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The aim of the experiment was to assess the correlation between sperm quality parameters and field fertility after AI with sex-sorted (X-bearing) bull semen. A total of 32 ejaculates from 26 Holstein-Friesian bulls were analyzed to assess sperm motility parameters (CASA), viability (SYBR-14/PI), apoptotic-like changes (YO-PRO-1/PI), chromatin structure (SCSA), and ATP content. In order to determine sperm fertilizing ability, 816 heifers and 727 cows were inseminated. Ultrasound diagnosis of pregnancy was performed on day 35 after insemination. For each ejaculate, the percentage of pregnant females was calculated separately. The results revealed that the pregnancy rate ranged from 20.0 to 85.7% for heifers and from 7.7 to 66.7% for cows. On the basis of the pregnancy rate (PR) obtained, the ejaculates were divided into 3 groups: high PR (about 25% of ejaculates), medium PR (about 50% of ejaculates) and low PR (about 25% of ejaculates). Significant differences were detected for amplitude of lateral head displacement (ALH) and beat cross frequency (BCF) between high- and low-fertility ejaculates in heifers. Pearson's correlation analysis showed a significant relationship between the BCF and the pregnancy rate for heifers (r = 0.53, P<0.01) and there was a trend towards significance for ALH (r = −0.37, P = 0.07). There was no relationship between the sperm quality parameters and pregnancy rate of cows. In conclusion, the present study identified markers of sexed bull sperm function that were related to the fertility of inseminated heifers. [ABSTRACT FROM AUTHOR]

Objective The objective of this study was to compare growth performance, carcass traits and meat quality in young bulls, steers and heifers produced by crossing Limousin bulls with Holstein-Friesian cows, fattened semi-intensively and slaughtered at 18 months of age. Methods Thirty-one young calves were reared in a conventional production system, and were fed milk replacer, hay and concentrate. At 6 months of age, the animals were divided into groups based on gender, and were fed a total mixed ration composed of grass silage, concentrates I and II in a semi-intensive production system. At the end of the fattening period (18 months), the animals were slaughtered, carcass quality was evaluated, and samples of musculus longissimus thoracis were collected to determine the proximate composition and quality of meat. Results Bulls were characterized by the highest percentage share of the most valuable cuts in the carcass, and three-rib sections from bull carcasses had the highest lean meat content with low intramuscular fat content (0.93%). No significant differences in carcass conformation, dressing percentage or the percentage share of round in the right half-carcass were found between bulls vs. steers and heifers. Heifers and steers had higher carcass fat content than bulls, which had a positive influence on the sensory properties of beef. In comparison with the meat of bulls, the meat of steers and heifers was characterized by more desirable physical properties and sensory attributes (water-holding capacity, shear force, color lightness, aroma, juiciness, tenderness, flavor). Conclusion Under the semi-intensive production system, heifers and steers had higher carcass fat content than bulls, which had a positive effect on the sensory properties of beef. Bulls are better suited for intensive systems, which contribute to improving the quality of their meat. The results of this study may encourage producers to breed steers and heifers for beef.

Inbreeding is generally associated with a reduction in production and profitability. Therefore, it is essential that it be monitored and kept under control. The purpose of this study was to calculate the inbreeding coefficient for Holstein Friesian cattle registered in the database of the Cattle Breeders' Associations of Turkey (CBAT). In this study, preherdbook and herdbook databases were combined. The database consisted of 6,935,005 individuals born between 1962 and 2012. Inbreeding coefficients were calculated using Wright's method, and ranging from zero to 43.75% with a mean of 0.0012 and standard deviation (SD) of 0.01273 for all animals, and considering the inbred animals, the mean inbreeding coefficient was 0.0106 and standard deviation was 0.03272. The average inbreeding of all animals born in the population in 2012 was found to be 0.0022. In the population, the proportion and the number of inbred individuals increased over the years, while the mean inbreeding coefficient decreased. This could be due to the fact that gene flow in the population from different countries was considerably high, and pedigree information was taken into account while importing sperm and live animals (both heifers and bulls). [ABSTRACT FROM AUTHOR]

Dairy heifers in New Zealand are typically naturally mated by Jersey bulls to produce low-value non-replacement offspring sold for slaughter a few days after birth. Producing a beef-sired calf from a dairy heifer will increase the value of these calves for beef production but may compromise the subsequent career of the animals, in terms of milk production, rebreeding success, health, or survival of the heifer. This study aimed to determine the impact of low birthweight Angus and Hereford bulls versus breed-average Jersey bulls on the reproduction and production traits of first-calving dairy heifers. The experiment included 304 heifer-calf pairs over 2 years. Calves sired by Angus and Hereford bulls were 3.5–4.4 kg and 3.7–6.8 kg heavier than Jersey-sired calves and had a 4.2% and 9.3% incidence of assistance at birth for normally presented calves over the 2 years, respectively. No normally presented Jersey-sired calves were assisted. There was no difference in body condition score, pre-calving live weight, milk production, pregnancy rate, inter-calving interval, re-calving day, and 21-day re-calving rate of heifers mated to the different breeds of bulls. The results indicate that the Angus and Hereford bulls with low birthweight and high direct calving ease estimated breeding values (EBV) can be used to produce calves of greater value than Jersey-sired calves without impacting dairy heifer production. However, a small increase in assistance at calving could be expected. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to compare growth performance, carcass traits and meat quality in young bulls, steers and heifers produced by crossing Limousin bulls with Holstein-Friesian cows, fattened semi-intensively and slaughtered at 18 months of age. Methods: Thirty-one young calves were reared in a conventional production system, and were fed milk replacer, hay and concentrate. At 6 months of age, the animals were divided into groups based on gender, and were fed a total mixed ration composed of grass silage, concentrates I and II in a semi-intensive production system. At the end of the fattening period (18 months), the animals were slaughtered, carcass quality was evaluated, and samples of musculus longissimus thoracis were collected to determine the proximate composition and quality of meat. Results: Bulls were characterized by the highest percentage share of the most valuable cuts in the carcass, and three-rib sections from bull carcasses had the highest lean meat content with low intramuscular fat content (0.93%). No significant differences in carcass conformation, dressing percentage or the percentage share of round in the right half-carcass were found between bulls vs. steers and heifers. Heifers and steers had higher carcass fat content than bulls, which had a positive influence on the sensory properties of beef. In comparison with the meat of bulls, the meat of steers and heifers was characterized by more desirable physical properties and sensory attributes (water-holding capacity, shear force, color lightness, aroma, juiciness, tenderness, flavor). Conclusion: Under the semi-intensive production system, heifers and steers had higher carcass fat content than bulls, which had a positive effect on the sensory properties of beef. Bulls are better suited for intensive systems, which contribute to improving the quality of their meat. The results of this study may encourage producers to breed steers and heifers for beef. [ABSTRACT FROM AUTHOR]

Background: Nellore cattle (Bos indicus) are well-known for their adaptation to warm and humid environments. Hair length and coat color may impact heat tolerance. The Nellore breed has been strongly selected for white coat, but bulls generally exhibit darker hair ranging from light grey to black on the head, neck, hump, and knees. Given the potential contribution of coat color variation to the adaptation of cattle populations to tropical and sub-tropical environments, our aim was to map positional and functional candidate genetic variants associated with darkness of hair coat (DHC) in Nellore bulls. Results: We performed a genome-wide association study (GWAS) for DHC using data from 432 Nellore bulls that were genotyped for more than 777 k single nucleotide polymorphism (SNP) markers. A single major association signal was detected in the vicinity of the agouti signaling protein gene (ASIP). The analysis of whole-genome sequence (WGS) data from 21 bulls revealed functional variants that are associated with DHC, including a structural rearrangement involving ASIP (ASIP-SV1). We further characterized this structural variant using Oxford Nanopore sequencing data from 13 Australian Brahman heifers, which share ancestry with Nellore cattle; we found that this variant originates from a 1155-bp deletion followed by an insertion of a transposable element of more than 150 bp that may impact the recruitment of ASIP non-coding exons. Conclusions: Our results indicate that the variant ASIP sequence causes darker coat pigmentation on specific parts of the body, most likely through a decreased expression of ASIP and consequently an increased production of eumelanin. [ABSTRACT FROM AUTHOR]

Calving difficulty is associated with cow mortality, calf loss, veterinary and labor costs, and causes delayed return to estrus and lower conception rate. Dystocia is common in heifers, and the frequency decreases with the increasing age of the cow. Farmers need to consider both genetics and management factors in an attempt to reduce dystocia. Calf birth weight, the pelvic area of the dam and their interrelationships are major determinants of dystocia. The weight of the calf is governed by genetic, environmental and management factors. Genetic factors include sex, length of gestation, breed, inbreeding, and genotype. Non-genetic factors include age and parity of the dam, nutrition of the dam during various phases of gestation, and environmental temperature and humidity. Dystocia management must begin with a selection of heifer for mating with respect to the body weight of heifers, body condition score (BCS) and dam's pelvic area should be considered before heifer selection. Not only heifer selection but sire selection using an estimated breeding value for calving ease should also be considered to lessen the dystocia rate in a herd. A combination of culling heifers with small pelvic areas and using bulls reported to be calving ease sire may reduce dystocia significantly. Apart from all these factors, genomic selection for reducing calving difficulties is a new tool for dystocia management. [ABSTRACT FROM AUTHOR]

There are presented the results of studies of the exterior and economically useful characteristics of first calf heifers of the local generation of the Holstein breed, bred in a herd of Joint-Stock Company “Aydyn”, Komrat, Administrative and Territorial Unit Gagauzia, Republic of Moldova. The bone index in comparison with the standard turned out to be on average 8.3% lower, which is due to the high height at the withers of Holstein cows. Comparative analysis of milk productivity of daughters of various bulls showed that milk yield for 305 days of lactation of daughters of bull Forms 999 is 155 kg more milk than that of daughters of bull Kiperush 79. Realization of the genetic potential of first-calf heifers of local selection was at the level of 91.4-92.1% of the productivity of full-aged cows, with a fat content of 3.82- 3.89%. The relationship between the milk yield and the percentage of fat in the milk of the daughters of the analyzed bulls was in a positive correlation from the weak (+0.034, daughter of Kiperush 79), to moderate (+0.369, daughter of Forms 999). [ABSTRACT FROM AUTHOR]

This experiment evaluated the effect of pre-weaning plane of nutrition of dams upon reproductive development in Bos indicus x Bos taurus bull offspring reared under extensively managed conditions in the northern Australia rangelands. Following artificial insemination (AI cohort; n = 26), or natural mating (NM cohort; n = 36), grazing primiparous heifers received either nil supplement (Control; CON), thereby experiencing a moderate nutritional restriction, or were provided a protein supplement (SUPP) between parturition and weaning at mean age 199 ± (SD) 26 d. Bull progeny grazed rangeland pastures without supplementation from weaning until the experiment concluded at 675 d. At 120 ± 3 d and 140 d ± 10 d age, within the AI and NM cohort, respectively, bull calves were subjected to a GnRH challenge (1.5 μg/kg of body weight i.m.). Jugular blood samples collected immediately before and at 60 min after administration of GnRH were analysed for LH, FSH, testosterone and inhibin concentrations. Overall mean concentrations of testosterone in SUPP bulls were greater in both the AI cohort (P = 0.05) and the NM cohort (P = 0.06). At 60 d intervals during the post-weaning period, scrotal circumference (SC) was measured and semen collected to assess concentration, progressive motility and morphology of sperm. Bulls reared by SUPP heifers had greater (P = 0.05) SC at 375 d and tended to have greater (P = 0.09) mean percentage of morphologically normal sperm (PNS). Within the NM cohort, NMSUPP bulls had greater (P = 0.04) overall mean SC and tended (P = 0.07) to demonstrate both greater progressive motility and PNS. A greater incidence of sperm morphological abnormalities, associated with sexual immaturity, were observed in CON bulls. Consequently, NMCON bulls demonstrated delayed (P = 0.03) age of sexual maturity as compared to NMSUPP bulls. In summary, improving the plane of nutrition supplied to Bos indicus x Bos taurus bulls between parturition and weaning via moderate supplementation of grazing dams reduces age at sexual maturity with consequent economic advantages to the producer. • Lactational supplementation of primiparous heifers initiates increased calfhood testosterone concentrations of bull progeny. • Enhanced testicular development of bull progeny increases scrotal circumference, sperm motility and morphology. • Effects commensurate with hastened reproductive development and were manifested in early age at sexual maturity. • These findings upon measured bull traits are both practically and economically relevant to the seedstock producer. [ABSTRACT FROM AUTHOR]

The practice of feeding replacement-breeding bulls on high energy diets after weaning to meet liveweight (LW) and carcass expectations between 18 and 24 months of age negatively affects reproductive potential. This experiment reports upon the effects of an alternative management strategy aimed at improving calfhood nutrition in rangeland-reared bulls to enhance LW and live carcass characteristics at 2 years. Following artificial insemination (AI cohort; n = 26), or natural mating, subsequent to the addition of bulls at 39 d post-AI (NM cohort; n = 36), primiparous Santa Gertrudis heifers grazing rangeland pastures with bull calf progeny were allocated at parturition to receive either nil supplement (control; CON) or provided with unrestricted access to a pelleted vegetable protein meal-based supplement containing 35% CP (SUPP) until weaning at 199 ± (SD) 26 d. The mean estimated pellet consumption by SUPP heifers during lactation was 2.6 ± (SEM) 0.5 kg DM daily. Grazing diet quality measurements indicated nutritional restriction of CON heifers until at least 115 d of lactation. This was confirmed by lower blood urea nitrogen concentrations at 88 d (P < 0.001) and greater mean NEFA (P < 0.001) concentrations. Rainfall during mid-lactation subsequently improved grazing diet quality; thus the CON heifers experienced moderate nutritional restriction across lactation, but sufficient to reduce milk yield by 1.6 kg/d (P < 0.001) and maternal LW at weaning by 18.4 kg (P < 0.001). Bulls reared by SUPP heifers were 17.5 kg heavier at weaning (P = 0.001) and had elevated IGF-I and leptin concentrations between 4 and 4.5 months of age (P < 0.05). Effects on metabolic hormones during calfhood were cohort specific, with greater concentrations of IGF-I confined to AISUPP bulls and NMSUPP bulls demonstrating greater concentrations of leptin. Bulls were amalgamated at weaning and grazed common pastures without supplementation until the experiment concluded at 675 d. Pre-weaning plane of nutrition did not affect the LW, carcass fat depth, IGF-I or leptin concentrations of bulls after weaning. Mean eye muscle area (EMA) was greater in SUPP compared to CON bulls (68.5 ± 0.9 cm2 vs 65.2 ± 0.9 cm2; P < 0.05) and AISUPP bulls tended to have greater EMA (P = 0.06) than AICON bulls from 495 d of age. Thus when primiparous heifers experience moderate nutritional restriction during lactation, supplementation may have persistent effects upon increasing carcass muscle characteristics of bull progeny. • Protein supplementation of grazing primiparous beef heifers during lactation improves milk production and liveweight gain. • Lactational protein supplementation increases weaning weight of bull progeny, calfhood IGF-I and leptin concentrations. • Enhanced calfhood nutrition increases carcass muscling to 22 mo of age which can improve the sale value of breeding bulls. [ABSTRACT FROM AUTHOR]

There are no studies in the literature that comprehensively present the impact of factors related only to kosher slaughter on the content of minerals in beef. Therefore, learning the impact of such kosher determinants of beef as follows: no stunning during slaughter, cattle category, muscle, or the so‐called kosher treatment for mineral content in beef has an original character. In this connection, the aim of the research was a comprehensive analysis of the impact of kosher determinants (slaughter type, muscle, cattle category, and technological treatment) on the content of selected macro‐ and microelements in beef. On the content of minerals in muscles obtained from beef carcasses, the statistically significant (p < .05) impact was found in the case of slaughter type for such elements as: K, P, and Na. Higher content of phosphorus, potassium, and sodium was found in muscles of heifers and bulls from standard slaughter, compared with the amount of these elements determined in muscles of cattle from kosher slaughter. In turn, statistically significant (p < .05) impact of cattle sex was confirmed only in the case of iron and molybdenum content in beef. Higher amounts of these elements were determined in muscle from heifer carcasses (excluding the molybdenum content in MLT muscle of heifer carcasses from kosher slaughter). The process of koshering (soaking in brine) causes approximately 10‐fold increase in the amount of sodium in beef, regardless of the muscle or gender of cattle. The statistically significant impact of muscle was confirmed only in the case of zinc content. In the authors' own research, there was found no statistically significant impact of the interaction effects between the analyzed factors (S × G, S × M, G × M, and S × G × M) on the content of particular mineral components. [ABSTRACT FROM AUTHOR]

Our objective was to determine effects of genetic potential for residual feed intake (RFI) and pre-natal diet on post-natal growth and reproductive development of bulls. Twenty-five bull calves with a divergent potential for RFI were produced by mating purebred Angus heifers (60) categorised as high or low RFI and inseminated with semen from high or low RFI bulls. From 30 to 150 days of gestation, half the heifers (balanced for RFI across treatments) in each RFI category were fed to gain 0.7 or 0.5 kg/day (~100% and 75% of recommended feed intake; designated normal- and low-diet, respectively). Birthweights of bull calves (n = 25) did not differ significantly among treatment groups (P ≥ 0.1). However, there was a tendency (P < 0.1) for a maternal diet * time interaction for bull weights, with bulls from low pre-natal diet fed heifers growing faster between 10 and 16 months of age than bulls from normal pre-natal diet fed heifers. Furthermore, high-RFI bulls had a larger scrotal circumference (P < 0.01) and attained puberty (P < 0.05) earlier than low-RFI bulls. Other testes measures, including paired testes volume, epididymal sperm reserves, daily sperm production and total sperm production, were not significantly different among treatment groups (P ≥ 0.1). High RFI bulls tended (P < 0.1) to have better average sperm motility than low RFI bulls. However, sperm morphology, viability and chromatin damage were not different (P ≥ 0.1). In summary, young beef bulls with low RFI had smaller testis, delayed onset of puberty (~1.7 months) and tended to exhibit lower progressive motility compared with high RFI bulls. Pre-natal diet had no direct influence on male reproductive development, nor did it interact with RFI of bulls. As feed costs constitute 75% of production costs, recent efforts to balance production and costs incurred have increased the selection pressure for feed-efficient cattle. Despite numerous benefits, selection for residual feed intake (a common measure of feed efficiency) has negative effects on bull reproductive development but no interaction with the environment (pre-natal diet). In a cow-calf production sector, where fertility is crucial, a compromise between feed efficiency and fertility is required to improve profitability and sustainability of livestock production. [ABSTRACT FROM AUTHOR]

Highlights • Intact bulls perform better than heifers, especially on more energy-rich rations and swards. • Crossbreds give higher carcass yield compared to pure bred bulls, even if the crossbreds comprise 50% bulls and 50% heifers. • Carcass fatness and colour are ideal for premium cuts of heifers but generally not acceptable for premium cuts of the two bull groups when slaughtered from pasture. Abstract When crossbreeding with beef breeds in organic dairy herds, the use of non-sexed semen will results in both male and female offspring to be used for beef production. The objective of the present study was to compare growth and carcass characteristics of 15 Danish Holstein bull (HB) calves, 15 beef x Danish Holstein crossbred bull (CB) calves and 15 beef x Danish Holstein crossbred heifer (CH) calves reared under organic settings. As beef bred sire a high-merit bull of the Limousine breed was used. Furthermore, the study should generate knowledge which can support future organic beef production. Forty-five Spring-born calves were purchased at 10 private farms at approximately 20 days of age with an average initial body weight of 52.9, 58.2 and 56.1 (s.e.m. 2.6) kg for HB, CB and CH, respectively. Calves were housed indoors in groups of five until weaning off cows' milk at 3 months of age. Calves were gradually introduced to a grass-silage based ration from 3 to 4 months of age. From 4 to 7 months calves were kept on mixed grass pasture of ryegrass and white clover. From 7 to 13.5 months calves were housed indoor in groups of 5 and fed a mixed ration with low-moderate energy content. From 13.5 months of age, the established groups of 5 animals grazed in a rotational paddock system until slaughter at 17 months. There was no difference between HB, CB and CH in average daily gain (ADG) from birth to weaning, from weaning until turn-out and during pasture from 4 to 7 months. The ADG indoor from 7 to 13.5 months, and during pasture from 13.5 to 17 months differed between treatment groups. The CB had greater ADG than CH for both periods with HB being intermediate (P < 0.02–0.001). The ADG indoor from 7 to 13.5 months were 1.06, 1.10 and 0.97 (s.e.m. 0.02) kg d −1, and ADG during pasture from 13.5 months until slaughter were 0.88, 1.11, and 0.64 (s.e.m. 0.07) kg d −1 for HB, CB, and CH, respectively. Final body weights were heavier for CB, intermediate for HB, and lowest for CH (575, 534, and 480 (s.e.m. 12.1) kg, P < 0.01). Overall, ADG from arrival to slaughter was 21% higher for CB than CH (P < 0.001), and the average ADG of the combined heifer and bull crossbreds ((CB+CH)/2) was not different from that of HB. Crossbreeding improved EUROP conformation markedly in both CH (5.3) and CB (7.0) compared with HB (3.0) (P < 0.001), and carcass weight was 4% higher for crossbreds ((CB+CH)/2) compared with HB. There was no difference in EUROP fatness between HB and CB which was low (1.0–1.2), whereas CH had an acceptable fatness (2.9). Carcass lean:fat color (assessed using a Danish 1–5 scale) was high for the bulls (3.9–4.0) but acceptable for CH (3.3, P < 0.01). It is concluded that improvements in carcass conformation and carcass weight coupled with similar overall growth of the combined heifer and bull crossbreds support the efficiency of beef x Holstein crossbreds of both sexes compared with purebred Holstein bulls within an organic system with summer grazing. Furthermore, it proved difficult to finish intact bulls on pasture to fulfill a premium beef cut market that requires higher fatness and less dark meat color than obtained herein. [ABSTRACT FROM AUTHOR]

Many calves born on dairy farms are male, but little research to date has focused on the management of these calves. The objective of this study was to survey management practices of preweaned dairy bull calves and compare these practices with those used for heifer calves on the same operations. This study was conducted as part of the USDA National Animal Health Monitoring System Dairy 2014 study and included a sample of 42 operations from 10 states. On average, 2.4% of bull calves died before leaving the operation, with most operations selling bull calves before weaning (97.6%). Bull calves left the operation at an average age of 7.6 d (median = 4 d). Producers reported that 96.3% of bull calves received colostrum. Of bulls that were fed colostrum, the vast majority (95.4%) were hand-fed; the remaining calves received colostrum via a combination of hand-feeding and suckling (3.1%) or by suckling only (1.5%). In contrast, all heifer calves on those operations were only hand-fed colostrum. On average, bull calves received 3.1 L of colostrum at their first feeding at 4.3 h after birth compared with 2.9 L at 2.9 h after birth for heifer calves. In the first 24 h, bull and heifer calves received 4.8 and 5.5 L of colostrum, respectively. Only 21.4% of operations dehorned bull calves; in comparison, heifer calves were dehorned on 90.5% of operations. Few operations used analgesics or anesthetics when dehorning bull calves, whereas 28.9% of operations used anesthetics or analgesics when dehorning heifer calves. Overall, 27.8% of operations castrated bull calves. Of the operations that did castrate bulls, 70.0% used a band at an average age of 6.3 wk; the remaining 30% of operations used a knife at 14.7 wk of age on average. Few operations used analgesics or anesthetics when castrating. These results illustrate differences in the care of bull and heifer calves and suggest the need to improve education regarding recommended colostrum feeding and pain management practices in all calves regardless of sex. [ABSTRACT FROM AUTHOR]

Data collected from Australian Holstein cows that calved between 1995 and 2016 were used for estimating genetic parameters and genetic evaluation of gestation length (GL). Genetic parameters were estimated using a sire maternal grandsire model considering GL in heifers as correlated, but a different trait to adult cows and animal repeatability model. The key objective of this study was to assess if selective mating of bulls with short GL estimated breeding values (EBV) can help to modify calving patterns in predominantly pasture-based production systems and thereby contribute to the reduction of calving induction. The mean GL in heifers and adult cows was 280 and 281 d, respectively. The heritability of direct GL was 0.28 in heifers, which is slightly lower than in adult cows (0.36). The maternal heritability of GL was close to 0.04 in both heifer and adult cows. The genetic correlation between direct effects in heifers and adult cows was lower (0.88) than between maternal effects (0.94). A genetic evaluation model that considered heifer and adult cow data as the same trait in a repeatability animal model showed adequate variability in EBV for both direct and maternal GL. The genetic trend in direct GL EBV declined from 2005 in bulls and from 2006 in cows. Selective mating of bulls with short direct GL EBV showed that the GL and calving interval of their mates can be modified by up to 3.5 d for GL and 2.0 d for calving interval. Relative to parent average, the use of genotype data to calculate genomic EBV increased the reliability of EBV by up to 11% in validation bulls when daughter trait deviation of bulls with trait deviation of cows (11%) and deregressed breeding values (8%) were used as response variables. On average, for animals with only genotype data, the GL EBV can be predicted with about 50 to 60% reliability (expected) depending on the response variable (deregressed breeding values or daughter trait deviation and trait deviation) and the size of reference set. Overall, the results of this study show that calving patterns can be made tighter by selectively mating short GL EBV bulls to cows that do not become pregnant early in the mating season. Additionally, better reproductive management and the use of bulls with high female fertility EBV are still crucial for the success of a pasture-based dairy production system. [ABSTRACT FROM AUTHOR]

Background: To fulfill the increasing protein demand in Bangladesh, the government has started a programme to inspire the farmers for rearing Brahman as a beef breed. The objectives of the present investigation were to assess the performance of frozen semen of Brahman bulls with respect to conception rate and its associated influencing factors in Bangladesh. Methods: Data on AI performance, different factors and rate of conception were collected from 150 inseminated cows and heifers of Sadar upazila under Mymensingh district. The cows were inseminated by trained technician using frozen semen of a Brahman bull reared in Research Animal Farm of Department of Surgery and Obstetrics, Bangladesh Agricultural University, Mymensingh. Results: The overall conception rate was 55.3%. The conception rate in Holstein Friesian cross (68.9%) was significantly higher than that of Local (46%) cows (P<0.05). The conception rate in cows with BCS 2.5 - 3.0 was higher (60.7%) than that of BCS 2.0 and 3.5 -4.0 (42.0 and 41.7%, respectively) (P>0.05). Cows received insemination at parity 1-2 showed the highest conception rate (60.0%) and cows received insemination at parity 3-7 showed the lowest conception rate (47.0%) (P>0.05). Cows received insemination at 2 - <4 years age showed the highest conception rate (58.7%) and cows received insemination at 8 - 11 years age showed the lowest conception rate (41.2%) (P>0.05). AI done in cows yielding 6 -10 litres milk showed the highest conception rate (76.9%) and the lowest conception rate (42.5%) was found in cows yielding 1 - 2 litres milk (P<0.05). Cows inseminated at 19-24 hours interval between oestrus to AI had the highest conception rate (66.0%) and the lowest (38.1%) was in cows inseminated at =12 hours interval (P<0.05). The conception rate was the highest (69.2%) when insemination was done in Spring and the lowest (38.5%) was in rainy season (P>0.05). Conclusions: The overall conception rate was within acceptable level but further studies using more population of cows and semen donors are needed to confirm this result. [ABSTRACT FROM AUTHOR]

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The objective of this study was to evaluate relationships among feeding behaviors, off-test residual feed intake (RFI), and residual average daily gain (RADG) EPD for performance tested cattle. Eightyseven angus bulls and thirty-two angus heifers (n = 119) were fed a high forage diet consisting mainly of ground hay and corn silage for 57 days using the Vytelle feed system. The variables evaluated were time spent visiting the bunk, time with head down, number of visits, RFI, average DMI, DMI, RADG, ADG, and quadrant location of RFI and ADG. RFI and ADG are plotted for each individual animal, which places that individual into one of four quadrants (1 = Favorable RFI/Below average ADG, 2 = Favorable RFI/Above average ADG, 3 = Unfavorable RFI/Below average ADG, 4 = Unfavorable RFI/Above average ADG). The data were analyzed by gender, using non-parametric Spearman's Rho in JMP to determine variable relationships. A very strong positive correlation was observed in yearling bulls for the time spent with head down and the length of time spent at the bunk (0.8331, P < 0.0001). Also, a moderate correlation for the animals individual RFI and total number of visits (0.4924, P < 0.0001). A very strong negative correlation was observed for yearling bulls in the average amount consumed and the total number of visits to the bunk (-0.8380, P < 0.0001). Also, a weak negative correlation was observed in the animals individual RADG and RFI (-0.2777, P < 0.0001). Similarly, a strong positive correlation in yearling heifers was observed in head down and length of time spent at the bunk (0.9457, P < 0.0001). A strong negative correlation was observed in yearling heifers for the total number of visits and the average amount of feed consumed per each visit (-0.5293, P < 0.0018). Also, a moderate negative correlation in each animals individual RADG and RFI (-0.4822, 0.0052*). While a moderate positive correlation of individual animal RFI and the total number of visits was observed for the yearling bulls, the yearling heifers showed no significant correlation between the two. Our studies show that feeding behavior on a high forage diet is similar to that of behaviors shown on a high concentrate diet by others. Although there was a significant, but weak relationship between RFI and RADG, the strength of the relationship is such that one cannot be used predict the other and they are measuring different components of the animal's efficiency. [ABSTRACT FROM AUTHOR]

As double-muscled Belgian Blue (BB) and Piemontese (PIEM) breeds are heavily selected for different objectives (the former mainly for muscularity, the latter for ease of calving), the aim of this study was to compare sexual dimorphism in 56 crossbred young bulls and heifers obtained from dairy cows mated to bulls of the two beef breeds. Young PIEM- and BB-sired bulls had similar fattening performances and beef traits, although the BB crossbreds were slightly more muscular. Otherwise, the BB-sired heifers exceeded the PIEM-sired heifers in growth rate (1.12 vs. 0.98 kg/d), feed efficiency (0.129 vs. 0.121 kg/kg DM), increases in muscle scores (1.45 vs. 0.98 SEUROP scores) and carcass yield (0.612 vs. 0.605), but not in fatness, retail cut proportions and meat quality traits. Sexual dimorphism is, therefore, less distinct in BB than in PIEM crossbreds. In conclusion, BB sires are to be preferred for "product quality", and PIEM sires for "process quality", on account of welfare and ethical issues. • Piemontese and Belgian Blue double muscled (DBM) breeds are selected differently. • Belgian Blue is selected mainly for muscularity, Piemontese for calving ease. • Piemontese and Belgian Blue crossbred bulls exhibited similar fattening and beef traits. • Belgian Blue crossbred heifers outperformed the Piemontese ones for beef production. • Piemontese exhibit greater sexual dimorphism than Belgian Blue crossbred calves. [ABSTRACT FROM AUTHOR]

The study objective was to evaluate the Ready-Intermediate-Problem (RIP) replacement heifer evaluation matrix's ability to classify heifers into groups with differing reproductive outcomes. Beef heifers (n = 341) from six Kansas herds were classified according to RIP matrix guidelines and then exposed to AI breeding, bull breeding, or a combination of both as per the management plans for each participating herd. Following the breeding season the heifers were evaluated to determine pregnancy status, AI pregnancy status, days bred, and the number of 21 day cycles needed during the breeding season to become pregnant. After the breeding season, 298 (87%) of the heifers were pregnant, 204 (68%) of which became pregnant in the first 21 days of the breeding season. There was a significant interaction ( P = 0.01) in RIP classification and pregnancy by 21 day cycle. Ready classified heifers had a significantly greater risk of becoming pregnant after a single AI exposure ( P = 0.03) and in the first 21-day cycle ( P = 0.02) compared to Problem classified heifers, and significantly less risk of being non-pregnant at the end of the breeding season (P < 0.01) compared to Problem classified heifers. The RIP matrix can be useful for classifying heifers prior to the onset of the breeding season. Further research is needed to evaluate the matrix in other settings and populations of U.S. beef heifers as well as at different intervals between evaluation and the start of breeding season. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate and compare performance of body weight (BW) at slaughter, hot carcass weight (HCW) and dressing-out percentages (DP%) of bulls and heifers of different breeds. The data from heifers (84) and bulls (90) for sex; and for breeds of Simmental (58), Holstein (62) and their crosses (S×H) (54) were used as174 animals in total. BWs of each breed were 486.5, 485.6 and 462.2 for Holstein, Simmental and crosses, respectively. BWs of sex were 482 kg for both bulls and heifers. There were significant differences (P<0.05) in HCW and DP% between sexes. HCW of bulls and heifers were 257.68 and 245.58 kg, respectively. DP% for bulls and heifers were 53.68% and 51.15% respectively. There were significant differences (P<0.05) in HCW and DP% between breeds. HCW and DP% of Simmentals were greater than the other breeds while they were not significant (P>0.05) for Holstein and Crosses. There was no significant (P>0.05) breed and sex interaction for HCW and DP%. Simmental bulls and heifers were heavier than those of other breeds for HCW and DP%. It was observed that the performance of bulls and heifers of Crosses were better than Holstein bulls and heifers performance. [ABSTRACT FROM AUTHOR]

Dairy farmers can increase the number of dairy heifer calves born in their herd by using sexed semen. They can reduce the number of both dairy bull and heifer calves by using beef semen. Long before sexed semen became commercially available, it was believed that it would provide opportunities for increasing genetic level in both herds and populations. In this study, we studied the potential for increasing the genetic level of a herd by using beef semen in combination with sexed semen. We tested the hypothesis that the potential of increasing the genetic level and the overall net return would depend on herd management. To test this hypothesis, we simulated 7 scenarios using beef semen and sexed semen in 5 herds at different management levels. We combined the results of 2 stochastic simulation models, SimHerd and ADAM. SimHerd simulated the effects of the scenarios and management levels on economic outcomes (i.e., operational return) and on technical outcomes such as the parity distribution of the dams of heifer calves, but it disregarded genetic progress. The ADAM model quantified genetic level by using the dams' parity distributions and the frequency of sexed and beef semen to estimate genetic return per year. We calculated the annual net return per slot as the sum of the operational return and the genetic return, divided by the total number of slots. Net return increased up to €18 per slot when using sexed semen in 75% genetically superior heifers and beef semen in 70% genetically inferior, multiparous cows. The assumed reliability of selection was 0.84. These findings were for a herd with overall high management for reproductive performance, longevity, and calf survival. The same breeding strategy reduced net return by €55 per slot when management levels were average. The main reason for the large reduction in net return was the heifer shortage that arose in this scenario. Our hypothesis that the potential for beef semen to increase genetic level would be herd-specific was supported. None of the scenarios were profitable under Danish circumstances when the value of the increased genetic level was not included. A comparable improvement in genetic level could be realized by selectively selling dairy heifer calves rather than using beef semen. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Animal Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to evaluate the muscle fibre diameter of bulls (n = 136), heifers (n = 38) and steers (n = 18). The influence of age at slaughter, weight at slaughter, net daily weight gain, SEUROP meatiness and SEUROP fatness on the muscle fibre diameter was observed. The group of animals included Czech Red Pied and its crossbreeds (F1) with the specialized meat breeds (Charolais and Galloway), further crossbreeds of hybrid bulls. Bulls were slaughtered at an average age of 587 days and average weight of 610 kg. The average age of heifers was 644 days and average weight at slaughter was 550 kg. The highest average age was that of steers (689 days) and they were fattened to the average weight of 610 kg. The sample of musculus longissimus lumborum et thoracis (m.l.th.) was used for the ana­ly­ses. The results showed that the muscle fibres were stronger in diameter in the negatively selected (culled) heifers (p > 0.01) as compared to the category of bulls and steers. Apart from sex we also analysed the effect of age at slaughter of the individual animal categories on the fibre diameter. We discovered that the diameter of the fibre increased with age. The fibre diameter of bulls of up to 530 days of age was 37.86 µm and at the age of more than 601 days it was 39.81 µm. The diameter of the muscle fibres was also affected by the pre-slaughter weight. At lower weights the fibres of all categories of cattle were finer. Of growth factors affecting the fibre diameter we selected the net weight gain which is the general indicator of the life-long growth intensity and carcass yield. The fibre diameter in bulls and steers increased insignificantly (p > 0.05) with increasing net weight gains. We also analysed the effect of the SEUROP classification of cattle carcasses and discovered a stronger correlation between the dia­me­ter of muscle fibres and meatiness compared to the classification of fatness of the carcasses.

The main aim of the study was the evaluation of the quality of carcasses of bulls (n = 196), heifers (n = 83), steers (n = 39) and cows (n = 61) by morphometric analysis and cutting of right parts of carcas­ses. All categories under study were bred on the farm in Moravia and East Bohemia. Bulls and hei­fers were slaughtered at average age 661 days, whereas their average age was 668 ± 52 kg. Cows were slaughtered at the age from 2.5 to 8 years, while their average weight was 573 ± 121 kg. Statistically highly significant differences (p < 0.01) were found between length and low-level size of body of all categories under study. The best meatiness of rump was found in steers. Girth spiral round in steers was 173 cm. The highest share of meat was found in bulls (77%). On the other hand in this category was found the lowest share of bone (21.8 %). The highest share of meat of the first quality was found in heifers (30.2 %). The shares of meat of heifers and steers were comparable and ranged between 76.0 and 75.8%. The share of bones in steers was 22.7%. In fine it is possible to state that the cows have comparable share of meat to bulls, however on the other hand the cows meat have the worse nutritional and culinary qualities.

The objective of the present study was to determine growth and carcass traits of beef breed bulls and heifers in the Finnish beef cattle population. The data collected from Finnish slaughterhouses included observations of 6323 and 2385 Hereford (bulls and heifers, respectively), 4421 and 1794 Charolais, 4335 and 1951 Limousin, 4068 and 1692 Aberdeen Angus, 2151 and 774 Simmental, 344 and 147 Blonde d’Aquitaine animals. For estimating valuable cuttings, a separate dataset including in total 1112 bulls and 260 heifers was also collected. Significant breed differences were observed in growth performance, carcass traits and retail product yield. The later maturing, Continental beef breeds seem to reach higher carcass gains, produce less fat and have more valuable cuts than the earlier maturing British beef breeds. The later maturing beef breeds tend to have carcass traits that suit well in the Finnish beef production system.

Telomeres are comprised of G-rich nucleotide sequences (5'-TTAGGG-3') at the chromosome termini that are responsible for protecting chromosomes; however, attrition of these sequences has been observed due to aging and stress. The purpose of this study was to compare telomere length (TL) in control and prenatally stressed (PNS) calves. Mature Brahman cows inseminated to a single Brahman sire in 2018 were assigned to be either Control (n=35; not transported) or PNS (n=37; 2 h of transportation at 60, 80, 100, 120, and 140±5 d of gestation). Jugular blood samples were obtained by venipuncture from 10 Control (5 bulls and 5 heifers) and 10 PNS (5 bulls and 5 heifers) calves at 25±2 d of age. Peripheral leukocytes were isolated and genomic DNA was extracted utilizing silicone membrane spin column kits. The relative quantity of telomere products, which is proportional to the average TL, was determined by multiplex quantitative PCR analysis using the ratio of bovine telomere and ß-globulin DNA (T/S ratio). An absolute standard of bovine telomere (1012-107 dilution series) and ß-globulin (109-104 dilution series) genes was utilized to produce relative copy number. All samples were processed in triplicate and samples were included if the triplicate Cq difference was less than 0.25 cycles. Data were analyzed using ANOVA. TL differed by sex (P< 0.03; bulls 11,959±211; heifers 12,850±366) and treatment (P< 0.02; Control 12,895±278; PNS 11,913±303). There was not an interaction of sex and treatment (P >0.43) although TL of Control heifers (13,482±396) exceeded the TL of PNS bulls (11,609±348). These observations of fewer copies of telomere sequences suggest an influence of sex on TL within 1 month of age; and, that prenatal transportation stress may increase attrition of telomeres in cattle. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effects of alternative-measurements of body weight and DMI used to evaluate residual feed intake (RFI). Weaning weight (WW), ADG, and DMI were recorded on 970 growing purebred Charolais bulls (n = 519) and heifers (n = 451) and 153 Red Angus growing steers (n = 69) and heifers (n = 84) using a GrowSafe (GrowSafe, Airdrie, Alberta, Canada) system. Averages of individual DMI were calculated in 10-d increments and compared to the overall DMI to identify the magnitude of the errors associated with measuring DMI. These incremental measurements were also used in calculation of RFI, computed from the linear regression of DMI on ADG and midtest body weight0.75 (MMWT). RFI_ Regress was calculated using ADG_Regress (ADG calculated as the response of BW gain and DOF) and MMWT_PWG (metabolic midweight calculated throughout the postweaning gain test), considered the control in Red Angus. A similar calculation served as control for Charolais; RFI was calculated using 2-d consecutive start and finish weights (RFI_ Calc). The RFI weaning weight (RFI_WW) was calculated using ADG_WW (ADG from weaning till the final out weight of the postweaning gain test) and MMWT_WW, calculated similarly. Overall average estimated DMI was highly correlated to the measurements derived over shorter periods, with 10 d being the least correlated and 60 d being the most correlated. The ADG_Calc (calculated using 2-d consecutive start and finish weight/DOF) and ADG_WW were highly correlated in Charolais. The ADG_Regress and ADG_Calc were highly correlated, and ADG_Regress and ADG_WW were moderately correlated in Red Angus. The control measures of RFI were highly correlated with the RFI_WW in Charolais and Red Angus. The outcomes of including abbreviated period DMI in the model with the weaning weight gain measurements showed that the model using 10 d of intake (RFI WW_10) was the least correlated with the control measures. The model with 60 d of intake had the largest correlation with the control measures. The fewest measured intake days coupled with the weaning weight values providing acceptable predictive value was RFI_WW_40, being highly correlated with the control measures. As established in the literature, at least 70 d is required to accurately measure ADG. However, we conclude that a shorter period, possibly as few as 40 d is needed to accurately estimate DMI for a reliable calculation of RFI. [ABSTRACT FROM AUTHOR]

In prepubertal bulls and heifers of dairy and beef breeds, puberty can be induced to occur earlier than typical with targeted high-energy diets due to precocious activation of the endocrine mechanisms that regulate puberty. Precocious activation of puberty in bulls intended for use in the AI industry has the potential to hasten and perhaps increase sperm production. It was hypothesized that feeding bulls a high-energy diet beginning at 8 wk of age would advance the prepubertal rise in LH and lead to advanced testicular maturation and age at puberty. From 58 to 230 ± 0.3 d of age, Holstein bulls received either a high-energy diet (HE; n = 9; targeted ADG 1.5 kg/d) or a control diet (CONT; n = 10; targeted ADG 0.75 kg/d). Thereafter, all bulls were fed a similar diet. The HE treatment increased LH secretion at 125 d of age, testosterone concentrations from 181 to 210 d, and scrotal circumference (SC) from 146 to 360 d of age relative to the CONT treatment. Beginning at 241 ± 5 d of age, semen collection (artificial vagina) was attempted every 14 d in bulls from the HE (n = 8) and CONT (n = 7) treatment until each bull attained puberty (ejaculate containing 50 × 106 spermatozoa with 10% motility). To assess semen production as mature bulls, semen was collected thrice weekly beginning at 541 ± 5 d of age until slaughter at 569 ± 5 d of age. After slaughter, epididymal and testicular measurements were collected and testicular tissue was fixed to determine seminiferous tubule diameter. Age at puberty did not differ between treatments (310 ± 35 d). Although testis and epididymal weight and testis volume were greater (P < 0.05) in the HE than the CONT treatment, sperm production of mature bulls did not differ between treatments. Diameter of seminiferous tubules also did not differ between treatments. We conclude that the HE advanced aspects of sexual maturation and increased testes size, but this was not reflected in hastened puberty or sperm production in the present experiment. [ABSTRACT FROM AUTHOR]

Flexible software was designed to replace the current animal model programs used for national genetic evaluations. Model improvements included (1) multi-trait processing, (2) multiple fixed class and regression variables, (3) differing models for different traits, (4) random regressions, and (5) foreign data included using pseudo-records. Computational improvements included (6) parallel processing, (7) renumbering class variables to equation numbers within the program so that estimated effects are output with original identification numbers, and (8) reliability computed within the same program. When applied to 3 fertility traits of 27,971,895 cows and heifers, the new model used daughter pregnancy rate as a correlated trait to improve heifer and cow conception rate evaluations for older animals and in herd-years where records are missing, and also added information from crossbreds. When applied to 7 traits and 76,846,327 lactation records of 30,064,300 cows, gains in accuracy were small for yield and somatic cell score, moderate for daughter pregnancy rate, and larger for productive life for recent bulls compared with single-trait evaluations. For very old bulls, multi-trait gains were also large for protein because lactation records were available only for milk and fat. Multi-trait productive life was computed with exact rather than approximate methods; however, correlated information from conformation was excluded, reducing advantages of the new model over the previous software. Estimates of breed differences, inbreeding depression, and heterosis were similar to previous estimates; new estimates were obtained for conception rates. Predictions were compared by truncating 4 yr of data, and genetic trend validation was applied to all breed-trait combinations. The estimates of trend account for increases in inbreeding across time. Incorporation of foreign data gave correlations above 0.98 for new with previous evaluations of foreign Holstein bulls, but lower for other breeds. The 7-trait model required 35 GB of memory and 3 d to converge using 7 processors. The new software was implemented for fertility traits in 2013 and is scheduled for implementation with yield, somatic cell score, and productive life in 2014. Further revision of the models and software may be needed in the near future to account for genomic preselection. [ABSTRACT FROM AUTHOR]