Young Intact Males Research Articles

Meat quality characteristics of Tankwa goats from Carnarvon, Northern Cape

The aim of this study was to determine the post-mortem meat quality characteristics of extensively reared Tankwa goats to identify the most favourable age and sex for slaughter. Twenty-four goats, representing five groups, namely young intact males (G1), young females (G25), young castrates (G3), old males (G4), and females (G5), were selected directly from their natural grazing environment and slaughtered to evaluate meat quality characteristics. The Musculus longissimus and Musculus semimembranosus from the right side of each carcass were evaluated. Dressing percentage and chilling losses did not differ significantly between the groups. Ultimate pH at 24 hours after slaughter was higher for males than females. Meat colour, water-holding capacity, and sarcomere length did not differ between groups. Myofibril fragmentation length (MFL) was on average less than 40 μm and was shorter in younger animals. There were no significant differences in cooking loss and thawing loss for M. longissimus and M. semimembranosus between groups. There were no significant differences in Warner-Bratzler shear force (WBSF) between groups for meat from the M. semimembranosus. However, WBSF of the M. longissimus was higher in older animals. Overall, meat from these goats can be regarded as tender because meat with a WBSF below 5.5 is considered as tender.

Mouse Bioassay forin vivoScreening of Oestrogen and Progesterone Antagonists

This study tested and compared the anti-proliferative and proliferative activities of two anti-oestrogens and three anti-progestins on four separate mouse model systems: young intact and adult ovariectomized (OV-X) females, and young intact and adult castrated males. Pure steroidal anti-oestrogen ICI 182,780 (ICI) decreased mammary and uterine growth stimulated by endogenous hormones in young intact females and by exogenous hormones [progesterone (Prog), 17beta-oestradiol (E) or E plus Prog] in both young intact and adult ovariectomized (OV-X) females. Non-steroidal anti-oestrogen EM-800 (EM), on the other hand, had no effect on mammary and uterine growth stimulated by endogenous hormones in young intact females and in adult OV-X females. Uterine growth was even stimulated by EM alone, and a combination of EM plus Prog not only stimulated uterine growth but also mammary growth (an oestrogenic agonistic activity). However, EM showed anti-oestrogenic activities in both mammary and uterine tissues in females treated with E or E plus Prog. In males, ICI and EM decreased mammary growth stimulated by exogenous hormones (E or E plus Prog) in both young intact and adult castrated animals. In young intact, but not in adult castrated males, ICI increased seminal vesicle growth affected by both endogenous and exogenous (Prog, E or E plus Prog) hormones. EM, on the other hand, decreased seminal vesicle weights in E or E plus Prog and increased its weights in Prog-treated young intact males. Thus, under certain conditions EM possess mixed agonist and antagonist activity in the mammary gland, uterus and seminal vesicles. Norethindrone acetate (NA)-stimulated mammary growth was decreased by anti-progestins onapristone (ON), RU 46556 (RU), and RU 38486 (MI) by 34-59% in females and by 35-93% in males. Uterine weights of NA-treated females were decreased by ON and RU by 29-55% but not by MI. In NA-treated young intact males, seminal vesicle weights were stimulated by RU (by 63%) and not affected by ON and MI. In NA-treated adult castrated males, seminal vesicle weights were decreased by ON, increased by RU and not affected by MI. The results obtained in these and our earlier studies show clearly that mouse four-model systems could serve as in vivo tool for the detection of steroid hormone agonist and antagonist activities of natural and man-made chemicals.

Role of androgens in mediating renal injury in aging SHR.

Men have an increased risk of cardiovascular and renal diseases and develop greater renal injury despite similar levels of blood pressure when compared with women. The mechanisms responsible for this predisposition are unknown. Using the spontaneously hypertensive rat (SHR), we have found that androgens play an important role in the development of hypertension in young male SHR. However, the role that androgens play in age-related renal injury and dysfunction in SHR is unknown. Our hypothesis was that despite reductions in serum testosterone with age, androgens mediate renal injury and dysfunction in male SHR. Male SHR were castrated at 8 months of age, studied at 18 months of age, and compared with age-matched, intact males and young intact males (4 months). Serum testosterone was reduced by 30% in aging males compared with young SHR. With castration, blood pressure (mean arterial pressure [MAP]) was decreased by >20 mm Hg compared with old males, glomerular filtration rate (GFR) was increased by >35%, and renal vascular resistance (RVR) was reduced by >40%. MAP, GFR, and RVR in castrated, old males were similar to values in young males. With castration, glomerular sclerosis was reversed and proteinuria was also decreased by >80% when compared with old intact males. In addition, in castrated old males, plasma renin activity was decreased by 30% compared with old males and by 60% compared with young rats. The data support the hypothesis that despite a reduction in testosterone with age, androgens play an important role in age-related renal injury and dysfunction in SHR.

Morphometric Criteria for Bioassay of Agonist and Antagonist Actions of Steroid Hormones on the Mammary Gland

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Sensitivity and Specificity of the Bioassay of Estrogenicity in Mammary Gland and Seminal Vesicles of Male Mice.

Young intact (18 days old) and adult castrated males of CBA and C3H/Di mice were used for measuring the estrogenicity on the basis of growth response of mammary epithelial structures and the weight of seminal vesicles. It was demonstrated that heavier young males had disproportionally heavier seminal vesicles (sex steroid-responsive organs) than small animals at day 33 of age (that is on the day when experimental animals were killed and organs dissected). However, the weight of the spleen (sex steroid-nonresponsive organ) was proportionally related to body weight. To minimize variability in hormone responsiveness, all animals were weighed at the age of 18 days and only males weighing 8±1 g were used for hormone treatment. The percentage area of mammary fat pad occupied by mammary epithelial structures was progressively increased by 17ß estradiol from dose 0.01 µg.d-1. The maximum effective dose of estradiol was 0.1 µg.d-1 and dose 10 µg.d-1 of estradiol decreased mammary size to control level (inverted-U-shaped dose-response curve). Progesterone alone stimulated mammary growth only in high doses (500 µg.d-1 and higher) in young intact males, but had no effect on mammary growth in adult castrated animals. In young intact males, estradiol alone, or progesterone alone decreased the weight of seminal vesicles. No such inhibitory effect of these hormones was noted in adult castrated males. Progesterone acted synergistically with estradiol to produce higher mammary growth compared to that in males treated with estradiol alone. In the presence of progesterone seminal vesicles weight was decreased by estradiol given in such low doses as 0.001 µg.d-1 of estradiol, which is 10 times lower than that effective in animals treated with estradiol alone. On the other hand, in the adult castrated males a combination of estradiol plus progesterone stimulated seminal vesicles weight. The effects of a combination of estradiol plus progesterone in the mammary gland were mimicked by norethindrone acetate (a synthetic steroid exhibiting progestantial and estrogenic activities) and inhibited by both testosterone and cortisol. Estradiol, progesterone, norethindrone acetate, or testosterone did not affect spleen weight and size of mammary lymph nodes. However, cortisol significantly decreased not only spleen weights but also size of mammary lymph nodes. These results show that simultaneous evaluation of mammary gland growth, seminal vesicles, and the spleen weight in the same animal is suitable for bioassay of estrogenicity as well as for detection of androgenic and antiandrogenic activities.

Características da Carcaça e Qualidade da Carne de Tourinhos Alimentados com Dietas de Alta Energia

Foram alimentados 36 tourinhos ¾ Europeu ¼ Zebu com dietas contendo 9, 15 e 21% de bagaço de cana-de-açúcar in natura (BIN) na matéria seca. Os animais, com peso inicial de 257 kg, foram abatidos após 138 dias, com 435 kg de peso. Foram realizadas mensurações na carcaça e da composição física do corte das 9-10-11ª costelas. Amostras dos músculos Longissimus dorsi e Supraspinatus, maturadas durante 0, 7 e 14 dias, foramanalisadas quanto à textura e cor. A quantidade de gordura renal e pélvica foi maior para os tratamentos 9 e 15% de BIN. Houve tendência para maior espessura de gordura subcutânea nos tratamentos 9 e 15% de BIN. Os diferentes níveis de fibra na dieta não alteraram a composição física e as características de carcaça, porém maior acúmulo de gordura nas regiões inguinal e pélvica foi observado em tratamentos com maior teor de concentrado. A textura objetiva (WB) apresentou diferença entre os três grupos de bifes maturados, nos dois músculos testados; o grupo com 14 dias de maturação foi mais macio que o tempo 7, e este, mais macio que o tempo 0. Não foram encontradas diferenças entre os tratamentos nutricionais para a característica de cor, entretanto, houve efeito significativo para o período de maturação. A carne maturada (tempos 7 e 14) foi mais macia e brilhante, e suas cores, mais realçadas. A maturação teve grande impacto sobre a maciez em touros jovens produzindo carcaças de 230 kg e com 4 mm de espessura de gordura.

Exigências Líquidas de Energia e Proteína de Tourinhos de Dois Grupos Genéticos Alimentados com Dietas de Alto Teor de Concentrado

Avaliou-se a composição corporal de 42 tourinhos ¼ B. indicus x ¾ B. taurus, de raça paterna Britânica (Shorthorn) ou Continental (Guelbvieh) com 9 meses e 243 kg de peso vazio inicial (PVzi). Destes, seis animais foram abatidos para obtenção da composição corporal inicial do lote. Os 36 animais restantes foram confinados com dietas contendo 9, 15 e 21% de bagaço de cana in natura (BIN) na MS. Não houve efeitos significativos da interação entre tipos raciais e níveis de fibra para as variáveis analisadas. O efeito do tipo racial não alterou a composição do ganho de peso vazio (GPVz), tendo os animais Britânicos apresentado 28,9% de gordura e 3,75 Mcal/kg, enquanto os animais Continentais apresentaram 28% de gordura e 3,67 Mcal/kg de GPVz. Os animais Britânicos apresentaram teores numéricos maiores de gordura e energia, apesar de apresentarem média de PVzi e ganho de peso vazio final (GPVzf) menores que os Continentais. O efeito de fibra não foi significativo, mas animais recebendo dietas com 15% de BIN apresentaram GPV numericamente maior (1,2 kg/d), que os animais que receberam 9% e 21% de BIN (1,1 kg/d). Os diferentes níveis de BIN não alteraram a composição do ganho, mas a composição do GPVz dos animais que receberam 15% de BIN apresentaram maiores teores numéricos de lipídeo e energia, 31% e 3,94 Mcal/kg de GPVz. Os animais submetidos aos tratamentos 9 e 21% de BIN apresentaram respectivamente, 28,6% e 25,7% de lipídeo e 3,72 e 3,46 Mcal/kg de GPVz. A composição do GPVz e as exigências líquidas de energia e proteína dos tourinhos ¾ europeus filhos de vacas Caracu x Nelore com touros Guelbvieh ou Shorthorn foram semelhantes às observadas para machos não castrados de tamanho corporal grande ou grau de estrutura corporal próximo a 8 na escala 1-9.

Age-related deficits in brain estrogen receptors and sexual behavior of male rats.

Neural estrogen receptors (ER), serum testosterone (T), estradiol (E2) and luteinizing hormone (LH), and masculine sexual behavior were measured in young (5 months) and old (24 1/2 months) Fischer 344 male rats. We found that old intact males, which displayed significantly lower levels of sexual behavior, T, and LH than young intact males, also had lower levels of nuclear ER (ERn) in the amygdala (AMG). The age difference in ER binding did not appear to be a consequence of altered blood E2 levels because circulating E2 did not differ between the two age groups. Gonadectomy eliminated ejaculatory behavior and significantly reduced ERn in young males. When we administered exogenous T to gonadectomized males in doses that approximated levels found in young intact males, we found that sexual performance of old males was stimulated to precastration levels but not to levels found in young males. Moreover, such treatment failed to increase ERn in the AMG of old males to the levels measured in the AMG of young males. These results suggest that there is an association between the inability of T to increase ERn concentration in the AMG and the deficits in sexual performance that are characteristic of old males. Thus, the capacity of neural tissue to bind estrogen, presumably derived from circulating T, may be a limiting factor in the determination of androgen responsiveness in aging males.

Evaluation of palatability of lamb, mutton, and chevon by sensory panels of various cultural backgrounds

Palatability of loin chops and leg steaks from thirty young intact males and thirty aged females of three sheep breeds (Rambouillet, Karakul, Barbados) and two goat breeds (Angora, Spanish) was evaluated by two untrained sensory panels (foreign and domestic) comprised of ten members each. Panelists evaluated flavor, juiciness, tenderness, and overall palatability. Sensory panel ratings assigned by foreign panelists generally were higher than were those by domestic panelists. Samples from Rambouillet, Karakul and Barbados sheep were generally assigned higher palatability ratings than were those from Angora or Spanish goats.

Age-related deficits in brain androgen binding and metabolism, testosterone, and sexual behavior of male rats

Brain androgen binding and metabolism, serum testosterone (T), and sexual behavior were measured in old and young male Fischer 344 rats. After completion of sexual behavior tests, blood was collected for T assay and brains were removed for simultaneous measurements of cytosolic (ARc) and nuclear (ARn) androgen receptors and aromatase activity (AA) in the preoptic area (POA), hypothalamus (HYP) and amygdala (AMG). In Experiment 1, old and young intact males were examined. None of the old males ejaculated in any of the tests of sexual behavior whereas all of the young males ejaculated. The old males had lower levels of serum T, lower levels of ARn in the POA and HYP and lower levels of AA in the POA. The ARc levels of the old and young males did not differ. Experiment 2 was designed to determine if the deficits in brain androgen binding and metabolism were due to low levels of T. Old and young T-treated gonadectomized (GX-T) males and young intact (I) males were examined. T levels were comparable in the young and old GX-T males and were higher in each of these groups than in the young I males. In sexual behavior tests, all of the young but only 25% of the old GX-T males ejaculated. Although ARn levels in the old GX-T males were lower than in the young GX-T males, they were comparable to the young I male levels. No age-related differences in T induction of AA were observed. These data suggest that there is an association between decreased T levels in old males and decreased ARn and AA levels but no association between decreased T and decreased sexual behavior. Thus the age-related deficits in behavior are probably not due to changes in ARn and AA.

Sexual performance of old and young male rhesus macaques following treatment with GnRH

GnRH has been reported to facilitate sexual performance in a number of species. To determine whether the same was true for rhesus monkeys we measured sexual behavior and serum levels of testosterone (T) and luteinizing hormone (LH) following control tests and after treatment with two doses of GnRH. In the first experiment, old intact (N = 11) and old T-implanted, castrated (N = 4) rhesus macaques were examined. Mean intromission rate of old intact males was significantly lower following treatment with 100 μg of GnRH than following control injections. Other measures of sexual behavior did not differ across treatments. There were no significant treatment effects among the old castrated males. The failure to facilitate sexual performance may have been due to the age of the males and not to the species under study. Thus, in a second experiment the effects of GnRH were examined in young rhesus males. Again, there was no facilitation of sexual performance. This cannot be accounted for by a failure of GnRH to produce a physiological response. For both old and young intact males serum levels of LH and T increased significantly after treatment with both doses of GnRH. LH but not T levels increased significantly in the T-implanted males.

Carcass and offal yields of sheep and goats as influenced by market class and breed

Sheep and goats ( n=120) of two market classes and five breeds were slaughtered and weights of carcass and offal items were obtained. Offal item yields were computed as percentages of live weight minus weight of gastro-intestinal tract and its contents. Sheep weighed more ( P < 0.05), dressed higher ( P < 0.05) and had lower ( P < 0.05) yields of most dress-off items than goats of comparable market class. Aged female and young intact male sheep or goats (within species) differed ( P < 0.05) in heart, liver, blood and pelt yields; within breeds, aged female and young intact males did not differ ( P < 0.05) in live or carcass weights, dressing percentage or lung percentage. Angora goats dressed lower ( P < 0.05) than Spanish goats. Karakul sheep dressed higher ( P < 0.05) than all other breeds of sheep and had higher ( P < 0.05) carcass weights and lower ( P < 0.05) head percentages. Data of this study emphasize importance of consideration of yields of all offal items that can be used as food rather than simply basing live value of sheep and (or) goats on quantitative or qualitative aspects of their carcasses when decisions regarding species, breed or market class are to be made for other parts of the world.

Carcass grades, rack composition and tenderness of sheep and goats as influenced by market class and breed

Compared to Spanish and Angora goats, sheep had heavier ( P < 0.05) carcass weights, more youthful USDA overall maturity scores, higher flank streaking scores, higher USDA leg conformation scores, larger longissimus muscle areas, and produced loin chops with lower shear force values. Rambouillet sheep had ( P < 0.05) higher scores for USDA skeletal and overall maturity, more feathering and flank streaking, higher USDA leg conformation scores and produced loin chops with lower shear force values than Barbados and Karakul sheep. Karakul sheep (especially the young intact males) had higher adjusted fat thicknesses than the other sheep and goat breeds due to heavy fat deposition near the dock. Racks from young intact males tended to have higher percentages of lean than racks from aged females within most sheep and goat breeds.

Sexual behavior in response to testosterone in old long-term-castrated rhesus males

The sexual behavior of 20-year-old long-term-castrated and intact male rhesus macaques ( Macaca mulatta) was observed. In the first experiment we compared the sexual behavior of males tested in 1980 with their performance in 1970 (before castration and sham castration) and in 1971 (1 year after the operation). In 1971 and 1980, the castrated males were tested while under testosterone propionate treatment. The castrated and intact males did not differ in any measures of sexual behavior over the 10-year period, but both groups showed a decline in the percentage of tests with intromissions and ejaculations; a decline in the rates of contacting, mounting, and intromitting; and an increase in the latencies to contact, intromit, and ejaculate. In a second experiment, the sexual performances of old castrated and intact males were compared to those of young intact males (8 to 12 years). The intromission rate and the percentage of tests with intromissions were significantly greater in young males than in old intact males, but did not differ from values for old castrated males. The old castrated and old intact males did not differ from each other in these measures. Young males had a higher percentage of tests with ejaculation than either group of old males. We have concluded that old long-term-castrated rhesus males retain the potential to display sexual behavior at levels comparable to those observed in old intact males.