Postnatal testicular development in Vietnamese pot-bellied pigs.

The Vietnamese pot-bellied pig is a breed with high investigation potential. However, at the reproductive level, its testicular characteristics are still unknown, as well as the different stages of its development. Therefore, the objective of this work is to describe the postnatal testicular development of Vietnamese pot-bellied pigs. In this study, we used pigs grouped into the neonatal stage, animals at zero weeks; prepubertal stage, animals at three and eight weeks; pubertal stage, animals at twelve and sixteen weeks; and postpubertal stage animals at twenty, twenty-four, twenty-eight and thirty-two weeks of age. The neonatal stage is characterized by gonocytes at different migration phases. In the prepubertal stage, gonocytes were differentiated into spermatogonia at 3 weeks of age, and the first spermatocytes were observed at 7 weeks of age. Puberty was determined to start at 12 weeks because seminiferous tubules are found with complete spermatogenesis and the highest peaks in positive cell counting of androgen receptors (AR) and proliferating cell nuclear antigen (PCNA) factor that later decreased and further stabilized in the following weeks. In the postpubertal stage, an increase in seminiferous tubule areas was observed. The number of apoptotic cells ranged from low to null at all ages. Testosterone (T) and gonadotropin levels had two important peaks at 3 and 24 weeks. The seminiferous epithelium cycle was found to have 11 stages according to acrosome development. These characteristics of Vietnamese pot-bellied pig testes, which are different from rat testes and more similar to human testicles, make them a viable model to study human male reproductive biology. The postnatal testicular development of pot-bellied pigs is different from the postnatal testicular development of other breeds. Therefore, due to this difference in size and easy manipulation, the Vietnamese pig is an alternative for investigation compared to other pig breeds.

The role of scrotal ultrasonography from infancy to puberty.

BACKGROUND: Scrotal ultrasonography is an essential diagnostic tool in daily clinical practice. The availability of new-generation ultrasound machines characterized by clearly improved image quality, low health cost, and higher patient safety, represents only some characteristics of ultrasound investigation. The usefulness of scrotal ultrasonography is particularly evident in the period of life from infancy to puberty, during which males undergo important morphofunctional changes, and several pathological conditions may occur. OBJECTIVES: This pictorial review primarily aimed to investigate the aspects of ultrasonography related to the normal physiological development of the gonads from mini-puberty to pubertal onset. This study also aimed to provide an update on the use of ultrasonography in main andrological pathologies that may occur during this period. The conditions that are discussed in depth are: cryptorchidism, inguinoscrotal hernias, and hydrocele in the neonatal phase; acute scrotum, epididymo-orchitis, and testicular cancers in childhood; and hypogonadism, varicoceles, testicular microlithiasis, and oncohematological pathology in puberty. DISCUSSION: We provided an ultrasound slant for all the above-mentioned pathologies while purposely avoiding excessive deepening of the pathogenetic, clinical, and therapeutic aspects. Studying the ultrasound aspects of the gonads also facilitates differential diagnosis between various conditions and represents a good aid in evaluating therapeutic success (e.g., in hypogonadism or postsurgical evaluation of varicoceles and cryptorchidism). CONCLUSION: Scrotal ultrasonography is now globally recognized as the necessary completion of clinical-laboratory overview in gonads evaluation. This diagnostic procedure is even more indispensable in the infancy-childhood-puberty period for the evaluation of normal gonadal development as well as diagnosis of other possible diseases.

Evaluation and prediction of scrotal circumference in beef bulls.

Scrotal circumference (SC) is considered a useful tool for predicting age at puberty and is performed to improve the reproductive performance in beef cattle industry. We aimed to fit several nonlinear mixed models for SC measurements of five different breeds to better predict testicular growth. Data of SC (cm), body weight (BW; kg), and age (A; days), farm location, sire and dam, and birth dates of 169,094 beef bulls were collected from five breeds: Nelore (N) (n = 110,814); Angus (AA) (n = 6541); Brangus (BA) (n = 42,910); Polled Hereford and Hereford (HH) (n = 4640); and Braford (BH) (n = 7480). Data comprise a total of 8640 sires and 115,172 dams and grouped in 2908 contemporary groups (CG). The full model development for SC was defined as: SC = CG + A + A*A + BW + BW*BW + Æ. Bulls from HH (34.1 ± 3.2) and AA (33.5 ± 3.0) had the highest value of SC, followed by BH (32.2 ± 3.7), BA (30.6 ± 4.1), and N (26.9 ± 3.6). There was a curvilinear effect of BW on the SC measurements of HH and AA bulls, reaching the maximum point around 600 kg, whether both breeds presented a similar testicular growth pattern. In British breeds, inflection points of average daily SC growth of 0.039 and 0.042 cm/kg were obtained from 700 kg HH and 600 kg AA bulls, respectively. Scrotal circumference values of 0.042 and 0.046 cm/kg reaching the maximum growth point at 450 kg BW were obtained for BH and BA bulls, respectively. We also observed SC values of 0.044 and 0.048 cm/d reaching the maximum growth point at 550 d of age for BH and BA bulls, respectively. Thus, estimate testicular size at maturity should be measured between 500 and 600 kg BW in British genotypes and between 550 and 600 d in Bos indicus and crossbreeds animals. Therefore, SC adjustment can be used by breed-specific criteria associated with BW and/or age to determine testis growth as a selection criterion in beef cattle breeding programs.

Productive performance and reproductive characteristics of Morada Nova male lambs fed with high-energy diet.

Morada Nova breed sheep are without wool, tropicalized, small-sized animals, known for their high-quality meat and skin. Their body development naturally depends on the genetic potential and adequate nutritional support, which suggests that the offer of high-energy density diets positively influences their productive indicators. Thus, the present study investigated the effect of a high-energy diet for the Morada Nova lambs on body development and testicular function, considering their histomorphometric characteristics and seminal quality. Forty-two males (19.2 weeks, 20.7 ± 3.5 kg) were equally divided into two groups and fed with 2.05 Mcal (G7, n = 21) or 2.37 Mcal (G24, n = 21) of metabolizable energy/day, equivalent to 7% and 24% above the minimum for growing lambs. The animals were confined for 23 weeks (W0 to W23). Weight and body score differed significantly from the W1 (P < 0.05). From the W5, thoracic perimeter, body length, wither height, and rump attributes were higher in G24 (P < 0.05). The scrotal circumference and testicular volume were higher in G24 from the W3 (P < 0.05). Although testosterone levels were not affected (P = 0.05), the highest energy intake increased the diameter of the seminiferous tubules and the development of the epididymal epithelium (P < 0.05). This positively influenced the seminal quality and reduced the minor defects (21.87% vs. 17.13%) and the total spermatic defects (26.34% vs. 21.78%, P < 0.05). Thus, it is possible to employ higher levels of dietary energy for Morada Nova young males to express higher productive efficiency and earlier reproductive attributes of interest.

Extending the interval between second vaccination and slaughter: I. Effects on growth, scrotal size and stress responses of immunocastrated ram lambs.

Immunocastration provides a less invasive means of castrating lambs. Considering increasing consumer awareness, the efficacy of this technique on commercial slaughter lambs needs to be further investigated and its effects on growth and stress responses need to be established. This study compared the growth rate, testes size and stress responses of immunocastrated lambs with that of lambs physically castrated with a Burdizzo clamp, as well as intact rams. A total of 40 Dohne Merino ram lambs (average live weight = 45.4±3.68 kg) were randomly allocated to the following four treatment groups: control (intact; R), Burdizzo-castrated (on day 2; B), immunocastrated with a 4-week (ICS4), or a 6-week (ICS6) interval between the second immunocastration vaccination and slaughter. Within the immunocastration treatments, the reaction to vaccination was assessed through injection site scoring, recording the local injection site surface temperature and assigning a walking score. The response to Burdizzo castration was assessed by scoring the reaction during the procedure, testes palpation reaction, walking gait and measuring testis temperature. Additional parameters recorded included BW, serum cortisol concentration, scrotal circumference and rectal temperature. Pain behaviours were described for the short-, medium- and long-term effects after the two methods of castration. Predominantly, tissue-hardening and bruising occurred at the injection sites of immunocastrates, but little effect was observed on walking comfort and no effect on injection site temperature or rectal temperatures. After Burdizzo castration, lambs spent more time in abnormal postures, and from day 3 (D3) to D8 of the trial, discomfort was observed during testes palpation and walking in B lambs. Serum cortisol concentrations were elevated in B lambs on D3 and D15, indicating physiological stress. Thus, immunocastration improved the welfare of castrated lambs as assessed by cortisol secretion, scrotal swelling and pain behaviours, without influencing growth rate.

Effects of androgen and oestrogen on IGF pathways controlling phallus growth.

The development of the mammalian phallus involves hormone-dependent mesenchymal-epithelial signalling mechanisms that contribute to urethral closure and regulation of phallus elongation and growth. In marsupials, most differentiation and growth of the phallus occurs post-natally, making them amenable to direct hormone treatment. Expression of IGFs, FGFs, EFNB2, MAFB, DLX5 and AP-1 mRNAs in the phallus at day 50 post-partum (pp) were altered after treatment of tammar wallaby young from day 20 to 40 pp with androgen, oestrogen or after castration at day 25 pp. However, the most interesting changes occurred in the IGF pathway genes. Androgen treatment upregulated IGF1 in female phalluses and oestrogen treatment upregulated IGF1 in male phalluses, but it was downregulated by castration. IGFBP3 was higher in female phalluses and downregulated by androgen. IGF1 expression was higher in all untreated male than in female phalluses from day 50 to 150 pp, but IGFBP3 had the reverse pattern. At day 90 pp, when urethral closure in males is progressing and male phallus growth is accelerating. IGF1 and PCNA protein were only detected in the male urorectal septum, suggesting for the first time that closure and elongation may involve IGF1 activation of cell proliferation specifically in male phalluses. These effects of sex steroids on gene expression and on the IGF1 signalling pathway in particular, suggest that the developing phallus may be especially susceptible to perturbation by exogenous hormones.

Relationships of plasma insulin-like peptide 3, testosterone, inhibin, and insulin-like growth factor-I concentrations with scrotal circumference and testicular weight in Japanese Black beef bull calves.

This study was conducted to clarify the relationships of plasma concentrations of insulin-like peptide 3 (INSL3), testosterone, inhibin, and insulin-like growth factor-I (IGF-I) with scrotal circumference and testicular weight in Japanese Black beef bull calves (n = 20), from birth to pre-puberty. Monthly blood sampling (0 to 7 months) and scrotal circumference measurements (0 to 7 months) were performed. Testicular weight was recorded immediately after castration at 7 months. Plasma INSL3, testosterone, inhibin, and IGF-I concentrations were measured either by enzyme immunoassay or time-resolved fluorescence immunoassay. The correlation coefficients of these hormonal concentrations with scrotal circumference were significant (P < 0.0001) and it was higher for INSL3 (r = 0.647) than for testosterone (r = 0.597), IGF-I (r = 0.400), and inhibin (r = -0.453). Calves with heavier testes (> 60 g) at castration (7 months) had higher (P < 0.05) plasma INSL3 (from 3 to 7 months) and inhibin (from 1 to 4 months) concentrations than those with lighter testes (< 60 g). The calves with heavier testes at castration had larger (P < 0.05) scrotal circumference than those with lighter testes from 3 to 7 months. In conclusion, blood INSL3 concentrations may be the best functional indicator among the hormones analyzed for determining total testicular volume during pre-puberty in bull calves. In addition, inhibin and INSL3 concentrations in early calfhood may be functional predictors for testicular weight at pre-puberty.

Plasma IGF-I, INSL3, testosterone, inhibin concentrations and scrotal circumferences surrounding puberty in Japanese Black beef bulls with normal and abnormal semen.

The relationships between semen abnormalities and peripheral concentrations of testicular and metabolic hormones in beef bulls are unclear. Here we compared plasma insulin-like growth factor I (IGF-I), insulin-like peptide 3 (INSL3), testosterone, inhibin concentrations, and scrotal circumferences surrounding puberty in Japanese Black beef bulls (n = 66) with normal or abnormal semen. We collected blood samples and measured scrotal circumferences monthly from 4 to 24 months of age. Semen was collected weekly from 12 months until at least 18 months of age. Fresh semen was evaluated for semen volume, sperm motility, concentrations, and morphological defects. The normal fresh semen was frozen by a standard method and examined for post-thaw sperm motility and fertility. Bulls were classified as having either normal post-thaw semen (n = 45) or abnormal semen (n = 21, when at least one of the above test items was abnormal for 6 months). Abnormal semen was classified into abnormal fresh or low-fertility post-thaw which evaluated for rates of transferable embryos. The abnormal fresh was categorized as having sperm morphological defects, low motility, and morphological defects plus low motility. Scrotal circumferences were smaller for the abnormal-semen group vs. the normal-semen group at 20 and 24 months (p < 0.05). Plasma IGF-I, INSL3, and inhibin concentrations in the abnormal-semen group were lower than those of the normal-semen group (p < 0.05) surrounding puberty (4-6, 8, 18-22, and 24 months for IGF-I; 6, 9, 11-14, 17, and 20-21 months for INSL3; 5, 8-13, 16, 17, 19, and 20 months for inhibin). The plasma testosterone concentrations were lower in the abnormal-semen bulls vs. normal-semen bulls only at 22 months (p < 0.05). Analyses of the classified abnormal semen showed lower plasma INSL3 concentrations for morphological defects plus low motility in fresh semen (p < 0.05) and lower IGF-I and inhibin concentrations for low-fertility post-thaw semen (p < 0.05) compared to the normal semen. Our results suggest that reduced secretions of IGF-I, INSL3, and inhibin surrounding puberty may be associated with semen aberration in beef bulls. Notably, the combined sperm abnormality of morphological defects and low motility in fresh semen could involve lowered INSL3, whereas the low-fertility post-thaw semen might be related to decreases of IGF-I and/or inhibin. Pre-puberty blood IGF-I, INSL3 and inhibin concentrations could be used as indicators to predict aberrant semen in beef bulls.

Impact of a timed-release FSH treatment from 2 to 6 months of age in bulls I: Endocrine and testicular development of beef bulls.

In prepubertal males, FSH facilitates Sertoli cell proliferation and testis maturation. The study aimed to determine the effect of an exogenous FSH treatment on hormone secretion and testis development in Angus bulls. Bulls (n = 22) weaned at 53 ± 3.8 days of age were randomized into two treatment groups based on age and pedigree. Beginning at Day 59, bulls were injected im every 3.5 days with either 30 mg FSH (Folltropin-V; NIH-FSH-P1 units) in a 2% hyaluronan solution (FSH-HA, n = 11) or saline (control, n = 11) until Day 167.5. Blood samples to assess FSH, activin A, and testosterone were collected prior to each treatment. To determine how FSH profiles surrounding treatment were affected, three intensive blood sampling periods, each encompassing two treatment administrations, began at Day 66, 108, and 157, and blood was collected at 0, 6, 12, 18, 24, 36, 60, and 84 h respective to time of treatment. Scrotal circumference (SC) and BW were measured monthly. Bulls were castrated at Day 170 to measure testis size, seminiferous tubule diameter, and the number of Sertoli and germ cells per tubule cross-section. During intensive FSH sampling, FSH-HA bulls experienced an increase (P < 0.05) in FSH over control bulls for at least 18 h post-injection in all instances. In blood collected every 3.5 days, FSH concentrations in FSH-HA bulls were increased (P < 0.05) over initial Day 59 concentration from Day 97.5-167.5. FSH concentrations did not differ between treatments from Day 59-90.5, but were greater (P < 0.05) in FSH-HA from Day 94-167.5. Concentrations of activin A assessed for Day 59, 83.5, 94, 129, and 167.5 were greater (P < 0.05) in FSH-HA than control bulls on Day 83.5 and 94. The treatments did not differ (P > 0.1) in testosterone, BW, SC, testis size, tubule diameter, or number of germ cells per tubule. However, the number of Sertoli cells per tubule was greater in FSH-HA than control bulls (45.2 ± 1.4 vs. 41.6 ± 0.9 cells, P < 0.05). In summary, FSH-HA treatment every 3.5 days from Day 59-167.5 maintained elevated FSH for a minimum of 18 h post-injection, likely attributable to the addition of HA. We propose the exogenous FSH-HA treatment initiates a positive feedback loop that includes an increased density of Sertoli cells per tubule cross-section, which is related to increased activin A concentrations on Day 83.5 and 94. Furthermore, this activin A increase preceded an increase in endogenous FSH from Day 94-167.5 in FSH-HA bulls.

Multiple-trait genomewide mapping and gene network analysis for scrotal circumference growth curves in Brahman cattle.

Fertility traits are economically important in cattle breeding programs. Scrotal circumference (SC) measures are repeatable, easily obtained, highly heritable, and positively correlated with female fertility traits and sperm quality traits in males. A useful approach to summarize SC measures over time is using nonlinear models, which summarize specific measures of SC in a few parameters with biological interpretation. This approach facilitates the selection of bulls with larger SC and maturity index (K), that is, early maturing animals. Because SC is a sex-limited trait, identifying the underlying genomics of growth curve parameters will allow selection across both males and females. We reported the first multitrait genomewide association study (GWAS) of estimated growth curve parameters for SC data in Brahman cattle. Five widely used nonlinear models were tested to fit a total of 3,612 SC records, measured at 6, 12, 18, and 24 mo of age. The von Bertalanffy model, individually fitted for each animal, best fit this SC data. Parameter estimates SC at maturity (A) and K as well as SC at all ages were jointly analyzed in a GWAS to identify 1-Mb regions most strongly associated with each trait. Heritabilities were 0.25 for K and 0.32 for A and ranged from 0.51 to 0.72 for SC at 6 (SC6), 12 (SC12), 18 (SC18), and 24 mo of age (SC24). An overlapping window on chromosome 14 explaining around 0.8% of genetic variance for K, SC12, SC18, and SC24 was observed. The major positional candidate genes within 1 Mb upstream and downstream of this overlapping window were , , , and . Windows of 1 Mb explaining more than 0.4% of each trait on chromosomes 1, 3, 6, 7, 14, 17, 18, 24, 25, and 26 were identified. Pathways and net-work analyses were indicated through transcription factors playing a role on fertility traits: , , , , , , and . Further validation studies on larger populations or other breeds are required to validate these findings and to improve our understanding of the biology and complex genetic architecture of traits associated with scrotal growth and male fertility in cattle.

Impact of a timed-release follicle-stimulating hormone treatment from one to three months of age on endocrine and testicular development of prepubertal bulls.

In prepubertal bulls, FSH facilitates testis maturation and a transient proliferation of Sertoli cells. Two experiments examined the effects of exogenous FSH on hormone secretion and testis development in Angus bulls. Exogenous FSH treatment consisted of an intramuscular injection (i.m.) of 30 mg FSH (Folltropin-V) in a 2% hyaluronic acid solution (FSH-HA). In Exp. 1, bulls (50 ± 6.5 d of age) received either FSH-HA ( = 5) or saline (control; = 5) on d 50 and 53.5. Blood samples were collected via jugular venipuncture to assess FSH concentrations every 6 h for 24 h after treatment and every 12 h until 84 h. After each treatment, peripheral FSH concentrations were greater ( < 0.05) in the FSH-HA-treated bulls than in the control bulls 6 h after treatment and tended to be greater ( ≤ 0.08) 12 h after treatment. The FSH concentration from 18 to 84 h after treatment did not differ between treatments. In Exp. 2, bulls were treated with FSH-HA ( = 11) or saline (control; = 11) every 3.5 d from 35 to 91 ± 2 d of age. Blood samples were collected before each treatment to quantify FSH, testosterone, and activin A concentrations. Scrotal circumference (SC) and BW were measured weekly. Bulls were castrated at 93 ± 2 d of age. Seminiferous tubule diameter, testis composition, and the number of Sertoli cells per tubule cross section (GATA-4 positive staining) were determined from fixed and stained histological sections. Follicle-stimulating hormone concentrations within the FSH-HA-treated bulls increased ( < 0.05) on d 70 from prior sampling and remained elevated. The FSH concentration did not differ between treatments from 35 to 66.5 d of age but were greater ( < 0.05) in the FSH-HA-treated bulls than in the control bulls from 70 to 91 d of age. Serum concentration of activin A on d 35, 70, and 91 did not differ between treatments. The FSH-HA and control bulls did not differ ( > 0.1) in BW, SC, testis weight, testis volume, percent of parenchyma composed of tubules, tubule diameter, and concentration of testosterone. The number of Sertoli cells per tubule cross section was greater in the FSH-HA-treated bulls than in the control bulls (33.35 ± 0.9 vs. 28.27 ± 0.9 cells; ˂ 0.05). In summary, the FSH-HA treatment from 35 to 91 d of age resulted in increased endogenous FSH from 70 to 91 d and increased numbers of Sertoli cells at 93 d of age. Exogenous FSH altered endocrine mechanisms regulating endogenous FSH secretion and augmented Sertoli cell proliferation in young bulls, but this effect was apparently not caused by increased activin A concentration in the FSH-HA-treated bulls.

Parameter estimates for reproductive and carcass traits in Nelore beef cattle.

The aim of this study was to estimate genetic parameters for scrotal circumference at 365 (SC365) and 450 (SC450) days of age, age at first calving (AFC), ribeye area (REA), backfat (BF) thickness, and rump fat (RF) thickness, in order to provide information on potential traits for Nelore cattle breeding program. Genetic parameters were estimated using the Average Information Restricted Maximum Likelihood method in single- and multitrait analyses. Four different animal models were tested for SC365, SC450, REA, BF, and RF in single-trait analyses. For SC365 and SC450, the maternal genetic effect was statistically significant (P < 0.01) and was included for multitrait analyses. The direct heritability estimates for SC365, SC450, AFC, REA, BF, and RF were equal to 0.31, 0.38, 0.24, 0.32, 0.16, and 0.19, respectively. Maternal heritability for SC365 and SC450 was equal to 0.06 and 0.08, respectively. The highest genetic correlations were found among the scrotal circumferences. Testing for the inclusion of maternal effects in genetic parameters estimation for scrotal circumference should be evaluated in the Nelore breeding program, mostly for correctly ranking the animal's estimated breeding values. Similar heritability estimates were observed for scrotal circumference, as well as favorable genetic correlations of this trait with AFC and carcass traits. Thus, scrotal circumference measured at 365 days of age could be a target trait for consideration in the Nelore selection index in order to improve most of the traits herein analyzed.

Selection of performance-tested young bulls and indirect responses in commercial beef cattle herds on pasture and in feedlots.

BACKGROUND: Central testing is used to select young bulls which are likely to contribute to increased net income of the commercial beef cattle herd. We present genetic parameters for growth and reproductive traits on performance-tested young bulls and commercial animals that are raised on pasture and in feedlots. METHODS: Records on young bulls and heifers in performance tests or commercial herds were used. Genetic parameters for growth and reproductive traits were estimated. Correlated responses for commercial animals when selection was applied on performance-tested young bulls were computed. RESULTS: The 90% highest posterior density (HPD90) intervals for heritabilities of final weight (FW), average daily gain (ADG) and scrotal circumference (SC) ranged from 0.41 to 0.49, 0.23 to 0.30 and 0.47 to 0.57, respectively, for performance-tested young bulls on pasture, from 0.45 to 0.60, 0.20 to 0.32 and 0.56 to 0.70, respectively, for performance-tested young bulls in feedlots, from 0.29 to 0.33, 0.14 to 0.18 and 0.35 to 0.45, respectively, for commercial animals on pasture, and from 0.24 to 0.44, 0.13 to 0.24 and 0.35 to 0.57 respectively, for commercial animals in feedlots. The HPD90 intervals for genetic correlations of FW, ADG and SC in performance-tested young bulls on pasture (feedlots) with FW, ADG and SC in commercial animals on pasture (feedlots) ranged from 0.86 to 0.96 (0.83 to 0.94), 0.78 to 0.90 (0.40 to 0.79) and from 0.92 to 0.97 (0.50 to 0.83), respectively. Age at first calving was genetically related to ADG (HPD90 interval = -0.48 to -0.06) and SC (HPD90 interval = -0.41 to -0.05) for performance-tested young bulls on pasture, however it was not related to ADG (HPD90 interval = -0.29 to 0.10) and SC (HPD90 interval = -0.35 to 0.13) for performance-tested young bulls in feedlots. CONCLUSIONS: Heritabilities for growth and SC are higher for performance-tested young bulls than for commercial animals. Evaluating and selecting for increased growth and SC on performance-tested young bulls is efficient to improve growth, SC and age at first calving in commercial animals. Evaluating and selecting performance-tested young bulls is more efficient for young bulls on pasture than in feedlots.

Impact of heat stress, nutritional restriction and combined stresses (heat and nutritional) on growth and reproductive performance of Malpura rams under semi-arid tropical environment.

A study was conducted to assess the combined effect of heat stress and nutritional restriction on growth and reproductive performances in Malpura rams. Twenty-eight adult Malpura rams (average body weight (BW) 66.0 kg) were used in this study. The rams were divided into four groups: CON (n = 7; control), HES (n = 7; heat stress), NUS (n = 7; nutritional stress) and COS (n = 7; combined stress). The study was conducted for a period of 2 months. CON and HES rams had ad libitum access to their feed while NUS and COS rams were under restricted feed (30% intake of CON rams) to induce nutritional stress. The HES and COS rams were kept in climatic chamber at 42 °C and 55% relative humidity for 6 h a day between 10 : 00 h and 16 : 00 h to induce heat stress. Body weight increased significantly (p < 0.05) in CON as compared to NUS and COS. When compared within groups, scrotal width morning, scrotal width afternoon, scrotal circumference morning and scrotal circumference afternoon were significantly (p < 0.05) larger in CON while smaller in COS rams. The higher testicular length was recorded both during morning (p < 0.05) and afternoon (p < 0.01) in COS rams while the lowest in NUS rams. The highest plasma testosterone concentration was recorded in CON and lowest in COS rams. Semen volume and mass motility also differed significantly (p < 0.05) between the groups. The highest semen volume and mass motility was recorded in CON and NUS while lowest in both HES and COS rams. It can be concluded from this study that when two stressors occur simultaneously, they may have severe impact on reproductive performance of rams.

Genotype × environment interaction for age at first calving, scrotal circumference, and yearling weight in Nellore cattle using reaction norms in multitrait random regression models.

The aim of this study was to evaluate the effect of genotype × environment interaction (G×E) on age at first calving (AFC), scrotal circumference (SC), and yearling weight (YW) and to estimate genetic correlations between these traits in Nellore cattle using reaction norms in multitrait random regression models. In this study, 28,871, 41,386, and 89,152 records of Nellore cattle for AFC, SC, and YW, respectively, were used. The data were obtained from farms located in the north, northeast, midwest, and southeast regions of Brazil that participate in the DeltaGen Breeding Program. Environmental levels were defined as a function of contemporary groups, that is, animals born in the same herd and year, from the same management group (from birth to yearling), and of the same sex. Postweaning weight gain was used as a criterion to evaluate the environmental conditions for all traits. For reaction norm analyses, residual variances were modeled with homogeneous and heterogeneous classes. The model for SC and YW included the fixed effects of contemporary group and age of the animal as a covariate as well as random direct additive genetic and residual effects. The same model, excluding the covariate age of the animal, was used for AFC. The heritability estimates were low to high for AFC (0.09 to 0.50), high for SC (0.51 to 0.67), and moderate to high for YW (0.33 to 0.71). The genetic correlations (within each trait) along the environmental levels varied from -0.27 to 1.0 for AFC, from 0.73 to 1.0 for SC, and from 0.26 to 1.0 for YW. The genetic correlations between different traits in different environments varied from -0.14 to -0.60 between AFC and SC, from -0.05 to -0.32 between AFC and YW, and from -0.05 to 0.72 between YW and SC. The genetic correlations have had different magnitudes for AFC, SC, and YW, which could indicate the presence of G×E. The present results should support researchers and farmers in defining selection criteria to improve growth traits and sexual precocity. Our results suggest that animals for breeding have to be selected in the same environment and management conditions as their progeny will be reared.

Reduced-rank models of growth and reproductive traits in Nelore cattle.

In beef cattle genetic evaluation, principal component models of the additive genetic effect could be used to incorporate several traits in the same analysis, without an important increase in the number of parameters to be estimated. In this study, multitrait (MT) and reduced-rank models were compared for their ability to estimate parameters and predict breeding values for weaning weight, yearling weight, weaning hip height, yearling hip height, weaning to yearling weight gain, scrotal circumference, and age at the first calving. Data obtained were from 74,388 Nelore animals, born to 1441 sires and 28,502 cows. Six analyses were performed using a MT model that incorporated all the traits simultaneously and five reduced-rank models for the genetic additive direct (co)variance matrix, fitting the first one (PC1), two (PC2), three (PC3), four (PC4), and five (PC5) principal components. The model considering the first three principal components (PC3) provided the best fit. Direct and maternal heritability and the respective standard errors obtained from the MT and PC3 models were similar. In general, the PC3 model provided slightly stronger genetic correlations between the traits when compared with those obtained with the MT model. The rank correlations between the breeding values predicted with the MT and PC3 models for the different traits ranged from 0.93 to 0.99. When 2% and 10% of the best sires were selected on the basis of breeding values predicted by the MT model, the degree of concordance with the PC3 model ranged from 86% to 97%. The first three principal components explained most of the genetic variation among animals, suggesting that major changes should not be expected in the sire's classification on the basis of breeding values predicted for growth and reproductive traits. Models of principal components could be used for beef cattle genetic evaluation, especially when considering several economic traits in the same analysis.

Fatores ambientes e estimativas de parâmetros genéticos do perímetro escrotal na raça Nelore / Environmental effects and genetic parameters estimates for scrotal circumference in Nellore cattle

Foram analisadas mensurações de perímetro escrotal (PE) obtidas aos 365 (PE365, n = 8.564), 455 (PE455, n = 7.463) e 550 (PE550, n = 4.447) dias de idade, com o objetivo de estimar parâmetros genéticos e verificar a adequação do ajuste do modelo de análise de PE para os efeitos de peso ou ganho de peso (GP). Os parâmetros foram estimados pelo método da máxima verossimilhança restrita, com o aplicativo MTDFREML, sob modelo animal e com a inclusão de 54.987 animais na matriz de parentesco. A inclusão no modelo dos efeitos de peso e do GP não influenciou os valores de estimativa de herdabilidade (h2) nas três idades. As h2 variaram de 0,50 a 0,59, dependendo do modelo, sem diferenças importantes entre as três idades estudadas. Os resultados indicaram a possibilidade de ganho genético no PE por meio da seleção direta para esta característica. A melhor idade para seleção do PE seria aos 365 dias...

The aims of this study were to estimate genetic parameters for scrotal circumference (SC) at 365 (SC365, n = 8,564), 455 (SC455, n = 7,463) and 550 (SC550, n = 4,447) days of age using different models and to verify the effect of adjustments for body weight and for weight gain (WG) on parameter estimates. Parameters were estimated using the REML methodology (MTDFREML), with an animal model and considering the relationship among 54,987 animals. The adjustment for weight and WG did not influence heritability (h2) estimates for SC at any age. No important difference among h2 estimates for SC in the three ages was observed. The h2 estimates ranged from .50 to .59 depending on the model. Results suggested that selection for SC would be effective. The best age for SC selection would be at 365 days...

Use of weaning management group as a random effect for a more robust estimation of genetic parameters for post-weaning traits in Nellore cattle.

Data from 69,525 animals were used to compare two types of analyses, one of them having the weaning management group (WEMANG) included as an effect in the contemporary group (F_WEMANG) and the other considering the weaning management group as a random effect, not related to the mathematical model (R_WEMANG) for post-weaning traits. The components of (co)variance were estimated for pre-weaning traits (birth weight and weaning weight) and for post-weaning traits [scrotal circumference (SC), weight gain from weaning to 18 months of age (WG) and muscle score (MUSC)] in Nellore cattle, based on a complete animal model. Heritability of SC, WG and MUSC for the F_WEMANG model was equal to 0.46 ± 0.02, 0.38 ± 0.03 and 0.26 ± 0.01, and for the R_WEMANG model it was 0.45 ± 0.02, 0.31 ± 0.03 and 0.25 ± 0.01, respectively. Genetic correlations between all the studied traits varied between 0.07 ± 0.01 and 0.77 ± 0.03 in F_WEMANG and between 0.02 ± 0.01 and 0.76 ± 0.04 in R_WEMANG. The R_ WEMANG model allowed a decrease in the number of contemporary groups as well as an increase in the number of observations per group without significant alterations in heritability coefficients, for the post-weaning traits. Consequently, the analysis became more robust and avoided having contemporary groups with low variability.

Comparison of testicular volume differential calculations in adolescents with varicoceles.

PURPOSE: We aimed to develop a conversion formula between different calculations for testicular volume asymmetry. MATERIALS AND METHODS: Male adolescents with varicoceles who underwent scrotal ultrasound were studied. Two formulas were analyzed: (1) testicular volume differential, TVDiff = (RTV - LTV)/(TTV), and (2) atrophy index, AI = (RTV - LTV)/(RTV). RTV, LTV, and TTV represent the right, left, and total testicular volume. Through transformations and regression a conversion formula between the calculations was derived. RESULTS: Based on 248 ultrasounds, a clear relationship between the two formulas was demonstrated: AI = ln[(1.97 × TVDiff) + 1], (p < 0.0001). CONCLUSIONS: Differential testicular volumes can easily be converted from one formula to another with near-perfect accuracy. The formulas are essentially identical and interchangeable.

Genetic associations among average annual productivity, growth traits, and stayability: a parallel between Nelore and composite beef cattle.

This study was conducted to examine the relationship among average annual productivity of the cow (PRODAM), yearling weight (YW), postweaning BW gain (PWG), scrotal circumference (SC), and stayability in the herd for at least 6 yr (STAY) of Nelore and composite beef cattle. Measurements were taken on animals born between 1980 and 2010 on 70 farms located in 7 Brazilian states. Estimates of heritability and genetic and environmental correlations were obtained by Bayesian approach with 5-trait animal models. Genetic trends were estimated by regressing means of estimated breeding values by year of birth. The heritability estimates were between 0.14 and 0.47. Estimates of genetic correlation among female traits (PRODAM and STAY) and growth traits ranged from -0.02 to 0.30. Estimates of genetic correlations ranged from 0.23 to 0.94 among growth traits indicating that selection for these traits could be successful in tropical breeding programs. Genetic correlations among all traits were favorable and simultaneous selection for growth, productivity, and stayability is therefore possible. Genetic correlation between PRODAM and STAY was 0.99 and 0.85 for Nelore and composite cattle, respectively. Therefore, PRODAM and STAY might be influenced by many of the same genes. The inclusion of PRODAM instead of STAY as a selection criterion seems to be more advantageous for tropical breeding programs because the generation interval required to obtain accurate estimates of genetic merit for PRODAM is shorter. Average annual genetic changes were greater in Nelore than in composite cattle. This was not unexpected because the breeding program of composite cattle included a large number of farms, different production environments, and genetic level of the herds and breeds. Thus, the selection process has become more difficult in this population.