Effect of undegradable protein supply on testicular size, spermiogram parameters and sexual behavior of mature Assaf rams

Improved early postnatal nutrition and its effect on histomorphological parameters in the testes of Sanjabi ram lambs

The effect of an ad libitum supplementary feeding on some reproductive characteristics of ram lambs were evaluated. Twelve Sanjabi rams were allocated to one of two groups: control (C) and treatment (T). The control group received hay and the treatment group received hay and concentrate with gross energy and crude protein concentration of 4.52 Mcal and 16% of dry matter, respectively. At the end of experiment, after taking blood samples for determination of testosterone concentration (TC), all lambs were castrated and the testicular weight (TWT), testicular volume (TV), testicular length (TL), and testicular width (TW) were measured. In addition, testes were subjected to histological analysis. Body weight (BW), TC, TWT, TL, and TV in the T group were higher (P < 0.05) than the C group. However, TW was not affected by diet (P > 0.05). Animals from the C group presented lower numbers (P < 0.05) of Sertoli (SCN), germ (GCN), and Leydig cell numbers (LCN) compared to the T group. Also, seminiferous tubule diameter (STD) in the T group was significantly greater than (P < 0.05) the C group. TWT had a significant association with TC (P < 0.05), STD (P < 0.01), SCN (P < 0.01), GCN (P < 0.05), and LCN (P < 0.05). TC was correlated with STD (P < 0.01), SCN (P < 0.01), GCN (P < 0.05), and LCN (P < 0.05). STD showed close correlation with SCN (P < 0.01), GCN (P < 0.01), and LCN (P < 0.05). Also, SCN had a positive association with GCN (P < 0.01) and LCN (P < 0.05). A positive correlation was found between GCN and LCN (P < 0.01). In conclusion, the plane of nutrition of growing ram lambs enhances their growth and testicular development and probably will increases their postpubertal reproductive performance.

Association of MTNR1A and CYP19 genes polymorphisms with sperm quality and testicular size in Sanjabi breed rams

The purpose of this study was to identify mutations in melatonin receptor 1A (MTNR1A) and aromatase cytochrome P450 (CYP19) genes using PCR-RFLP technique and their associations with sperm quality and testicular size traits in Sanjabi breed rams. The blood and sperm samples were collected from Sanjabi rams (n = 96). Genomic DNA was extracted from the blood. A 824bp fragment from exon II of MTNR1A gene and a 517bp fragment from promoter 2 (P2) of CYP19 gene were amplified using two pairs of specific primers. The PCR products were separately digested by two restriction enzymes, SsiI for MTNR1A locus and DraI for CYP19 locus. Digestion by SsiI restriction enzyme resulted in CC, CA and AA genotypes with frequency of 0.45, 0.41 and 0.14, respectively. However, digestion of 517bp fragment of CYP19 gene by DraI endonuclease determined two AG and AA genotypes with frequency 0.89 and 0.11, respectively. The Chi-square test proved that the two loci were in Hardy-Weinberg equilibrium (HWE). The significant effect was observed between different genotypes of MTNR1A gene and morphological trait (P<0.05) and there was a significant association between different genotypes of CYP19 gene and scrotal circumference trait (P<0.05). The results of this study indicated that polymorphisms of MTNR1A and CYP19 genes were not associated with most traits of sperm quality and testicular sizes. Therefore, it seems that further studies are needed to identify mutations in other regions of these genes and other genes responsible to genomic regions for the sperm quality and testicular size in Sanjabi ram in order to improve fertility in these herds.

Effect of increasing levels of wasted date palm in concentrate diet on reproductive performance of Ouled Djellal breeding rams during flushing period

Aim

The aim of the study was to assess the effect of two levels of wasted date (WD) by replacing commercial concentrate on the reproductive performance of Ouled Djellal (OD) rams.

Materials and Methods

Eighteen mature (2-year-old) OD rams were equally allocated to three groups and fed during 11 weeks with one of three different experimental diets, that contained 0% (0 WD), 50% (50 WD), or 75% (75 WD) of WDs in concentrate diet. Live body weight (LBW), body condition scoring (BCS), scrotal circumference (SC), testicular weight (TW), sperm production and quality, plasma testosterone concentration (T), and sexual behavior (reaction time and number of mounts with ejaculation) were regularly recorded from every ram.

Results

LBW, SC, and TW changed significantly among diet groups and during the experimental period (p<0.001), the highest averages were recorded in (0 WD) group. LBW, BCS, SC, TW, semen volume, and percentage of the positive hypo-osmotic swelling test were (p<0.001) positively influenced by flushing period. Nevertheless, sperm concentration showed a significant (p<0.001) decrease at day 30, followed by a return to the initial values afterward. There were no differences (p>0.05) between diet groups for plasma testosterone concentration and semen attributes, except that (50 WD) group expressed the lowest overall value of semen concentration. Furthermore, neither time nor diet affected (p>0.05) sperm motility and reproductive behavior parameters.

Conclusions

It is possible to introduce WD as unconventional local feeding resources in flushing diet of breeding rams without disturbing their reproductive performance.

Cellular and molecular responses of adult testis to changes in nutrition: novel insights from the sheep model

This review explores the cellular and molecular mechanisms that regulate spermatogenesis in the post-pubertal testis that is regressing in response to mild undernutrition, using the sexually mature male sheep as a model. Testis regression leads to reductions in daily sperm production and in the quality of ejaculated spermatozoa (poorer movement, DNA damage). There is also a reduction in spermatogenic efficiency that appears to be caused, at least partially, by increases in germ cell apoptosis. Sertoli cell number does not change with testis regression, although about 1% of Sertoli cells do appear to retain proliferative ability after puberty. On the other hand, Sertoli cell function is disrupted during testis regression, as evidenced by a disorganization of tight junctions and indications that cell differentiation and maturation are reversed. Disrupted Sertoli cell function can explain, at least partially, the increase in germ cell apoptosis and any decrease in the rate of spermatogenesis, the two major contributors to spermatogenic efficiency. These outcomes seem to be mediated by changes in two RNA-based processes: (i) the expression of small non-coding RNAs that are involved in the regulation of Sertoli cell function, spermatogenesis and germ cell apoptosis and (ii) alternative pre-mRNA splicing that affects the regulation of spermatogenesis but does not appear to affect germ cell apoptosis, at least during testis progression induced by undernutrition in the male sheep. These research outcomes can be extended to other animal models and are relevant to issues in human male fertility.

Effect of milk replacer and rumen inert fat on growth and reproduction of Malpura ram lambs

The objective of this study was to assess the effects of milk replacer and rumen inert fat on growth, testicular development, puberty, semen production and sperm motion characteristics of ram lambs reared under intensive management in semi-arid climatic conditions. Seven-day-old male lambs of Malpura breed (n=20) were divided equally into two groups. Up to weaning, the lambs in G1 group (control) were fed concentrate, green khejri (Prosopis cineraria) leaves and cowpea (Vigna unguiculata) hay along with suckling of dams, whereas lambs in G2 group were fed reconstituted milk at 17 g/lamb per day for the 1st week and at 34 g/lamb per day from 2nd week in addition to the feed inputs given in G1. During post weaning, lambs in the G1 group were given control concentrate, whereas in G2 the control concentrate supplemented with 40 g rumen inert fat per kg of feed was offered along with dry pala (Zizyphus nummularia) and ardu (Ailanthus excelsa) leaves. BWs of lambs were recorded weekly up to 6 months of age. Ram lambs of both the groups were trained for semen collection at a weekly interval from the age of 5 months and simultaneously testicular measurements were recorded fortnightly. The feeding of milk replacer and rumen inert fat had positive (P<0.05) effects on BW, testicular length, testicular volume, semen volume, sperm concentration, mass motility, % motility, % rapid, medium or slow motile spermatozoa. However, no significant effect was observed on testicular breadth, scrotal circumference, age of puberty, sperm velocities and other CASA-derived parameters. The results of this study indicate that higher plane of nutrition in the form of milk-replacer feeding during preweaning and rumen inert fat-supplemented feed during the postweaning period to growing ram lambs enhances their growth, testicular development and semen quality.

Carotenoid supplementation during adulthood, but not development, decreases testis size in mallards

Nutritional constraints on reproduction are well-characterized in female animals, but rarely have particular nutrients been linked to male reproductive investments. Carotenoid pigments promote egg-laying and fertility in several animals, and are displayed externally within secondary sex traits by males of many colorful species to attract mates, but it is unclear if or how carotenoids affect male primary sex traits. We manipulated carotenoid availability in the diet of male mallards (Anas platyrhynchos) during both development and adulthood to determine effects on size and carotenoid content of the testes. We found that developmental carotenoid manipulations did not affect testis size or carotenoid concentration, but that increased carotenoid dietary levels at adulthood resulted in more carotenoid-rich, but smaller, testes. This latter result was surprising, given positive correlations in mammals between testicle size and carotenoid concentration. We also found negative correlations between testis size and carotenoid concentration for individual ducks, regardless of dietary treatment. These results suggest that carotenoid deposition into testis tissue can reduce investment in gonad size (and thus overall sperm count), although the functional consequences of this relationship remain to be tested.

Modification of spermatozoa quality in mature small ruminants

This review is based largely, but not entirely, on the assumption that gamete quality is directly linked to sperm output and thus testicular mass, an approach made necessary by the absence of a large body of data on factors that affect gamete quality in ruminants. On the other hand, there is a change in the efficiency of sperm production per gram of testicular tissue when the testis is growing or shrinking, a clear indicator of changes in the rates of cell loss during the process of spermatogenesis, probably through apoptosis. We therefore postulate that the spermatozoa that do survive when the testis is shrinking are of a lower quality than those that are produced when the testis is growing and the rate of sperm survival is increasing. In adult small ruminants in particular, testicular mass and sperm production are highly labile and can be manipulated by management of photoperiod (melatonin), nutrition, genetics and behaviour (‘mating pressure’). Importantly, these factors do not act independently of each other – rather, the outcomes in terms of sperm production are dictated by interactions. It therefore seems likely that spermatozoa quality will be affected by these same factors, but definitive answers await detailed studies.

Long-term effect of nutrition on the metabolic status and reproductive potential of Merino rams under grazing conditions

To evaluate the impact of feeding rams for 14 weeks with legumes and supplement on their clinical, behavioural and endocrine responses, 32 Merino rams, 17 months old, were allocated to four groups (n = 8). The 2 × 2 factorial arrangement evaluated the pasture type (IP, improved pasture; NP, native pasture) and the effect of feeding (+S) or not (–S) feeding a supplement. Every 2 weeks liveweight, scrotal circumference and serving capacity were evaluated and blood samples taken to measure the concentrations of metabolites and metabolic hormones. Grazing behaviour was evaluated every 4 weeks. Rams grazing IP (61.8 ± 0.7 kg) were heavier than those grazing NP (59.6 ± 0.7 kg; P < 0.05), and +S rams (61.8 ± 0.7 kg) heavier than –S rams (59.3 ± 0.6 kg; P < 0.05). Compared with rams from the IP+S, IP–S and NP+S, rams grazing NP–S lost weight (P < 0.001) during the experiment. The scrotal circumference was larger in IP+S (30 ± 0.4 cm), IP–S (30 ± 0.4 cm) and NP+S (31 ± 04 cm) than in NP–S (29 ± 0.4 cm; P < 0.001). Only in rams from the group NP+S was a significant increase in scrotal circumference observed during the trial (P < 0.05). The supplement tended to maintain the mating potential elevated towards the end of the experiment (+S: 74.3 ± 5.4 and –S: 61.7 ± 6.3 ewes/ram; P = 0.07). Supplemented rams were less frequently seen grazing (47 ± 3%) than non-supplemented rams (57 ± 4%; P = 0.09). Rams grazing IP ruminated more frequently (13 ± 2%) than those grazing NP (9 ± 2%; P < 0.001). Events such as lying down, playing, self-grooming and drinking water were more frequent in supplemented (36 ± 2%) than non-supplemented rams (30 ± 2%; P = 0.09). The supplement increased the concentrations of insulin and glucose and decreased the concentrations of non-esterified fatty acids, albumin and urea (P < 0.05). IP increased the concentrations of insulin-like growth factor-I, protein, albumin and urea and tended to increase the concentrations of insulin. We conclude that feeding Merino rams a high plane of nutrition reduced the frequency of grazing events and stimulated a long-term improvement of the metabolic status, evidenced by an increase in liveweight and scrotal circumference, with relevant implications for their mating potential.

Efficiency assessment of a swift method to enhance substandard viability ram ejaculates

Semen availability in ram semen processing facilities is of great importance for the genetic improvement of sheep. Accordingly, any method that would increase sperm viability in low viability ejaculates could be useful. In this study, the possibility of a glass beads filtration method by estimating the beads total surface provided (TSP) for adhesion of spermatozoa, was evaluated. Initially, two different TSP (102 and 154 cm(2)) achieved by various sizes of beads (1500, 2000 and 3000 microm) were tested and no significant difference in sperm viability improvement was noticed for the same TSP by different beads (p > 0.05). Next optimization tests were performed in which three different funnels were used for filtration at a standard TSP (154 cm(2)). The pear-shaped funnel was found to be the most appropriate for filtration, as semen volume recovery and sperm viability improvement were more pronounced (p < 0.05). Finally, filtration tests were conducted with pear-shaped funnels with different TSP (102 and 154 cm(2)) obtained by the aforementioned beads sizes (1500, 2000 and 3000 microm) in equal aliquots. Total surface provided of 102 cm(2) proved to be the more appropriate for filtration than 154 cm(2), as shown by the significant improvement of sperm viability (p < 0.01) and the significantly higher filtrate semen volume (p < 0.05). In conclusion, ram sperm viability improvement by more than 20% of its initial value and semen volume recovery by more than 60%, along with the fact that the total filtration time did not exceed 6 min in any case, suggest that through further development this method could be successfully used during ram semen processing.

Effect of undegradable protein concentration in the post-weaning diet on body growth and reproductive development of Assaf rams

Twenty-four growing Assaf lambs, divided into four groups of six animals, were used to study the effect of the undegradable protein content of the post-weaning diet on feed intake, body growth and reproductive development. From week 1 to week 21, the four groups were fed ad libitum as follows: group LL was given barley straw and low protein concentrate (LP); group HH was given barley straw and high protein concentrate (HP); group LH was given barley straw and LP concentrate from week 1 to 11 (period 1) and barley straw and HP concentrate from week 12 to 21 (period 2); group HL was given barley straw and HP concentrate in period 1 and barley straw and LP concentrate in period 2. From week 22 to week 26 (period 3), all animals received the same amount of hay and LP concentrate. Barley straw intake was not significantly (P>0.05) affected by dietary treatments. In the 1st period, average concentrate intake and live body weight gain (LWG) were greater in lambs fed HP than LP supplement. In the 2nd period, concentrate intake was not significantly (P>0.05) affected by type of supplement, but LWG was greater for lambs fed HP than LP supplement. Scrotal circumference in week 11 was significantly (P<0.05) lower in lambs fed LP supplement than in lambs fed HP supplement. No significant differences (P>0.05) due to dietary treatments were observed on scrotal circumference in weeks 21 and 25. Dietary treatments had no significant (P>0.05) effect on either circulating concentration of testosterone or ejaculate characteristics. In conclusion, results from this study suggest that supplementing diets with undegradable protein enhanced performance throughout the breeding period and accelerated testis growth. Nevertheless, final testis size, pattern of circulating testosterone and sperm output were unaffected by dietary treatments.