The effect of dietary energy levels on the sexual puberty of ram lambs (original) (raw)
Related papers
Biometry and Testicular Growth Influenced by Nutrition on Prepubertal Pelibuey Lambs
The growth and testicular development was studied in 48 Pelibuey male lambs 76.6±3.0 days of age and 12.7±1.9 kg body weight (BW), two groups were designed (n=24). 1: Intensive rotational grassing (IRG), 2: Intensive rotational grassing plus nutritional supplement (IRGS). BW was recorded every 15 days from 75 days of age to the onset of puberty. The animals grazed on Panicum maximum. IRGS received a concentrate with 15% of protein. The testicular biometry included scrotal circumference (SC) and testicular volume (TV). Blood samples were collected each 15 days from 90 to 190 days of age for evaluate the testosterone concentrations. BW, SC and TV at histological puberty was higher in IRGS than IRG; 22.5±1.5 vs. 16.06±1.5 kg, 22.0±1.0 vs. 12.2±1.5 cm, 60.5±1.7 vs. 12±3.5 cm 3 respectively (P<0.05) with an average age for the two groups of 162±7.0 days. The correlation coefficient (R) was higher (P<0.05) for SC vs BW than age vs BW (0.884 vs 0.816) and the TV vs. BW than TV vs. age (0.849 vs. 0.777) in the IRGS; the IRG showed lower R for the same comparisons (P<0.05). Seminiferous tubules showed lumen by day 142, spermatids and spermatozoids by day 171 for IRGS, meanwhile in the IRG only showed gonocytes and Sertoli cells. Testosterone concentrations reached a peak (2.5 ng/ml) at 168 days of age for the IRGS meanwhile the IRG showed lower levels than 0.05 ng/ml. Testicular development and testosterone concentrations depends more on BW than age; and they are modified by the nutritional management in prepuberal male lambs.
Animal Reproduction Science, 2015
This experiment was conducted to investigate the effect of plane of nutrition on body weight, average daily gain, dry mater intake, semen characteristics, serum testosterone concentration and testicular circumference of Sanjabi ram lambs during the natural breeding season. Sanjabi ram lambs (n = 20) that were 8 months of age were penned under natural photoperiod at latitude 34 º 18´ N for a period of 9 months. The control group (C, n = 10) received a diet consisting of 80% alfalfa and 20% concentrate, providing 2.18 Mcal metabolizable energy and 130.0 g/kg DM crude protein, whereas, treatment group (T, n = 10) was fed with 65% alfalfa and 35% concentrate, providing 2.34 Mcal metabolizable energy and 160.0 g/kg DM crude protein. Body weight, additive daily gain and feed intake in T group were significantly greater than those obtained in C group. Body weight and testicular circumference increased at a steady rate throughout the experiment. All semen variables (except percentage of abnormal sperm and semen pH), serum testosterone concentration and testicular circumference were positively influenced A C C E P T E D M A N U S C R I P T by nutritional state (P < 0.05). Interaction of nutritional state with season was found for semen volume, sperm concentration and abnormal sperm, but there was no interaction on the total sperm, progressive motility, live sperm, semen pH and semen index. It is concluded that the reproductive activity of growing Sanjabi ram lambs is affected by nutritional state. These results also demonstrated a monthly pattern in reproductive characteristices of Sanjabi ram lambs, independent of the nutritional state.
The aim of this study was to investigate the effect of three different dietary energy levels on some blood and seminal plasma constituents and semen quality of Rahmani rams. A total of twelve Rahmani lambs were used during 9 months from January to September 2007. The lambs had an initial weight 30.9±1.03 kg (8-9 months old, pubertal age). The control diet (recommended allowances) was formulated as a metabolisable energy and adjusted fortnightly due to body weight changes according to NRC (1985). The metabolisable energy contents of the control diet was increased by 20 % for the high energy (HE) diet and decreased by 20 % for the low energy (LE) diet. The actual metabolisable energy levels for the control, high and low dietary energy were 2615, 3138 and 2092 kcal ME/kg on DM basis, respectively. Blood samples were collected fortnightly throughout the experimental period, while semen samples were collected twice weekly from each ram for nine weeks (from July to September of the same p...
Animal Reproduction
Thirty healthy Sohagi ram lambs with an average age of 188.6±7.3 days were used to study the effect of pre-pubertal growth rate on some physiological parameters and sexual behavioral patterns at puberty. Ram lambs were divided into three groups (10 animals per each group) according to the previous growth rate until 6 months of age. Groups were marked as fast, medium and slow growing. Animal groups were housed in closed barns with access to an open area. Results showed that age and weight of ram lambs at puberty were significantly affected (P<0.05) by the pre-pubertal growth rate. Ram lambs in the fast growing group were reached to onset puberty firstly at 272.6 days with body weight (BW) 37.1 kg on average then ram lambs in medium group (284.8 days with BW 32.7 kg), while ram lambs in slow growing group were the last (314.1 days with BW 32.5 kg). Blood testosterone concentration at puberty was not significantly different among growing groups (1.494± 0.03 ng/ml on average, ranged from 1.287 to 1.902 ng/ml). Testes measurements from 6 months of age until puberty show that ram lambs in fast growing group had the highest values of testes length, circumference and volume followed by those in medium and slow growing group. Sexual behavioral observation showed that flehmen and mounting behavior were significantly higher for ram lambs in fast growing group (5.63 and 6.75 number/12h) than slow growing group (4.25 and 5.38 number/12h) while in medium growing group were intermediate (4.88 and 5.88 number/12h). From these findings, could be concluded that age, weight and sexual behavioral patterns of Sohagi ram lambs at puberty were affected by pre-pubertal growth rate, and the breeders should strive to achieve good growth rates for their lambs before puberty which led to improving reproductive performance.
Effect of Pre and Post Weaning Diet Quality on Puberty age and Tail Measures in Kurdish Female Lambs
Theriogenology [Working Title]
To determine the value of pre and post weaning nutrition on puberty age, some hormonal concentrations and tail measures in ewe lambs, a total of 40 clinically health Kurdish female lambs (30±8.6 d and weighing 10.2±3.4 kg) were randomly allocated to one of two experimental diets in pre-weaning period: high quality diet (HQD, 2.50 Mcal ME/kg dry matter (DM) and 148 g CP/kg DM) or low quality diet (LQD, 2.02 Mcal ME/kg DM and 87 g CP/kg DM). At weaning, one half of lambs from each group was randomly separated and assigned to HQD or LQD. So there were four treatment groups in post-weaning period: H-H (HQD pre-and post-weaning); H-L (HQD pre-weaning and LQD post-weaning); L-H (LQD preweaning and HQD post-weaning) and L-L (LQD pre and post-weaning, control group). Within the post-weaning, serum progesterone concentrations was greater for ewe lambs fed at H-H group than for other groups (P<0.05). Serum insulin concentration was affected by the diet quality at both periods (P<0.05). Leptin concentration was affected by treatment and ewe lambs of L-H group had higher leptin concentrations (P<0.05). Diet plan in the pre-pubertal period was affected tail measures in 120 and 210 days of ages (P<0.05).
Testicular development in male lambs prenatally exposed to a high-starch diet
Molecular reproduction and development, 2018
Maternal nutrition during critical gestation periods impacts on offspring in later life; effects of high-starch maternal diet on testicular development in lambs were addressed. Dairy ewes were fed diets providing either 27% (Starch, S) or 11% (Fiber, F) of starch from mating to lambing (∼147 days; S147, F147) or for the last 75 days of gestation (S75, F75). Testes of single male lambs were measured and then sampled for histological and gene expression analyses at selected ages. Testicular dimensions and weight were similar among groups, but the total area of seminiferous tubules increased with age and tended to be higher (p = 0.057) in lambs from starch- than fiber-fed ewes. Sertoli and germ cells number increased with age, but was not influenced by maternal diet. Transcript abundances of androgen receptor (AR), insulin-like growth factor 1 (IGF1), and hydroxysteroid (17-beta) dehydrogenase 3 (HSD17B3) was similar between S147 and F147 lambs (p > 0.1). Abundance of luteinizing ho...
Small Ruminant Research, 2001
The aim of the experiment was to determine whether supplementation of the lamb-ewe unit during intra-uterine and postnatal life affects testicular stereology, particularly Sertoli cell numbers, in 120 pregnant Corriedale ewes grazed either native pastures (control group) or improved pastures grain supplement (treated group). Ewes bearing single ram lambs were maintained under the same feeding regime until lambs were castrated (99 days of age). Body weight, testosterone and FSH blood serum levels were recorded at 45, 75 and 99 days of age. Body weight was higher (P`0X01) in the treated group from birth on. Serum testosterone values did not differ between groups. Serum FSH values tended to differ at 45 days of age (P`0X06). Testicular weight and testes histology showed earlier pubertal development and a tendency for higher Sertoli cell numbers in the treated (supplemented) group. This tendency may indicate that extensively reared lambs supplemented during fetal and postnatal life have higher testicular growth and sperm production in later life. #
The mature male sheep: a model to study the effects of nutrition on the reproductive axis
Reproduction (Cambridge, England) Supplement
We have been using the mature male sheep to study the ways in which nutrition affects reproduction, with a focus on the brain-pituitary axis and, in particular, GnRH activity. The sheep model has four major advantages for such studies. First and most obvious is that the animal is large enough to support long periods of frequent serial sampling of peripheral blood, hypophyseal portal blood and cerebrospinal fluid from the cerebral ventricles. Importantly, we can do this with freely moving animals and thus avoid many of the potential complications associated with restraint. The second advantage, particularly relevant to nutrition-reproduction interactions, is the vast history of nutritional research for this species, providing us with techniques (eg, gut cannulation) and an extensive database on the requirements of sheep for energy, protein, and specific dietary components such as amino acids, fatty acids and trace elements. Third, we can use subtle manipulations of the diet that cover the range seen in the real world, where animals (including humans) rarely encounter the uninterrupted, ad libitum food supplies that are normal for laboratory animals. Within this normal range of conditions, we can measure clear reproductive outcomes without resorting to starvation, and we can study both short-and longterm responses. Finally, the sheep model has an intrinsic economic relevance, and findings from sheep are readily transposed to the other agricultural mammals. The sheep model is also relevant to human biology, often directly, but also indirectly because it often leads us to question the significance of findings from studies with rodents. Using the mature male sheep to study the reproductive endocrine responses to acute and chronic changes in diet, we have shown that glucose does not appear to be directly involved, but fatty acids can stimulate GnRH-dependent pathways that initiate changes in testicular function. Our work also suggested that GnRH-independent (perhaps also neuroendocrine) mechanisms may be involved. In the brain, it seems likely that intracerebral insulin and orexin are important mediators of the GnRH response to nutritional changes, but it seems unlikely that leptin plays a role, at least in mature animals.
Nutritional influences on reproduction in mature male sheep and goats
Journal of reproduction and fertility. Supplement, 1995
Changes in the nutrition of mature rams and goat bucks lead to profound responses in testicular size and therefore the rate of production of spermatozoa. These effects are largely due to changes in the size of the seminiferous tubules and in the efficiency of spermatogenesis. With the exception of severe undernutrition, the effects on spermatogenic function are not accompanied by similar changes in endocrine function of the testes, as measured by the production of testosterone or inhibin. In rams, moderate changes in nutrition affect gonadotrophin secretion for only a few weeks, whereas testicular growth is affected for several months. In mature male goats during the non-breeding season, nutrition-induced testicular growth does not seem to be associated with a gonadotrophin response. Such observations have led us to develop the hypothesis that nutrition-driven testicular growth is at least partly independent of changes in gonadotrophin secretion. The energetic components of the diet...