Search

This study was conducted to investigate the effects of dietary supplementation of active dry yeast (Saccharomyces cerevisiae) on growth performance, circulating ghrelin, fatty acid concentrations in the gastrointestinal tract, and trace mineral elements utilisation of finishing bulls. Twenty Yanbian cattle (bulls) [body weight (BW) 485 ± 38 kg] were randomly divided into two groups (control and treatment groups) and participated in a 100-day finishing trial. The control group (CON) was fed a basal diet (total mixed ration, TMR). The treatment group (active dry yeast, ADY) was fed a basal diet supplemented with ADY (Levucell SC, Saccharomyces cerevisiae CNCM I-1077, viable count ≥8.0 × 109 CFU/g, 1.0 g/bull/day). ADY supplementation significantly increased the dry matter intake (DMI) of bulls (p <.05); significantly increased the concentration of ghrelin O-acyl transferase (GOAT) (p <.05), significantly decreased the concentration of corticotropin-releasing hormone (CRH) (p <.05), tended to increase the concentration of acyl ghrelin (AG) (p =.053) in serum; significantly increased the content of C12:0 in duodenal digesta, the apparent digestibility of Zn, the concentrations Zn and Cu in serum and the deposition of Cu in the liver (p <.05), significantly decreased the deposition of Fe in muscle in finishing bulls (p <.05). In conclusion, ADY supplementation improved DMI of finishing bulls may be related to the change of AG, and a potential mechanism for the change of AG by ADY supplementation is via its effects on the metabolism of C12:0, Zn, and Cu in finishing bulls. Active dry yeast (ADY) supplementation increased the dry matter intake (DMI) and tended to increase the concentration of acyl ghrelin (AG) in the serum of finishing bulls. ADY supplementation increased the content of C12:0 in duodenal digesta and improved the bioavailability of Zn and Cu of finishing bulls. A potential mechanism for the change of AG by ADY supplementation is via its effects on the metabolism of C12:0, Zn, and Cu in finishing bulls. [ABSTRACT FROM AUTHOR]

The aim of this study was to estimate genetic parameters and investigate the genomic background of scrotal circumference and semen parameters in the Italian Simmental bulls. Scrotal circumference, number of normal spermatozoa, ejaculate volume, spermatozoa motility, and total spermatozoa were measured on 622 bulls, of which 603 had genotypes for 42,141 SNP. Variance components of scrotal circumference were estimated with an animal model that included the fixed effects of birth year, animal age, and measurement method, and the random effects of day of measurement and animal. In the model for the other traits, the scrotal circumference was added as a covariate to account for its influence on the semen parameters. A genome-wide association study was carried out using the ssGBLUP-approach. Heritabilities ranged from 0.07 ± 0.05 (spermatozoa motility) to 0.50 ± 0.14 (scrotal circumference). A total of 13 SNP passed the Bonferroni correction threshold and the number of significantly associated markers ranged from 1 (ejaculate volume and spermatozoa motility) to 5 (total spermatozoa). Genes already associated with reproduction parameters were retrieved close to the significant SNP. Results of the present study gave preliminary insights about the genetic determinism of semen quality in Italian Simmental bulls. Low to moderate heritabilities were estimated for semen traits. Few markers were associated with the phenotypes, suggesting their polygenic determinism. Candidate genes already associated in literature with sperm traits were found. [ABSTRACT FROM AUTHOR]

To characterise the main Italian dual-purpose breeds in terms of feed efficiency and behaviour, the dry matter intakes (DMI) of 890 young bulls were collected using automatic feeding systems in two Italian genetic centres. In Experiment 1, Italian Simmental (IS), Rendena (RE) and Alpine Grey (AG) young bulls were fed total mixed ration for 46 days. In Experiment 2, Valdostana Red Pied (VR) and Black Pied and Chestnut (VB) young bulls were fed hay and concentrate for 60 days. The IS and RE bulls grew faster than AG (1.6 vs. 1.3 kg/d, p <.01). The DMI was highest for IS and lowest for AG while all breeds had similar values for DMI expressed as relative to body weight. Overall, RE and AG bulls were more efficient than IS. Regarding feeding behaviour, the number of feeding events for IS and AG was higher than for RE, while the feeding time was not different between breeds. The IS bulls showed a higher value of feeding rate (FR) than RE and AG (98.2 vs. 83.1–86.5 g DM/min, p <.01). Overall AG breed, despite its high feeding activity, was particularly efficient. In addition, efficient animals showed a low FR compared to inefficient ones. In Experiment 2, VR and VB strains were quite similar in terms of growth capacity but VR was more efficient despite its higher daily activity. In conclusion, dual-purpose breeds can reach notable growths and feed efficiencies and FR is well related to feed efficiency. Rendena and Alpine Grey bulls are slightly more efficient than Italian Simmental bulls Valdostana strains differ for feed efficiency but not for growth capacity Feeding rate is a useful behaviour trait to consider in the study of feed efficiency [ABSTRACT FROM AUTHOR]

Livestock farming is directly responsible for greenhouse gas (GHG) emissions, mainly due to enteric fermentation. Feed efficiency in livestock species is generally evaluated through feed conversion ratio (FCR) and residual feed intake (RFI), which are associated to GHG emissions. The aim of this study was to characterise FCR and RFI in relation to body traits, feed intake, feeding behaviour and GHG emissions of Holstein bulls. Data were collected between May 2018 and July 2020 on 111 animals. Pearson correlations between studied traits were estimated on the residuals obtained from a linear mixed model which included the fixed effect of the linear covariate of age of bull on the dependent variable and the random effect of the bull. To assess the effect of RFI and FCR the same linear mixed model was implemented firstly by including the fixed effect of RFI (2 classes) and secondly the fixed effect of FCR (2 classes). Correlations between dry matter intake (DMI) and GHG ranged from 0.25 (CH4) to 0.36 (CO2). The strongest relationship was estimated between feed efficiency traits and DMI (0.86). RFI and FCR showed weak to moderate correlations with GHG (0.12–0.31). Animals belonging to the low classes of RFI and FCR had lower DMI and showed significant reduction of GHG emissions. Results of the present study highlighted significant differences in terms of feed efficiency and GHG emissions among tested animals; further research is needed on their progeny to investigate the genetic background of the same efficiency and emission-related traits. Feed efficiency and emission of greenhouse gases vary among Holstein bulls. Dry matter intake and feed efficiency traits were strongly positively associated. Animals endowed with greater feed efficiency had lower emissions and feed intake. Results of the present study will be useful to select animals for feed efficiency. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate how different rearing systems (intensive or semi-extensive) and sexual hormones could affect stress parameters and the development of stress-related intramural coronary arteriosclerosis in Lidia bulls (n = 18) and Piemontese oxen (n = 17). At slaughter, hearts were sampled and submitted to histological investigations in order to evaluate coronary arteriosclerosis. Blood and hair samples were also collected to measure d-ROMS and 20β-dihydrocortisol levels, respectively. No significant differences were recorded for serum levels of d-ROMS between Piemontese oxen and Lidia bulls. On the contrary, Lidia bulls presented higher levels of hair 20β-dihydrocortisol compared to Piemontese oxen (p =.007). Arteriosclerosis was recorded in both the groups. In Lidia bulls, mild to moderate coronary arteriosclerosis was recorded in all the evaluated regions of the heart (right and left papillary muscle; interventricular septum; right and left ventricle free wall; right and left atrium). In Piemontese oxen, mild to severe coronary arteriosclerosis was observed, especially in the left papillary muscle. These results suggest that both cattle breed experienced stress during their rearing cycle. Further studies are needed to clarify the role of housing system and sexual hormones in the development of these subclinical vascular pathology. Rearing systems can affect animal welfare. Coronary arteriosclerosis, d-ROMS and hair 20β-dihydrocortisol levels can be affected by stress. Lidia bulls and Piemontese oxen experienced different levels of stress during their rearing cycle. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of different shading strategies on the intake and digestibility of nutrients, nutrient use efficiency, feeding behaviour, respiratory rate, and performance of feedlot-finished Nellore bulls in the semi-arid region of Brazil. Two hundred and twenty-five intact Nellore cattle with average body weight (BW) of 294 ± 19 kg and 24 months of age were allotted to a completely randomised design with three shading strategies (full sun, artificial shade, and natural shade). There was a significant effect of shading strategies on air temperature (p =.02), black globe temperature (p <.01), and radiant heat load (p <.01), which were 3.63%, 44.07%, and 4.10% higher in the full sun pen than in natural shade pen, respectively. The dry matter intake of animals kept in the natural shade pen was 14.76% higher than that of animals in the full sun pen (mean of 7.39 kg DM/day). The longest feeding time (p =.02) was observed in animals kept in the artificial shade pen. Bulls kept in the natural shade pen had the highest (p =.05) final body weight and average daily gain (p =.02). There was no effect of treatments on feed efficiency, averaging 0.184 kg/kg of DM. There was a trend (p =.09) towards higher hot carcase weight for animals kept in the natural shade pen. Natural shade is recommended for feedlot-finished Nellore cattle in the semi-arid region of Brazil. Natural shade in feedlot pens improves the thermal comfort of animals in the semi-arid region The dry matter intake was higher in bulls kept in the pen with natural shade than in animals kept in the full sun pen Animal performance was improved in shaded pens [ABSTRACT FROM AUTHOR]

With the aim of assessing bull fertility before or during its use for reproduction under tropical weather conditions where heat stress is present, and correlating it to herd parameters, BSE was carried out to determine which genetic groups of bulls have better reproductive performance. 223 bulls from different genetic groups, Zebu bulls (N = 72), European bulls (N = 58), and Crossbred Bulls (N = 93), were evaluated in situ over a two-year period, 2018–2019. Bull (age, corporal conditions, libido, and scrotal circumference), semen (concentration, motility and volume), herd (pregnancy rate and calving intervals) and environmental variables (THI, season, sampling month and spermatogenesis month) were analysed with One-Way ANOVA, as well as with factorial, multiple regression, and multivariate analysis. Zebu and European bulls have a higher libido than crossbreed bulls (p <.05), and it decreases with age (p <.05). High-libido bulls (>7) show high correlation (R = 0.70 p <.05) with herd parameters; BCS affects libido (p <.05). Sperm concentration is correlated to herd parameters (R = 0.82 p <.05). European bull sperm concentration and motility showed a decrease in autumn and winter (p <.05) in comparison to other genetic groups. Libido and semen variables are more associated with herd parameters than with other bull characteristics. Environmental variables are not associated with herd parameters (p >.05). Heat stress did not directly affect bull reproductive performance; Zebu bulls and crossbreeds showed better herd parameters (p <.05). Bull breeding soundness examination and herd proficiency. Herd proficiency of local genetic groups of bulls in tropical conditions. Breeding soundness examination in tropical environment conditions. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate animal performance, carcase characteristics and meat quality of young bulls and steers (Charolais × Holstein-Friesian), fattened until 15 and 18 months of age. One half of 40 young bulls were castrated at 2 or 3 weeks of age. Starting at 7 months of age, they received grass silage supplemented with concentrates. At the end of the fattening period, the animals were slaughtered, and carcase quality and the quality of meat from Musculus longissimus thoracis (MLT) were evaluated. Bulls had a higher carcase dressing percentage, and their carcases had higher lean meat content than steers. MLT from steers had higher intramuscular fat (IMF) content (by 0.89%); it was less tough, more tender and palatable. IMF from bulls had higher concentrations of polyunsaturated fatty acids (PUFAs) and a higher n-6/n-3 PUFA ratio than IMF extracted from steer meat. Older animals had higher carcase quality than those slaughtered at 15 months of age, and slaughtering at a later age had no negative influence on meat quality.

The experiment was aimed to evaluate the usefulness of hair cortisol concentrations (HCC) in revealing the activation of the hypothalamic-pituitary-adrenal (HPA) axis due to the passage of young bulls from genetic rearing stations to artificial insemination (AI) centre and the influence of this passage on hair testosterone concentrations (HTC). Hair samples on 33 yearling bulls were collected at the time of arrival (ST1) to the AI centre and 3 more hair samples (ST2, ST3, ST4) were collected at monthly intervals. After the end of quarantine each animal was submitted to the standard procedures for collection and production of semen. Overall HCC were significantly affected by period of collection (p .05). The effect of breed was observed only for HTC that was higher in PRI than BS (p .05). On the contrary, the effect of breed was evident. The results of this study replicated the effects of a major environmental stressor on mean cortisol concentrations assessed in hair, and add to the growing body of evidence that HCC is an effective and simply collected marker for long-term activity of the HPA system in response to persistent environmental challenge.

The EUROP classification system includes only a small number of indicators to characterise beef carcases, none of which directly describes meat quality. Therefore, beef producers show limited interest in improving meat quality parameters. The aim of this study was to evaluate whether conformation and fat cover, as assessed in the EUROP classification system, can be reliable descriptors of the qualitative characteristics of beef carcases and meat quality. A total of 198 carcases of young bulls were analysed. Meat samples were collected from the longissimus thoracis (LT) muscle. It was found that the muscle content of three-rib cuts was higher in better-conformed carcases. Conformation class was inversely related to intramuscular fat (IMF) content, the fat content of three-rib cuts and meat juiciness. Meat quality was better characterised by fat class than conformation class. The fat cover had a positive influence on shear force values, the water-holding capacity and tenderness of meat. The water-holding capacity of meat and shear force values can be used in addition to EUROP scores to more accurately characterise beef carcases. Better conformed carcases have lower intramuscular fat content, lower fat content of three-rib cuts, higher shear force values and lower juiciness scores; Fat cover is a more reliable indicator of meat quality than carcase conformation; Water-holding capacity and shear force can be used in addition to EUROP scores. [ABSTRACT FROM AUTHOR]

Thirty-six Holstein bulls (initial body weight, 345 ± 61 kg) were randomly assigned to six dietary treatments with a 2 × 3 factorial arrangement, with two levels of AH (alfalfa hay) (10 and 20% of AH) combining with three levels of FO (fish oil) (0, 1 and 2.1% of DM) to investigate the effects of AH proportion and FO supplementation on performance, carcase characteristics, and meat fatty acids profile. DMI (dry matter intake) (kg/day) was lower (p <.01) for high (8.0) than for low (8.7) AH. Highest level of FO reduced DMI (p <.01) regardless of AH level. Dietary inclusion of FO increased the concentration of VA (p <.01), CLA (p <.01) and n-3 (p <.01) fatty acids which subsequently reduced n-6: n-3 (p <.01). The results indicate that AH can be replaced by corn (zea mays) silage to mitigate the detrimental effect of supplemented fat on dry matter intake. Moreover, FO can be supplemented to feedlot diet to enrich ruminant products without deleterious effects on carcase characteristics. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate animal performance, carcase characteristics and meat quality of young bulls and steers (CharolaisHolstein-Friesian), fattened until 15 and 18 months of age. One half of 40 young bulls were castrated at 2 or 3 weeks of age. Starting at 7 months of age, they received grass silage supplemented with concentrates. At the end of the fattening period, the animals were slaughtered, and carcase quality and the quality of meat from Musculus longissimus thoracis (MLT) were evaluated. Bulls had a higher carcase dressing percentage, and their carcases had higher lean meat content than steers. MLT from steers had higher intramuscular fat (IMF) content (by 0.89%); it was less tough, more tender and palatable. IMF from bulls had higher concentrations of polyunsaturated fatty acids (PUFAs) and a higher n-6/n-3 PUFA ratio than IMF extracted from steer meat. Older animals had higher carcase quality than those slaughtered at 15 months of age, and slaughtering at a later age had no negative influence on meat quality. [ABSTRACT FROM AUTHOR]

The aim of this trial was to compare the growth performance and meat yield and composition of SimGoud (Italian Simmental × Goudali, SG) crossbreed young bulls with those of pure Goudali (G) breed. Twenty-five G and 25 SG, from 20 to 41 months, reared together in Cameroon on native pasture were considered. Body size, growth and meat composition were compared. The SG crosses were more sized than the coetaneous pure G, having almost all body dimensions and mass index higher than G. Moreover, SG showed higher body weight at farm andante-mortemthan G, with about four times higher growth rate, but showed a marked loss of weight during transfer to slaughterhouse and lairage time. SG showed higher carcass weight and killing out percentage, in addition to a higher weight of rib steak and ribeye muscle at eighth–ninth rib section level than G. Despite the greater growth, differences between G and SG in beef proximate composition were not found. Genotype had a limited effect on fatty acids profile. However, G beef had greater CLA level, but lower MUFA content than SG. The study showed that G pure breed has much lowerin vivoand slaughter performance than their crosses with the Italian Simmental breed, even if the meat composition was not different between the two genotypes. Conversely, despite similar pH of meat, G was more adaptable than SG to the severe transport condition and to the prolonged lairage time. [ABSTRACT FROM PUBLISHER]

The experiment was aimed to evaluate the usefulness of hair cortisol concentrations (HCC) in revealing the activation of the hypothalamic-pituitary-adrenal (HPA) axis due to the passage of young bulls from genetic rearing stations to artificial insemination (AI) centre and the influence of this passage on hair testosterone concentrations (HTC). Hair samples on 33 yearling bulls were collected at the time of arrival (ST1) to the AI centre and 3 more hair samples (ST2, ST3, ST4) were collected at monthly intervals. After the end of quarantine each animal was submitted to the standard procedures for collection and production of semen. Overall HCC were significantly affected by period of collection (p<.01). In particular, HCC was higher in samples obtained after finishing the quarantine period (ST2) compared with those obtained on ST1. After ST2, the HCC decreased reaching at ST4 a value similar to that recorded at ST1. An effect of sampling time on HTC was not found (p>.05). The effect of breed was observed only for HTC that was higher in PRI than BS (p<.01). The HCC group have not influenced the semen variables (p>.05). On the contrary, the effect of breed was evident. The results of this study replicated the effects of a major environmental stressor on mean cortisol concentrations assessed in hair, and add to the growing body of evidence that HCC is an effective and simply collected marker for long-term activity of the HPA system in response to persistent environmental challenge. [ABSTRACT FROM AUTHOR]

Bos indicus (n=67) and crossbred Bos taurus x Bos indicus (n=67) bulls were finished in extensive or intensive conditions to evaluate the effect of genetic differences and finishing system on the fatty acid (FA) composition of intramuscular fat. Finishing system had a more pronounced effect on FA profiles than the genetic group, but the two factors often interacted for both individual and groups of FA. When compared with animals finished intensively, those finished on pasture produced meat with higher concentration of CLA and polyunsaturated n-3 FA, in particular of 18:3, 20:5 and 22:5. Meat from animals finished intensively had higher amounts of 14:0, 16:0, 18:1 trans-10, 18:1 trans-11, monounsaturated trans FA and 18:2. When the two genetic groups were compared under intensive finishing, B. indicus animals showed lower amounts of 20:4 (synthesised from 18:2) and 20:5 (synthesised from 18:3), suggesting that they may have a lower ability in biochemical pathways involved in the metabolism of n-6 and n-3 long chain fatty acids. Overall, meat from animals finished on pasture had a higher amount of the FA considered desirable for human health. [ABSTRACT FROM AUTHOR]

The present study aimed to predict conformation and fatness grades in bulls based on data available at slaughter (carcass weight, age and breed proportions) by means of counter- propagation artificial neural networks (ANN). For chemometric analysis, 5893 bull carcasses (n=2948 and n=2945 for calibration and testing of models, respectively) were randomly selected from the initial data set (n≈27000; one abattoir, one classifier, three years period). Different ANN models were developed for conformation and fatness by varying the net size and the number of epochs. Tested net parameters did not have a notable effect on models' quality. Respecting the tolerance of ±1 subclass between the actual and predicted value (as allowed by European Union legislation for on-spot checks), the matching between the classifier and ANN grading was 73.6 and 64.9% for conformation and fatness, respectively. Success rate of prediction was positively related to the frequency of carcasses in the class. [ABSTRACT FROM AUTHOR]

Sixteen Podolian young bulls were used to study the effects of two different feeding systems on fatty acids composition and oxidative stability of meat: C group, eight young bulls were kept indoors and fed with commercial concentrate for all experimental period (260 days); PC group, eight young bulls were allowed to graze a pasture for 200 days and shifted indoor, fed with concentrate, 60 days before being slaughtered. Meat from young bulls that were allowed, before stall finishing with concentrate, to graze a natural pasture showed lower levels of some n-6 PUFA and higher levels of some n-3 PUFA than meat from animals that were offered only concentrate for the whole experimental period. Lipid oxidation was not affected by the dietary treatment. After a period of 60-day-indoor finishing with concentrate, meat retained part of the health benefits, with regard to fatty acid composition, occurring from grazing. [ABSTRACT FROM AUTHOR]

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is a selenoprotein, which protects biomembranes from oxidative damages, and it also accounts for almost the entire selenium content of mammalian testis. The present investigation was performed to localise PHGPx in the testis and in epididymal and ejaculated spermatozoa of the bull by using light and electron immunomicroscopy. The study also aimed to further clarify the possible functions of the protein in bull fertility. In the testis, spermatogenic cells of the adluminal tubular compartment showed cytoplasmatic immunostaining; whereas, in the epididymal and ejaculated spermatozoa immunostaining was specifically localised at the level of the head and mid-piece. Ultrastructural data revealed the presence of signals for PHGPx in different subcellular compartments of maturing and mature sperm (mitochondria, chromatin, nuclear envelope, acrosomes, cytoskeletal structures) suggesting that this enzyme plays versatile and important biological roles during spermatogenesis. The final localisation of the immunostaining at acrosomal level puts forward a new role of the protein which further emphasises its relevance in male reproduction: it is reported to anchor substrate of the sperm acrosome to the oocyte zona pellucida during the fertilisation process. [ABSTRACT FROM AUTHOR]

ad libitum basis to increase the flexibility of their work. Including salt, which is a self-limiting supplement, could control or reduce concentrate intake without increasing the workforce. The aim of the study was to evaluate the effect of including 10%NaCl in the concentrate on intake, growth, blood ions (sodium, potassium and chlorine), renal function (through creatinine and urea concentrations in blood), and daytime behaviour of bulls over 6 weeks. Bulls consuming the control concentrate (Control bulls) had greater weight gain (P<0.05) and concentrate intake (P<0.001) than those consuming the concentrate with 10%NaCl (10%NaCl bulls). Lower plasma sodium concentration was found in Control bulls after 6 weeks (P<0.05), while potassium concentration was lower after 4 (P<0.05) and 6 weeks (P<0.01). Blood urea did not differ between the groups, and creatinine only differed at week 4 (P<0.01). Control bulls spent less time eating hay (P<0.001) and more time idling (P<0.01) during daylight hours. In conclusion, the inclusion of 10%NaCl in the concentrate for short periods could be used to reduce concentrate intake without major effects on renal function; however, a concomitant decrease in weight gain should be expected. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of body weight (BW) at slaughter and fattening intensity on carcass fatness and meat fatty acid profile in young Holstein- Friesian bulls. One-hundred bulls fattened on two levels of intensity a semi-intensive (SI) and an intensive (I) were used. Fattening was carried out to BW of 500, 550, 600, 650 and 700 kg. Live ultrasound measurements were performed to determine back fat thickness. Carcass dressing percentage, carcass conformation and fatness, intramuscular fat content of m. longissimus dorsi and fatty acid profile (by gas chromatography) were determined after slaughter. Intensively fattened bulls were characterised by a greater carcass dressing percentage - by 1.17% on average, greater carcass conformation scores, greater external fat thickness and a greater intramuscular fat content than bulls SI fattened. Fat from intensively fattened bulls contained higher levels of polyunsaturated fatty acids (PUFAs) - by 0.96/100 g on average. Semi-intensive fattening contributed to a decrease in the n-6/n-3 PUFA ratio and to a significant increase in the concentrations of C18:2 and C20:4 fatty acids. Regardless of the fattening intensity, the n-6/n-3 ratio was greater in heavier animals. The best results were achieved when young Holstein-Friesian bulls were fattened intensively to BW of 650 kg. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate factors influencing the number of daughters of Holstein bulls during the progeny testing using data provided by the Italian Holstein Friesian Cattle Breeders Association. The hypothesis is that there are no differences among artificial insemination studs (AIS) on the daughters distribution among progeny testing bulls. For each bull and beginning from 21 months of age, the distribution of daughters over the progeny testing period was calculated. Data were available on 1973 bulls born between 1986 and 2004, progeny tested in Italy and with at least 4 paternal half-sibs. On average, bulls exited the genetic centre at 11.3±1.1 months and reached their first official genetic proof at 58.0±3.1 months of age. An analysis of variance was performed on the cumulative frequency of daughters at 24, 36, 48, and 60 months. The generalized linear model included the fixed effects of year of birth of the bull (18 levels), artificial insemination stud (4 levels) and sire of bull (137 levels). All effects significantly affected the variability of studied traits. Artificial insemination stud was the most important source of variation, followed by year of birth and sire of bull. Significant differences among AI studs exist, probably reflecting different strategies adopted during progeny testing. [ABSTRACT FROM AUTHOR]

This study aimed at evaluating the relationship between physical and morphological semen features with the hypoosmotic swelling (HOS) test in raw semen of adult Nelore bulls classified as sound and unsound for breeding. Two hundred and six Nelore bulls aging from 3 to 10 years of age were subjected to breeding soundness examination. After physical and morphological semen examination, HOS test was done. After the breeding soundness examination, 94.2% of the bulls were classified as sound for breeding. There was no difference between the average scrotal circumference of bulls classified as sound and unsound for breeding (P>0.05), but there was difference between all semen physical and morphological aspects of bulls classified as sound and unsound for breeding (P>0.05), and no difference resulted in the mean percentage of reactive spermatozoa to HOS test results both for sound (38.4±17.9) and unsound animals (39.5±16.4; P>0.05), with no Pearson correlation between the HOS test and variables. According to these results HOS test can not be used alone to predict the reproductive potential of adult Nelore bulls. [ABSTRACT FROM AUTHOR]