Scrotal Circumference Measurements Research Articles

Determinants of puberty and age of sexual maturity in Nigerian indigenous breeds of male goats

This study was conducted to ascertain the pubertal and sexual maturity characteristics of Nigerian native goat breeds. The research was carried out on three goat breeds; Sahel (SG), Red Sokoto (RSG), and West African Dwarf (WAD) goats. Each breed was represented by eight (8) animals (n=24) and housed in separate pens based on breed type. All bucks were weighed at birth and bi-weekly using digital weighing scales until they reached puberty. Scrotal circumference measurements were taken every two weeks until the end of the study. Semen was collected immediately after preputial separation and all semen samples were labelled and placed in a thermo-flask immediately and subsequently transported to the laboratory for evaluation. The mass motility and the forward motilities of the spermatozoa were observed using a light microscope. The percentage of live, dead, and abnormal sperms were determined after staining with eosin and negrosin stains. The sperm cell concentration was determined by counting spermatozoa with a hemocytometer. Result obtained indicate that at the 14th and 16th weeks of age, the mean scrotal circumference of bucks ranged from 5.14±0.66 cm to 7.06±0.71 cm, 6.32±0.29 cm to 8.05±0.42 cm, and 5.50±0.74 cm to 7.06±0.71 cm in SG, RSG, and WAD bucks, respectively. Puberty in Red Sokoto bucks was achieved at an average age of 14 weeks, with a mean sperm concentration of (116.17±28.47 x 106), progressive sperm motility of (65.00±9.92%), and a mean body weight of 10.17±1.26 kg. Sahelian and WAD bucks reached puberty at the 16th weeks, with sperm concentrations of 106.29±25.18 x 106 and 107.60±19.99 x 106, mean sperm motility of 65.00±9.94% and 76.00±4.8%, and mean body weights of 11.29±1.59 kg and 7.78±0.70 kg, respectively. To summarise, this study revealed that breed, age, scrotal circumference and body weight at puberty played significant roles in determining sperm characteristics and sexual maturity.

Effects of prenatal and postnatal melatonin supplementation on overall performance, male reproductive performance, and testicular hemodynamics in beef cattle.

Melatonin has been documented to alleviate compromised pregnancies and enhance livestock performance traits. The objective of this study was to determine the effect of prenatal and postnatal melatonin supplementation on overall calf performance and dam milking traits in relation to calves, molecular factors involved in growth and metabolism of calves, along with testicular physiology and fertility traits in subsequent bulls. At day 190, 220 and 250 of gestation, dams (n = 60) were administered either 2 subdermal ear melatonin implants (preMEL) or no implants (preCON). After parturition, birth weights were recorded and calves were blocked based on prenatal treatment and sex. Calves received either melatonin implants (posMEL) or none (posCON) on day 0, 30, and 60 of age. At day 60 of lactation, a subset of dams (n= 32) were selected based on age, weight and calf sex for milk collection and analysis. At weaning, (day 210 postnatally) calf weight, morphometric data, liver samples, and loin samples were collected. At 12 months of age, bull (n = 30) scrotal circumference, scrotal temperature, and testicular artery measurements were recorded. Milk yield and fat percent from dams tended to decrease in the preMEL group (P < 0.07) compared with preCON group. Prenatal melatonin administration did not affect (P = 0.95) calf birth weight and similarly calf weaning weight was unaffected (P < 0.10) by prenatal or postnatal melatonin supplementation. Blood analysis demonstrated that plasma concentrations of melatonin were not different (P = 0.12) in dams; however, an increase (P < 0.001) in plasma concentrations of melatonin was observed in posMEL versus posCON calves. A tendency (P < 0.10) for decreased MYF5 and MYOD1 expression in loin muscle was observed in the posMEL calves. Prenatal and postnatal melatonin administration did not affect subsequent bull scrotal measurements or testicular hemodynamics (P ≥ 0.14). Administering supplemental melatonin via implants during the prenatal and postnatal phase did not alter performance characteristics in offspring. In this study, dams were implanted in winter months, whereas calves were implanted in the spring months. Seasonal differences involving photoperiod and ambient temperature might have attributed to a lack of differences in melatonin levels during the prenatal phase. In the postnatal period, the level of developmental plasticity appears to be too low for melatonin properties to be effective.

Effects of whole cottonseed supplementation on performance, semen quality, and manganese superoxide dismutase concentrations in blood and semen of beef bulls

This research aimed to determine the effects of whole cottonseed on performance, semen quality, and manganese superoxide dismutase (MnSOD) concentrations in the blood and semen of beef bulls. In a completely randomized design, 46 (BW = 457 ± 12 kg; 16–18 mo old) Angus bulls were stratified by BW and randomly assigned to 1 of 3 treatments: DD (n = 14, control; 3.18 kg/d dried distillers grain), WD [n = 16; 1.59 kg/d whole cottonseed (0.56 and 0.82% free gossypol in yr 1 and 2, respectively) and 1.59 kg/d dried distillers grain], or WW (n = 16; 3.18 kg/d whole cottonseed). Bulls were weighed and blood and semen were sampled on d 0, 30, and 60. Body weights and morphological characteristics of spermatozoa were measured in both years, and MnSOD concentrations of blood and semen were measured in yr 1. There was a treatment effect for ADG (P = 0.002) as bulls fed WW had a decreased (P < 0.03) ADG compared with bulls fed WD and DD. A time effect was observed for scrotal circumference (P < 0.001). Scrotal circumference measurements increased on d 60 compared with d 0 and 28 (P ≤ 0.02). There was no time main effect for percentage of spermatozoa with other abnormalities (P = 0.87); however, there was a treatment effect (P = 0.04). Bulls in the WW treatment had fewer other abnormalities than bulls in DD (P = 0.01) but were not different than WD (P = 0.27). Whole cottonseed did not affect reproductive parameters measured in this study or blood and semen concentrations of MnSOD. According to these results, WCS supplemented to beef bulls at 0.7% of BW for 60 d may not negatively affect semen quality or MnSOD concentrations in the blood or semen.

Deep learning–based automated measurements of the scrotal circumference of Norwegian Red bulls from 3D images

The main aim of this study was to create an automated method for the measurement of the scrotal circumference (SC) of Norwegian Red bulls using 3D images of the scrotum based on convolutional neural networks. The study population was bull calves recruited for performance testing before the selection of bulls for semen production in the breeding program. Bulls were measured at four different time points: upon arrival in quarantine (Q) and thereafter at approximately 6, 9 and 12 months of age. Both 3D images and manual SC measurements were performed at all time points. In our approach, SC could be calculated without direct contact with the bull, using only 3D images and a simple, user–friendly application into which mentioned images are uploaded. The results show that SC measurements obtained using semantic segmentation are comparable with manual measurements. The mean prediction error was significantly different between age groups Q, 6, 9 and 12, and it was -3.07 cm, -3.02 cm, -1.79 cm and -1.11 cm, respectively. The results show a significant difference in the measurement error of the SC based on the quality of the images. Images were categorised into three quality groups. For good prediction accuracy, we recommend capturing 3D images of quality 2 – full circle from individuals older than 6 months.

Genetic evaluation of the scrotal circumference of beef bulls in the Czech Republic

The objective of the present study was to estimate the genetic parameters for the scrotal circumference of bulls of beef breeds in the Czech Republic. The used database for the years 1996–2020 comprised information on the scrotal circumference measurements from 22 065 bulls of 19 pure breeds and crossbred animals of the Beef Simmental, Charolais, and Hereford breeds. After adjustments, the database contained 16 404 records. To test the influence of systematic fixed effects, the GLM/SAS procedure using the least-squares method was applied. The contemporary group, weight and age of the bulls were included as significant systematic environmental effects (&amp;lt; 0.05). The genetic parameters were determined by a single-trait model using the AIREMLF90 program. The heritability coefficient of the scrotal circumference was 0.27. Environmental correlations of the scrotal circumference with the bull weight were moderate and positive (r = 0.2), but the correlations between the age in days and the scrotal circumference were almost zero (r = 0.03). The results indicate that the scrotal circumference of beef cattle breeds provides sufficiently high genetic variability that can be used to identify individuals with an above-average circumference and, in this way, increase the probability of selection of a young bull with a better reproduction potential.

Libido and Sperm Quality of the Etawah Cross-Breed Fed Urea Moringa Molasses Multinutrient Block Supplement

Moringa leaves contain high and complete nutrients, so they can be used as a constituentfor multi-nutrient blocks to increase libido and sperm quality. This study aimed to evaluate the effect of Moringa leaf flour in a multi-nutrient block on libido and sperm quality of the Etawah Cross-Breed (PE) goats. This study used a two-sample t-test on 8 PE goats aged 18.50±1.00 months, body weight 32±1.49 kg, kept in individual pens for 8 weeks, given the swamp forage ad libitum. A total of 4 animals were supplemented with urea molasses multi-nutrient block (UMMB) as a control, and 4 animals were supplemented with urea moringa molasses multi-nutrient block (UMMMB) as a treatment. Libido and semen quality were measured from week 4 to week 8. Measurement of scrotal circumference and blood sampling were performed at weeks 0, 5, and 8. The concentration of testosterone in plasma was analyzed using the ELISA technique. The measured variables were compared using the independent sample t-test. UMMMB supplementation did not significantly (p&gt;0.05) increase scrotal circumference and testosterone levels. UMMMB supplementation did not significantly (p&gt;0.05) decrease reaction time, but significantly (p&lt;0.05) decrease mount (24.20±4.30 vs 12.93±1.58 min) and ejaculation (25.60±4.11 vs 13.97±2.23 min). UMMMB supplementation did not significantly (p&gt;0.05) increase semen volume and sperm concentration, but significantly (p&lt;0.05) increased total sperm motility (69.67±0.76 vs 74.67±1.46%) and sperm viability (80.37±0.68 vs 86.48±1.74%). It can be concluded that UMMMB supplementation markedly increased libido, total motility, and sperm viability of PE goats.

Evaluation of scrotal circumference and testosterone levels at different ages of Gayo buffalo as local animal genetic resources

The purpose of this study was to evaluate the scrotum circumference and testosterone levels at various ages of the Gayo buffalo. This study involved 10 Gayo buffalo with four different age groups I: (1.0–2.0), II (2.1–3.0), III (3.1–4.0), IV (4.1–5.0). Blood serum sampling, measurement of scrotal circumference, and age were carried out in Central Aceh regency. The analysis of blood serum testosterone levels was carried out in the physiology laboratory of the Faculty of Veterinary Medicine at Universitas Syiah Kuala. Data on testosterone levels, scrotal circumference, and age were analyzed for variance and continued with Duncan’s Multiple Range Test for data with significant differences. Simple regression analysis was used to determine the relationship between scrotal circumference, age, and testosterone levels. The results of the analysis in the age group and the concentration of the hormone testosterone showed significant differences (P <0.05). The age group of 3.1 to 4.0 years was significantly different from the age group of 1.0–2.0, 2.1–3.0 years, and 4.1–5.0 years. The results of the analysis on the scrotal circumference and testosterone concentration showed no significant difference (P>0.05) in various age groups. There was a significant relationship (P<0.05) between the concentration of the testosterone hormone with age and scrotal circumference, with a regression equation Y= 1.009-0.076X1+0.002X2, with a correlation coefficient (r) of 1 and a coefficient of determination (R2) of 1. These results indicated that scrotal circumference and age greatly influenced the concentration of the testosterone hormone of Gayo buffalo. The conclusion was that age affected the scrotal circumference, but it did not affect the concentration of the testosterone hormone. Gayo buffalo aged 3.1–4.0 and 4.1–5.0 years had a stronger correlation than Gayo buffalo aged 1.0–2.0 and 2.1–3.0 years to scrotal circumference and testosterone concentration.

Assessment of the accuracy of testicular dysfunction detection in male donkey (Equus asinus) with the aid of colour‐spectral Doppler in relation to plasma testosterone and serum nitric oxide levels

This study aimed to determine the usefulness of colour and pulsed Doppler modes for the accurate diagnosis of donkeys suffering from subfertility to determine whether testicular vascularity assessment could be an indicator for sperm functionality. The study sample was composed of 10 male donkeys with normospermia (control group) and 10 donkeys with hypospermia. Animals underwent scrotal circumference measurement, testicular Doppler examination, seminal evaluation, blood sampling and hormonal assay. Semen volume and concentration were significantly (p≤.05) lower in the subfertile group (30.25±1.22ml and 89.44±2.55×106 /ml) as compared with the control group (82.76±1.65ml and 452.78±1.25×106 /ml), and total sperm/ejaculation was significantly (p≤.05) higher in the normal donkeys (28.30±2.32×109 /total ejaculated) as compared with the subfertile group. Intratesticular coloured area showed a marked decline in the hypospermic males. There was no significant difference between the two groups in testosterone level, although the normal group showed an increase in nitric oxide metabolites. Both Doppler indices of the three branches of the testicular artery were elevated significantly (p≤.05) in abnormal donkeys, whereas Doppler peak systolic and end-diastolic velocities were increased in the normal group. Male donkeys with subfertility demonstrated lower arterial vascularity parameters in the form of intratesticular coloured area and blood flow rate; therefore, the most optimal parameters for differentiating subfertile hypospermic from normospermic donkeys were found to be the two Doppler indices, velocities parameters, testicular blood flow rate and nitric oxide levels.

SCROTAL AND TESTICULAR DIMENSIONS IN SOME WEST AFRICAN BULLS

A series of studies were conducted to estimate testicular size from scrotal measurement and determine the relationship between testicular size, age and liveweight in some West African bulls. Repeatability estimate for scrotal circumference measurements between technicians was 0.96. scrotal circumference was highly correlated to paired testes weight (r = 0.88) and volume (r = 0.87). Testes weight and volume were reclosely related (r = 0.997) but their ration (g/cc)varied in 30 bulls from 0.962 to 1.119, with a mean and standard deviation of 1.027 + 0.029. The regression equation for estimating tests weight (Y) from scrotal circumference (X) was Y = 506.17 + 27.70X. Significant correlations existed between scrotal circumference and age (r from 0.59 to 0.79) or liveweight (r from 0.62 to 0.83) in N Dama, Bunaji and Sokoto-Gudali bulls. However, examination of the partial correlations showed that most of the age effects were attributable to changes in liveweight. Limited evidence indicate that young Bunaji bulls have larger testis than the other two breeds although they may be overtaken by Sokoto-Gudali bulls after 5 years of age

Relationships between age, body measurements, and testicular measurements in Arabia bucks in Algeria.

Body size and testicular measurements were found to be important parameters for the evaluation of the breeding quality. A study was therefore carried out on Arabia bucks (n = 180) to record normal testicular characteristics and to evaluate the effect of age on body (BCS, BW, WH, CG, AC, CS, and BL) and testicular (SC, TW, EW, TL, TD, and TL) measurements. Animals were classified into three age classes (less than or equal to 12months, from 12 to 24months, and over 24months). The BW, BCS, testicular, and body measurements of the 3rd age group were significantly higher than those of age groups 1 and 2 (p < 0.01). Male age had a significant effect (p < 0.01) on BW, BCS, and body measurements. Indeed, the parameters of the 3rd age group were significantly higher than those of the 1st and 2nd age groups (p < 0.01). The same was true for testicular measurements (SC, TL, TW, EW, and EL) except for testicular diameter (TD) where the results of the first two age groups had no significant difference. The highest correlation coefficients were recorded between BW and all body (r= 0.7-0.9) and testicular traits (r = 0.72-0.85), BCS and body measurements (r = 0.73-0.89), and scrotal circumference and testicular measurements (r = 0.77-0.85). In conclusion, it was found that the use of BCS is readily measurable in live animals and is expected to be the best indicator of testicular and epididymal measurements. These results, particularly the predictive models developed, could be useful in the selection of males for reproduction.

Genetic correlation estimates between age at puberty and growth, reproductive, and carcass traits in young Nelore bulls

The reduction of age at puberty in young bulls is an important issue to reduce the growing phase and promote substantial savings in production cost as well as to reduce the generation interval. This study aims to estimate genetic parameters for age at puberty in males (APM), growth, carcass, and reproductive-related traits in young Nelore bulls. Additionally, the direct and correlated response for growth, reproductive, and carcass traits were also estimated when a selection was applied for APM in such young bulls. APM was determined through evaluations carried out after weaning, using information from andrological clinical examination, ultrasound records, and scrotal circumference measurements. Records from 181,345 Nelore animals born between 2010 to 2017 were used. These animals were calves from 5,257 sires and 50,742 dams, and belonged to 18 farms located in the Midwest, Southeast, Northeast, and North regions of Brazil. The relationship matrix was built using information from 265,813 animals. The covariance components and the genetic parameters for APM, adjusted scrotal circumference at 365 (SC365) and 450 (SC450) days of age, adjusted weight at 210 (W210) and 450 (W450) days of age, age at first calving (AFC), ribeye area (REA), subcutaneous fat thickness (SFT), and rump fat thickness (RFT) were estimated using a linear animal model. A threshold animal model was used for Stayability (STAY) and early heifer pregnancy (PP30) traits. The heritabilities obtained were: 0.30 (APM), 0.33 (SC365), 0.37 (SC450), 0.14 (W210), 0.26 (W450), 0.08 (AFC), 0.29 (PP30), 0.19 (STAY), 0.32 (REA), 0.19 (SFT), and 0.28 (RFT). The genetic correlations estimates between APM and growth, reproductive, and carcass related traits were: -0.39 (SC365), -0.58 (SC450), -0.01 (W210), 0.08 (W450), 0.30 (AFC), -0.24 (PP30), 0.35 (STAY), 0.08 (REA), -0.05 (SFT), and -0.30 (RFT). The APM is a new approach to evaluate early sexual precocity in young bulls, and it would allow better identification of young candidates when compared to those selected based on scrotal circumference measures. Genetic progress is expected for APM in young bulls since it would favor the heifer's sexual precocity together with the dam's longevity without impacting growth and carcass traits. The results of this study encourage the use of male sexual precocity trait assisted by genomic selection to improve the genetic evaluation reliability of young bulls.

Ultrassonografia testicular em touros jovens e correlação com puberdade e produção espermática

O presente trabalho tem por objetivo avaliar a ecogenicidade do parênquima testicular de touros jovens correlacionando com puberdade precoce. O estudo foi desenvolvido com 39 tourinhos puros de origem (PO) da raça Nelore, com idade entre 12 a 18 meses. A coleta foi realizada mensalmente, onde foi registrado peso, medida da circunferência escrotal e ultrassonografia testicular. A coleta do sêmen foi realizada apenas em animais nas faixas etárias de 14, 16 e 18 meses. Os dados coletados foram organizados em planilha do programa Microsoft Office Excel 2010, para posterior analise utilizando-se o programa estatístico Minitab. Os animais foram separados em dois grupos, os que produziram sêmen e os que não produziram e então classificados em precoces, super-precoces e normais, as médias geradas pela anova foram comparadas pelo teste de Tukey. As variáveis foram correlacionadas pelo método de Pearson. A ecogenicidade do parênquima testicular não influenciou na produção espermática e na precocidade. Os animais precoces apresentaram peso e CE superior aos super-precoces e normais. Peso e idade apresentaram alta correlação, não houve correlação entre peso e média da escala de cinza e, circunferência escrotal e média da escala de cinza. Touros com 18 meses apresentaram percentual de defeitos total inferior a 30%. realização da ultrassonografia testicular não é adequada como indicador de precocidade sexual e produção espermática. A aferição do peso corporal e circunferência escrotal são ferramentas mais eficazes para predizer o potencial reprodutivo de touros Nelore (PO) jovens, sendo estas também, ferramentas de seleção economicamente mais eficientes.

Does increased scrotal circumference measurement in bulls reduce the age of puberty in their daughters?

#### Bottom line When reviewing the results from a recent bull breeding soundness examination visit to a beef cattle stud, you notice substantial differences in the scrotal circumference (SC) measurements between animals, despite them being the same age and of the same breed. You have often heard it stated that the age at which female offspring reach puberty decreases with an increase in sire SC. However, you would like to confirm this statement with evidence from the literature before discussing breeding recommendations with your client. In the [beef bull], does increased [scrotal circumference] measurement directly reduce [puberty age] in [daughters]? The keywords (bull OR cattle OR male OR beef OR “Bos Taurus”) AND (“scrotal circumference” OR “scrotal size”) AND (“puberty” OR “first service”) AND (progeny OR offspring OR heifer OR daughter) were used to search CAB abstracts and Scopus.

Exame do sistema genital dos animais

O exame completo e exato do sistema genital é de fundamental importância para o diagnóstico e tratamento das afecções reprodutivas. Além disso, o exame ginecológico tem por finalidade detectar a fase do ciclo estral, a gestação e causas da infertilidade da fêmea. O exame andrológico é realizado para atestar o potencial reprodutivo do macho, além de diagnosticar as causas da impotência coeundi e generandi. O exame ginecológico se inicia com a anamnese, seguida pelo exame clínico geral, exame específico externo ( avaliação da vulva e vestíbulo) e exame interno (palpação retal de cérvix, útero e ovários em grandes animais e vaginoscopia) . Os exames complementares são de grande auxílio para o diagnóstico, e consistem em ultrasonografia de útero e ovários, citologia vaginal em pequenos animais, exame histológico, microbiológico, testes sorológicos e dosagens hormonais. A anamnese e o exame clínico geral também são as primeiras etapas do exame andrológico, seguido de exame específico do sistema reprodutor externo (inspeção e palpação de escroto, testículos, epidídimo, funículo espermático e medição da circunferência escrotal) e interno ( palpação retal das glândulas anexas), teste de libido, espermograma e por fim exames complementares como ultrassonografia de glândulas anexas e testículos, sorologia, PCR, testes hormonais, exame microbiológico do sêmen além de testes funcionais dos espermatozóides.

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 + Ɛ. 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.

Predicting the body weight of Balochi sheep using a machine learning approach

Various machine learning algorithms have been used to model and predict the body weight of rams of the Balochi sheep breed of Pakistan. The traditional generalized linear model along with regression trees, support vector machine, and random forests methods have been used to develop models for the prediction of the body weight of animals. The independent variables (inputs) include the body (body length, heart girth, withers height) and testicular (scrotal diameter, scrotal circumference, scrotal length, and testicular length) measurements of 131 male sheep 2-36 months of age. The performance of the models is assessed based on evaluation criteria of mean absolute error, mean absolute percentage error, correlation between observed and fitted values, coefficient of determination, and root mean squared error. A 10-fold cross-validation is done on a training dataset to check the stability of the models. A separate training dataset is used to assess the predictive performance of the developed models. The random forests model was found to provide the best results for both training and testing datasets. It was concluded that machine learning methods may provide better results than the traditional models and may help practitioners and researchers choose the best predictors for body weight of farm animals.

Scrotal circumference, bodyweight and semen characteristics in growing dairy-breed natural-service bulls in Tasmania, Australia

ABSTRACTAims: To provide herd managers with a set of decision rules allowing them to predict the likelihood that a juvenile bull is ready for Bull Breeding Soundness Evaluation (BBSE), or breeding, if bodyweight and scrotal circumference are known.Methods: This was a longitudinal study following two groups of young pasture-fed Holstein and Jersey bulls from northwest Tasmania, Australia. Individual scrotal circumference, bodyweight and semen characteristics were recorded at 6–8 weekly intervals, from 6–18 months of age. Classification and regression tree analyses were used to predict the probability that a bull had ≥70% normal sperm morphology based on scrotal circumference and bodyweight measurements.Results: Overall 1,661 scrotal circumference and bodyweight measurements were obtained, and 518 semen samples from 356 bulls were assessed for sperm morphology, from 16 examination sessions that took place between 29 May 2015 and 17 August 2016. Classification and regression tree analyses generated a decision tree for Holstein bulls with four node endpoints, and for Jersey bulls with three node endpoints. Diagnostic test performance showed that for Holstein bulls, using the node endpoints of scrotal circumference ≥27 cm and bodyweight ≥349 kg, 98% had ≥70% normal sperm (positive likelihood ratio 10.4; 95% CI = 2.7–41), and using the node endpoints of scrotal circumference ≥27 cm and bodyweight between 282–349 kg, 89% had ≥70% normal sperm (positive likelihood ratio 1.6; 95% CI = 0.9–2.6). For Jersey bulls, using the node endpoints of bodyweight ≥259 kg and scrotal circumference ≥29 cm, 88% had ≥70% normal sperm (positive likelihood ratio 3.4; 95% CI = 1.6–7.0).Conclusions: This study provides a set of relatively simple decision rules based on bodyweight and scrotal circumference measurements that allows herd managers to assess the likelihood that juvenile bulls are ready for BBSE or breeding.Abbreviations: BBSE: Bull breeding soundness evaluation; BRT: Boosted regression tree

Relação entre medidas biométricas e peso corporal em ovinos da raça texel

Objetivou-se avaliar a predição do peso corporal de ovinos da raça Texel, por meio de regressões lineares e não-lineares com base nas medidas corporais de perímetro torácico, comprimento corporal, altura de cernelha e circunferência escrotal, bem como descrever o comportamento do crescimento das medidas em relação ao peso. Foram utilizados dados de 200 animais da raça Texel. Os dados foram coletados por técnicos treinados durante exposições agropecuárias que ocorreram no estado do Paraná entre os anos de 2009 e 2014. Os dados de machos e fêmeas foram analisados separadamente. Determinou-se as correlações entre as características estudadas. Todas as características foram significativamente correlacionadas, com o perímetro torácico apresentando maior correlação com o peso corporal (r=0,93 para machos e r=0,90 para fêmeas). Dentre os modelos estatísticos gerados para a predição do peso, os que consideraram o perímetro torácico e altura foram os mais precisos. O comprimento corporal não foi satisfatório na predição. Ao se testar as regressões não-lineares, foi observado que as medidas biométricas apresentaram crescimento alométrico negativo em relação ao peso corporal, indicando que essas medidas aumentam mais rapidamente do que o peso.As medidas corporais, principalmente o perímetro torácico, podem ser usadas como método alternativo para obtenção de peso dos animais.

Early rather than late scrotal circumference measurements better reflect female precocity in beef cattle

In cow-calf operations the moment the heifer achieves her first pregnancy set up her future productivity. Although puberty itself is a yes-or-no condition, time to the event has a quantitative genetic basis and thus is suitable for genetic selection. However, the trait is difficult to measure directly and proxies such as age at first calving (AFC), or scrotal circumference (SC), are typically used. In genetic evaluations, the age at which SC is measured usually corresponds to last part of pubertal development phase. But given that initiation of puberty in both sexes is controlled by the same neuroendocrine mechanisms, we argue that an earlier measurement, taken instead at the start of the pubertal development phase, is probably a better indicator of female precocity. To support the hypothesis, we fitted a multiple-trait animal model on AFC records and SC measurements taken at 300, 400, and 630 days of age and estimated heritabilities and genetic correlations by REML. Importantly, usually AFC data is afflicted by the problem that when breeding season starts most heifers are already cycling (which is, of course, the desired condition) and thus the record poorly reflects precocity. To avoid the problem, in this study we used records collected from an Angus herd in which heifers receive an early natural first service at 375 days of age. Genetic correlation between AFC and SC300 was twice as large as the one corresponding to SC400 (–0.478 ± 0.13 vs –0.244 ± 0.11) and three times larger than to SC630 (–0.478 ± 0.13 vs –0.152 ± 0.12), a result that supports our hypothesis. Heritabilities for SC300, SC400 and SC630 were 0.429 ± 0.07, 0.704 ± 0.07 and 0.576 ± 0.08, respectively, and 0.371 ± 0.05 for AFC. Our results have an important implication in the age at which SC, as an indirect trait for improving precocity, is typically measured in beef cattle breeding programs. Indeed, they indicate that measurements should be taken earlier.

Genetic parameters for fertility and production traits in Red Angus cattle.

Heifer pregnancy (HPG) and Stayability (STAY) are female reproductive traits that have EPD reported by the Red Angus Association of America. Challenges arise when making genetic predictions for these traits. Specifically, HPG and STAY phenotypes can only be collected on females retained in the breeding herd and have low heritability estimates. Additionally, STAY is measured late in an animal's life. The objective of this research was to investigate the genetic relationships between HPG or STAY and 13 other traits, which included measurements of growth, carcass, ultrasound, and scrotal circumference. For STAY relationships between mature weight (MW), body condition score (BCS), teat score (TS), and udder suspension score (US) were also evaluated. Data from 142,146 and 164,235 animals were used in the analyses for HPG and STAY, respectively. Genetic relationships were investigated using a series of 2 trait animal models and a REML procedure. In all analyses, the appropriate contemporary groups were included as a fixed effect, and direct genetic as a random effect. Additional fixed effects included as follows: sex for weight, carcass and ultrasound traits, age of dam for weight traits, and age of measurement for ultrasound, carcass, BCS, udder traits, and MW. Maternal genetic effects for preweaning gain (Pre-WG), weaning weight (WW), and yearling weight (YW) were also modeled. Permanent environmental effects of the dam were modeled for the traits Pre-WG and WW. Permanent environment of the individual for the traits MW, BCS, TS, and US was also included. Heritability estimates were 0.12 ± 0.01 and 0.10 ± 0.01 for HPG and STAY, respectively. Heritability estimates for direct genetic effects of production traits were moderate to high in magnitude, maternal heritability estimates were low, and permanent environmental effects accounted for 0.00 to 0.18 of the total variation. The strongest genetic correlations were those among Pre-WGD (0.24 ± 0.08), WWD (0.18 ± 0.08), YWD (0.20 ± 0.07), ultrasound rib eye area direct (0.16 ± 0.08), and ultrasound backfat direct (0.14 ± 0.08) and HPG. The highest genetic correlations were between STAY and WWM (0.54 ± 0.05), YWM (0.36 ± 0.07), backfat (0.53 ± 0.20), marbling score (0.40 ± 0.20), UREA (0.19 ± 0.07), ultrasound backfat (0.37 ± 0.07), TS (0.30 ± 0.11), and US (0.23 ± 0.11). Relationships between HPG or STAY and other traits were minimal. These results suggest that genetic relationships exist between HPG or STAY and other more densely recorded traits.