Age Of Castration Research Articles

The effect of age and method of castration on plasma cortisol in beef calves

Plasma cortisol concentration (PCC) was measured at 0, 2 min, 3, 6, 12, 24 and 30 h in 36 calves castrated at 78 ± 12 d of age or 167 ± 14 d of age by either surgical or burdizzo methods or left as bulls (control). At 2 min, bull calves had greater (P < 0.05) PCC (22.2 ± 4.5 μg L−1) than burdizzo castrates (10.4 ± 3.0 μg L−1) while surgical castrates were intermediate and not different (P > 0.05) from either group (11.4 ± 2.9 μg L−1). There were no further differences between groups until the 30 h postcastration bleed when PCC for bull calves (22.1 ± 6.0 μg L−1) was greater (P < 0.05) than surgical (7.4 ± 2.3 μg L−1) and burdizzo (9.5 ± 2.4 μg L−1) castrates. At late castration, there was an immediate rise in PCC 2 min postcastration for burdizzo castrates (32.0 ± 3.1 μg L−1) which was greater (P < 0.05) than surgical castrates (18.6 ± 4.1 μg L−1), while bull calves (23.0 ± 1.9 μg L−1) were intermediate and not different from either castration group. At 3 h, PCC of surgical (44.4 ± 4.2 μg L−1) and burdizzo (38.6 ± 8.3 μg L−1) castrates was greater (P < 0.05) than bull calves (24.1 ± 8.5 μg L−1). At 6 h, surgical castrates had a greater (P < 0.05) PCC (27.5 ± 5.4 μg L−1) than burdizzo castrates (15.3 ± 0.41 μg L−1) but neither group was different (P > 0.05) from bull calves (17.2 ± 2.7 μg L−1). There were no further differences between groups up to 30 h postcastration. It was concluded that castration at a young age caused no physiologically detectable stress while physiological stress was detectable in older calves but that, in older calves, burdizzo was less stressful than surgical castration. Average daily weight gain did not differ (P > 0.05) between castrated and bull calves. Key words: Castration, plasma cortisol, age, beef calves

The postnatal demasculinization of sexual behavior in the Japanese quail ( Coturnix coturnix japonica)

Three experiments were performed to analyze the time course of demasculinization in the Japanese quail and to test the activating and organizing effects of estradiol (E2) in adult sexually active birds. In Experiment 1, males and females were castrated at the age of 1 day or 1, 2, 4, and 6 weeks and treated as adults with testosterone (T). The age of castration had no effect on behavior and morphology in males. Plasma gonadotrophins (LH and FSH) were, however, higher in males castrated at or before than in those castrated after 2 weeks of age. This suggests that postnatal testicular secretions have organizing effects on the pituitary activity. Females which were castrated before 1 week of age were less sensitive to the activating effects of T than males, but were not fully demasculinized. The demasculinization of different reproductive characteristics such as male sexual behavior, cloacal gland size, and weight of the syringeal muscles is achieved in females at different times posthatching. In Experiment 2, castration of male and female quail at the ages of 4 days or 4 weeks confirmed that postnatal ovarian secretions contribute to the full behavioral and morphological demasculinization of females. It is easier to elicit mounting in T-treated females when they are tested in their home cage instead of a test arena. This difference was not observed in males. During Experiment 3, it was impossible to demasculinize sexually active adult males or females by treatment with Silastic implants of E2. E2 did not maintain sexual behavior in ovariectomized females showing male sexual behavior when treated with T but maintained the behavior in males.

Stereotyped behavior elicited by amphetamine in the rat: Influences of the testes

Castrating male rats in adulthood increased the duration of stereotyped behavior in response to 5 mg/kg injections of d-amphetamine sulfate; exogenous treatment with testosterone propionate (TP) reversed this effect. Ovariectomy in adulthood had no effect on stereotypy, but TP injections reduced stereotyped responding by ovariectomized females. Thus testosterone exerts comparable effects on stereotypy elicited by amphetamine in both sexes. Males castrated at 1, 6 or 10 days of age but not males castrated in adulthood displayed levels of stereotyped behavior comparable to those of ovariectomized females when all animals were given TP in adulthood. Control experiments indicated that age of castration rather than time since castration was the critical factor, implying that secretions of the testes early in life exert effects on systems that regulate the responses of adults to amphetamine.

Effects of testrosterone replacement on the recovery from increased emotionality, produced by septal lesions in prepubertal castrated male rats

One hundred forty-seven male rats were studied in an attempt to relate testosterone replacement therapy to the recovery process from increased emotionality following septal lesions. The following groups were used: (a) animals castrated at each of the ages 22–31 days and either testosterone replaced or vehicle injected or not injected; (b) intact animals which were either testosterone injected or vehicle injected or not injected. All animals underwent bilateral septal lesions at about the age of 65 days, and their emotionality was rated 1 day, 3 days and 7 days postoperatively. Recovery from increased emotionality was found to be dependent on age of castration. Testosterone replacement, although efficient in restoring sexual functions, did not have an effect on the recovery process.

THE EFFECTS OF CASTRATION ON BODY COMPOSITION, ADIPOSE TISSUE CELLULARITY AND LIPID AND CARBOHYDRATE METABOLISM IN ADULT MALE RATS

Gonadal hormones affect body composition, food intake, weight gain and serum lipids in numerous species including man. In this study, mature male Sprague-Dawley rats were castrated or sham-operated at 16 weeks of age. During the 6-week observation period with weekly records of food intake and weight gain, these parameters were significantly lower in the castrated group. The decrease in food intake in this group could not account for the difference in body weight between the groups, indicating a lower feed utilisation in the castrates. At sacrifice accessory reproductive organs, the levator ani muscle, thymus and adrenals were dissected for determination of organ weight and histology, revealing significant reductions in the accessory reproductive organs and levator ani of the castrates. The thymus was significantly heavier in the castrated animals. No differences were found in the adrenals. Two of the sham-operated animals had signs of accidental functional castration. The proportion of body cell mass and total lipid of the carcass was the same in both groups. Significant reductions in adipocyte weights were found in the epididymal depots of the castrated rats. Blood samples taken at sacrifice in pentobarbital anaesthesia were analysed for glucose, insulin, triglycerides, cholesterol, FFA, glycerol and protein. Statistically significant reductions in triglycerides and protein were recorded in the castrated animals without any significant changes in the other parameters studied. The results are discussed with reference to the age of castration and the importance of the reduced food intake in castrated animals.

Enzymatic oxidation and reduction of C19-delat5-3beta-hydroxysteroids by hepatic microsomes. 3. Critical period for the neonatal differentiation of certain mixed-function oxidases.

The gonadal dependence of certain hepatic enzymes has been studied in neonatal and pubertal rats with 14C-dehydroepiandrosterone (DHA). Microsomes from rats of 20, 40, 70 and 105 days of age produced 7α- and 7β-OH-DHA, and 7-keto-DHA in addition to 16-oxygenated products and A5-diol. The rates of 7α-hydroxylation (nmoles min-1mg-1) characteristic of adult males had appeared at 40 days of age and progressively increased thereafter. This transformation by tissue from females decreased from the values of 20-day-old animals to a constant minimum level. The formation of 16-keto-A5-diol, 16α-0H-DHA and A5-triol was significantly reduced from normal values in 70-day-old males which had been castrated at 1, 10 or 40 days of age. The rates of production of these 16-oxygenated metabolites were proportional to the age of castration, with neonatally castrated males having the lowest rates, similar to those of intact adult females. The pubertal increase of the 7α-hydroxylase activity was also prevented by castration o...

Influence of age and of testosterone on the response of male rats to parachlorophenylalanine.

1. Castrated male rats and male rats that had been castrated as well as adrenalectomized, showed hypersexual behaviour 24 h after treatment with parachlorophenylalanine (PCPA), as did intact rats.2. A dose of PCPA 100 mg/kg was sufficient to induce mounting behaviour; this dose lowered the cerebral 5-hydroxytryptamine (5-HT) to about 50% in 24 h and further to 40% in 72 hours.3. Groups of juvenile male rats treated chronically with PCPA 100 mg/kg or 50 mg/kg, or with testosterone propionate 1.25 mg, showed hair loss after three weeks of treatment (6 injections), because of increased social interaction.4. Groups of intact male rats 9-11 weeks old given testosterone propionate 1.25 mg subcutaneously, showed mounting behaviour 3-5 h after the injection which was indistinguishable from the behaviour seen 24 h after treatment with PCPA 100 mg/kg. The 5-HT content of the brain was not altered by testosterone.5. The number of rats which showed mounting after PCPA treatment did not change with age, but the younger rats made more mounts in the observation time than rats more than three months old.6. The age of castration (3 weeks or 4 months) did not influence the results.

THE EFFECTS OF SEX AND AGE OF MALE AT CASTRATION ON GROWTH AND CARCASS QUALITY OF YORKSHIRE SWINE

The effects of sex and age of castration of males on growth rate, feed efficiency and carcass characteristics in bacon type swine were measured using 16 pigs each as gilts, entire boars, and boars castrated at birth, 6, 12, 16, and 20 weeks of age. Castration at 20 weeks was too late since some pigs reached 200 pounds live weight before that age. Boars consumed less feed daily than barrows and gilts, were thinner in loin fat, and yielded a higher percentage of shoulder than gilts. The carcasses of boars and gilts were longer, had less fat covering over the shoulder and back, a larger area of loin, and a higher iodine number than those castrated late. Acceptability tests showed that sex or age of castration did not affect the flavour, odour, or tenderness of the meat.Purebred breeders can delay castration for better selection of boars without any serious effect on growth, physical carcass characteristics, and feed requirements. Although the market discriminates against boars, it appears questionable whether castration is necessary when boars are slaughtered at 200 pounds before they reach the age of 150 days.

The Effect of Age of Castration upon Rate and Economy of Gain and Carcass Quality of Beef Calves

The Effect of Age of Castration upon Rate and Economy of Gain and Carcass Quality of Beef Calves