16 Serrana de Teruel animals were involved in this 2 x 2 factorial design using the factors LW (LIGHT vs. HEAVY) and vaccine treatment (control, C vs. vaccinated, VA). All animals received the same diet (ad libitum concentrate plus straw) over a 164-day fattening period. Temperament was assessed using chute and flight speed tests. Testicular diameter and subcutaneous fat thickness were recorded. Testosterone, IGF-1, urea, NEFA, and creatinine profiles were analyzed. Bull weight gain was reduced in VA compared to C animals, regardless of the initial LW. The vaccine did not affect the temperament tests, subcutaneous fat thickness or NEFA and creatinine concentrations and had minor effects on linear body measures. The vaccine inhibited testicular growth, reduced plasma testosterone to residual levels, and increased urea concentrations. LIGHT-C animals exhibited increased mean plasma IGF-1 concentrations compared to LIGHT-VA animals. In conclusion, vaccination reduced bull growth and sexual development irrespective of LW at immunization.

Effect of testosterone on the differentiation control of stromal vascular cells isolated from longissimus muscle of Hanwoo beef cattle

Testosterone, as an influential factor in marbling score, requires strict management for uniform development of adipocytes in-between muscle bundles. Present study investigated effect of castration timing and testosterone levels on adipocyte development using SVCs. Isolated SVCs exhibited classical MSC markers, CD31^-, CD34^-, CD45^-, CD90⁺, and CD105⁺. ELISA analysis indicated that serum testosterone concentration was highest in non-castrated calves while no significant difference was observed between female, early and late castrated calves. CCK-8 assay showed that concentration of testosterone had no effect on cell proliferation. However, the real-time PCR demonstrated that 20 ng/ml of testosterone suppressed expression of preadipocyte markers, pref-1 and zfp423, but encouraged expression of myoblast markers, myf5 and myoD, via the AR. Consequently, expression of adipogenic markers C/EBPα and PPARγ, as well as accumulation of triglyceride, were decreased in 20 ng/ml testosterone treatment under adipogenic conditions. These findings suggest that by castrating calves before level of testosterone increases, may improve marbling development in the Hanwoo beef industry.

Effects of an anti-gonadotrophin releasing hormone vaccine on the morphology, structure and function of bull testes

Castration reduces aggressive and sexual behaviour and provides better carcass quality in bull calves. Vaccination against gonadotrophin-releasing hormone (GnRH) is used as an alternative to surgical castration for the purposes of reducing pain and distress in the animals. Currently, no anti-GnRH vaccine has been authorized for use in cattle in the European Union. The aim of the present study was to assess the effect of an anti-GnRH swine-specific vaccine (Improvac®, Zoetis, USA) on the morphology, structure and function of bull testes. Animals were vaccinated at days 1, 21 and 104 of the experimental period and were classified based on their live weight into the following two groups: LIGHT (172.9 ± 30.00 kg) and HEAVY (323.8 ± 37.79 kg). The scrotal circumference was measured on day 1 and prior to slaughter (day 164). At slaughter, the sperm motility and concentration in the caudae epididymis were assessed. Testes were weighed, measured and examined using ultrasound, and then tissue samples were collected and fixed in formalin. Histological and immunohistochemical studies were performed on the testes to measure the diameter of the seminiferous tubules and assess the testicular cell populations. The results revealed that suppression of testicular development was associated with the use of the Improvac® vaccine, which resulted in a smaller size of the testes and impaired spermatid production. However, the effect of Improvac® was more pronounced and consistent in calves vaccinated at a low live weight than at a heavy live weight, which suggested that vaccination is more effective when calves are vaccinated before or early during puberty. However, testes from calves vaccinated at a low live weight were more prone to the development of intraluminal concretions in the seminiferous tubules.