Short Scrotum Research Articles

The sterility and productivity of young, short scrotum, Merino rams

The sterility and productivity of young, short scrotum, Merino rams

The performance of short scrotum and wether lambs born in winter or spring and run at pasture in northern Tasmania

Summary. The growth of short scrotum and wether lambs was studied in 3 experiments over 2 years, at the Elliott Research Station in northern Tasmania. Short scrotum lambs born in winter grew significantly (P<0.05) faster than wethers from birth to slaughter at 137 days of age. For spring born, short scrotum lambs, the growth advantage was less because of the quality and quantity of pasture available during summer and autumn. Wether lambs were fatter than short scrotum lambs in all experiments, with the slope of the relationship between GR and carcass weight being 0.57 � 0.02 I! 0.42 � 0.01 mmkg (experiment 1); 1.13 � 0.1 1 v. 0.68 � 0.09 mm/kg (experiment 2); and 0.91 � 0.16 v. 0.63 � 0.08 mm/kg (experiment 3) respectively. As carcass weight increased, the difference in carcass fatness increased. There was a shift in the distribution of carcasses according to fat score, with more wether carcasses being allocated high fat scores. Testes weight in the short scrotum lambs showed considerable variation within and between experiments and in all cases the testes were located in a subcutaneous position. There was a poor relationship between testes weight and growth rate. The level of testes development in a proportion of animals indicated that the animals could be fertile.

Sheep testicular gonadotropin binding sites: characterization and changes with surgical shortening of the scrotum.

Gonadotropin receptors in previously frozen (-70 degrees C) sheep testicular tissue were characterized, and methods of assessment of receptor binding activity were established and applied to an investigation of testicular function in the short scrotum ram. Binding of 125I-labelled ovine luteinizing hormone (125I-oLH) and 125I-labelled ovine follicle-stimulating hormone (125I-oFSH) to testicular membranes was highly specific and saturable. Uptake of labelled gonadotropins was proportional to the amount of membrane protein, with 125I-oFSH showing greater specific binding. Initial association of 125I-oLH with binding sites was comparable at 4, 25, and 34 degrees C; with prolonged incubation, maximal binding occurred at 4 degrees C. Equilibrium was achieved in 8 h at 34 degrees C and in 16 h at 25 and 4 degrees C. In contrast, the temperature-dependent association of LH with rat testicular membranes was greater at 25 than at 4 degrees C. The rate of association of 125I-oFSH to binding sites was proportional to incubation temperature, with equilibrium being achieved in 2 h at 34 degrees C and in 16 h at 25 degrees C; binding at 4 degrees C; was slow and still increasing by 48 h. Binding of radioactive and nonradioactive oLH and oFSH was hormone specific and increased in a dose-dependent manner until saturation occurred. Shortening the scrotum of adult rams led to reductions (p less than 0.05) in testicular weight (60%) and in the number of LH (55%) and FSH (90%) binding sites per testis, with no apparent change in serum testosterone concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Some aspects of cattle behaviour in extensive systems

In beef cattle, a difference is usually made between the cow/calf herd and the fattening herd. While the cow/calf herd roams over a large area of grassland, the fattening herd is usually concentrated on better grazing camps in summer and in feedlots during the fattening period of 90-120 days, which could be either in winter or in summer. High libido is needed under South African circumstances when bulls have to serve many cows in a short period, or when these bulls have large areas over which to range. Libido and fertility may not be related, and great differences have been encountered between Bos taurus and Bos indicus bulls. The results presented are from ethological studies on a Drakensberger herd over a period of 4 years, and show a clearly established dominance order. For fattening, most of the male avimAls are castrated. They can then be handled more easily and are generally free from behaviour problems, although riding occurs under stress situations, especially in crowded feedlots. Partial castrates short scrotum castration can be useful. Although all male hormone levels are reduced, there is no evidence for decreased aggression or the abovementioned riding problem. Research both ethological and engineering has been carried out in order to find the ideal handling facilities for the beef farm in extensive areas. It has become essential that veterinarians should be involved in the planning and building of these facilities. Many aspects have to be taken into consideration, such as the hot summer sun, the sudden heavy rain showers in the rainy season, the dust in the dry season, and the overcrowding of wild or semi-wild animals. Several of the facilities must be regarded as essential, other as optional. Financial expenses must be covered by the saving of labour.

Mating behavior, serum testosterone and semen characteristics in vasectomized and short scrotum rams

Ten similar rams were either vasectomized (VAS) or altered by securing the testes near the abdomen using elastrator bands (short scrotum, SS). Semen characteristics (electroejaculation) were similar (P>0.10) between groups before treatment and ejaculate volumes remained relatively constant (P>0.10) throughout the trial. Remaining sperm cells were nonmotile and 95% abnormal by 6 days after vasectomy. By 12 days after surgery, ejaculates contained no cells. Two SS rams had detectable sperm numbers at 12 days after treatment, but 95% were abnormal and all but 1% were nonmotile. Ejaculates collected 3 months after surgery were similar between treatments, in that all existing cells were nonmotile and abnormal. Partial spermatogenic function was regained in SS rams 15 months after treatment as indicated by the presence of low concentrations of motile sperm. Three and 15 months after treatment, sexual activity was estimated by exposing rams to a group of four estrous ewes. During the 15-minute exposure, VAS males exhibited more (P<0.10) nonmating sexual approaches than did SS animals during the first year. However, nonmating approaches and incomplete and completed matings were similar (P>0.10) between VAS and SS rams during the second year. No treatment differences in serum testosterone were observed before, during or after either libido trial. Shortening the scrotum of 6-month-old ram lambs has little effect on libido or testosterone when compared with VAS rams. However, the SS method of alteration does not result in complete sterility as indicated by the presence of motile spermatozoa in ejaculates 15 months after SS treatment.

Carcass Palatability and Retail Characteristics of Steers and Short Scrotum Bulls

Carcass Palatability and Retail Characteristics of Steers and Short Scrotum Bulls

Luteinizing Hormone, Testosterone, Growth and Carcass Reponses to Sexual Alteration in the Ram1

A total of 130 ram lambs were used in a study to determine the effects of sex alteration on serum hormone levels, growth rate and carcass traits. Sex alteration included no treatment (intact rams), scrotal ablation to alter normal testicular secretion (short scrotum rams) and castration to completely remove influences derived from the testes (wethers). Although these data suggest that scrotal ablation at birth did not produce complete azoospermia in Finn-crossbred rams, reduction (P<.01) in testicular weight did produce significant results. Serum testosterone in short scrotum and intact rams was similar, whereas castration resulted in considerably lower concentrations of this steroid (P<.01). On the other hand, serum luteinizing hormone was increased (P<.01) threefold in short scrotum rams and 12-fold in wethers as compared to that of intact rams. Because these results cannot be fully explained by changes in serum testosterone, it is speculated that changes in secretory products of the testis which accompany degeneration of the germinal epithelium are responsible for elevated luteinizing hormone Post-weaning average daily gain (P<.01) and feed efficiency were highest in intact and short scrotum rams indicating that testosterone (or testis) may be beneficial. Although dressing percentage and adjusted backfat were highest (P<.01) in wethers, carcass weight and yield grade were advantageous (P<.01) in short scrotum and intact rams. Quality grades were similar; all animals reached average choice.

Comparison of Carcasses and Meat from Steers, Short Scrotum Bulls and Intact Bulls

Comparison of Carcasses and Meat from Steers, Short Scrotum Bulls and Intact Bulls

Live and Carcass Characteristics of Holstein Castrated, Short Scrotum and Intact Males

Thirty male Holstein calves were allotted at an average age of 63 days to three treatments: a) intact bulls; b) shortened scrotums; and c) castrated. An additional 10 calves were used to determine rate of testicle enlargement between 63 and 190 days of age. The three groups of cattle were slaughtered at the same average age of 402 days. Mean growth rates of the steer and short scrotum calves were similar to 190 days of age, but significantly (P< .05) less than that for bulls. From 190 to 402 days of age, there were significant (P< .01) ADG differences between each of the three sex conditions. However, the means for carcass weight/day of steer and short scrotum cattle did not differ significantly, and both were less (P< .01) than the corresponding means for bulls. Mean testicle weight of bulls was twice the mean testicle weight of short scrotum cattle at slaughter. The means for characteristics measuring carcass cutability were similar for bull and short scrotum cattle, with steer carcasses generally having more itermuscular fat and smaller longissimus muscle areas. Means for organoleptic characters were similar or more desirable for bull carcasses. These results indicate that there is little to be gained by using the short scrotum procedure.

Effects of sex alteration, breed, type of rearing and creep feeding on lamb growth.

Eight hundred and seventy-three lambs from seven breeds were used in a study to determine the effects of sex alteration, breed, type of rearing and creep feeding on lamb growth. Rams, rams implanted with 3 mg DES and short scrotum lambs had heavier weaning weights and higher weights per day of age at weaning than wethers. Rams implanted with DES were not different from non-implanted intact rams in the growth and carcass traits measured in this study. Significant (P<.001) breed-sex treatment interactions were observed for weight per day of age at slaughter and carcass grade. Intact rams, rams implanted with 3 mg DES and short scrotum rams gained faster than wethers in all breeds except the purebred Targhee and Navajo. With the exception of the higher carcass grade for Coarse Wool ram lambs, wethers and short scrotum males had higher carcass grades than intact rams and rams implanted with DES. Type of rearing had more effect on pre-weaning growth than type of birth, with little compensatory post-weaning growth response to compensate for pre-weaning differences. Creep feeding had no effect on lamb gains, due primarily to the limited feed intake.