Hereford Bull Calves Research Articles

Reducing the modifying impact of the ecological factor at breeding value assessment of Hereford bull calves taking into account phenotype and complex of genes GH and GDF5

The objective assessment of beef cattle genetic potential is a priority task of beef cattle breeding intensification. The purpose of the study was to test a method for reducing the modifying effect of ecological factor in assessing the breeding value of Hereford bulls based on combined selection, taking into account the phenotype assessment and genotyping by GH and GDF5 genes. For this purpose, the bull calves were tested according to productivity in two variants: 1) setting and selection of young cattle for control cultivation on the basis of phenotype (traditional assessment); 2) traditional selection was supplemented by genotyping assay for the complex of GH and GDF5 genes. The individuals with desired allelic profile (genotypes VV and VL of GH gene and genotypes TT and TC of GDF5 gene) showed increased weight gain intensity relative to their herd mates. The analysis of body weight repeatability data at different stages of ontogenesis shows that the selection of carriers of desirable alleles for the gene complex increases the accuracy of high-priced animal selection. Thus, in order to determine the genetic potential of Hereford bull calves more objectively and minimizing the ecological impact on breeding value, it is advisable to use a combined approach to selection that unites the assessment of the phenotype of young cattle and the genotyping of animals taking into account the complex of genes GH and GDF5.

The effect of different suckling feeding modes on the growth and development of calves in postnatal ontogenesis

One of the key areas of development of the cattle breeding industry in Russia is the creation of effective technological methods. They allow to carry out the improvement and establishment of new resource-saving systems for breeding young animals at an accelerated pace. It is essential to meet the modern requirements of meat production as an ecologically safe product. The aim of the research was to enhance the fattening qualities of Hereford bull calves while using mode-setting suckling of various ratios as an element of resource saving. The study was performed on "SAVA-Agro-Yapryk" OOO of the Tuymazinsky district of the Republic of Bashkortostan. The determination of the efficiency of the use of free and mode-setting suckling of various ratios made it possible to identify an effective method of raising young meat cattle. A three-fold mode suckling is used with separate keeping of young animals and mother cows. This makes it possible to keep the optimal microclimate parameters in the calf house, contributes to the rapid early adaptation of calves to the consumption of coarse feed and concentrates. It has a positive effect on the growth and development of calves and their meat productivity at the age of 18 months according to the parameters of removable fat mass, carcass mass and interior fat mass. All this promotes an increase in the sale of beef and an improvement in the level of production profitability to 13.93%.

Effects of Leptin Gene Polymorphism on Beef Cattle Performance

Livestock specialized cattle breeds combining high energy for both growth and fattening performance are successfully used for high-quality beef production. The use of DNA markers as the additional criteria for sampling and mating the animals allows us to increase the efficiency of selection processes along with improving the meat characteristics of cattle. The objective of the survey was to estimate the effects of leptin gene polymorphism on the growth rates of youngstock and the product quality of beef cattle. The practical science experiment was carried out in 2014–2017. The fattening Hereford and Limousin bull calves (114 and 111 animals, respectively) were genotyped with the technique of polymerase chain reaction (PCR) and subsequent PCR-restriction fragment-length polymorphism analysis (SNP LEP-A422B). A similar genotype distribution among the animals was revealed. Homozygous genotype LEPAA (47.34% and 52.25%, respectively) and allele LEP4 (frequencies of occurrence are 0.68 and 0.71, respectively) are more frequent. The liveweight in both cattle breeds with genotype LEPAA tended to increase at the ages of 8, 12, 16, and 20 months. In addition, an insignificant predominance in body measurements used to assess the proportions of their body parts was ascertained. The analysis of the body conformation indices could indicate harmonious animal development and prove the well-expressed beef forms in the youngstock of all the genotypes for the leptin gene. The postslaughter assessment allowed us to reveal the tendency to increasing the values for the preslaughter liveweight, the hot carcass weight, and the slaughter weight. In addition, the increased carcass yield was recorded in the Hereford bull calves with genotype LEPAA. The surveys ascertained a significant relationship between the analyzed polymorphism and the increases in the internal crude fat weight and the fat yield in the carcasses of bull calves with genotypes LEPAB and LEPBB. The analysis of the morphological composition of Hereford bull calf carcasses revealed a significant relationship between genotype LEPBB and fat contents. Therefore, SNP LEP-A422B genotyping may be used in Hereford and Limousin cattle breeding to improve the meat quality parameters.

Beef for baby food from bulls and castrates

The research was conducted to compare bulls and castrates in relation to the morphological composition of carcasses, the yield of beef suitable for the production of baby food products, and the quality and safety of raw meat. The research was based on the results of monitoring the safety of the environment, feed, and meat raw materials during the growing and fattening of steers with a meat productivity direction. The pre-slaughter weight and the yield of lean beef of 16-month-old Hereford bull-calves are higher in comparison with castrated animals of the same age, by 6.4 and 1 %, respectively. The muscle tissue of castrates contained 11.5 % of fat, and bulls 9.7 %. The protein content in the longest muscle of bulls was 19.8 %, and in castrates-17.0. The amount of fat beef that is not suitable for baby food is higher in castrate carcasses by 4.7 % compared to bull calves. A high protein quality index of the longest muscle of bulls (6.5) indicates a higher biological value of beef compared to meat from castrates (4.1). In terms of the content of residual amounts of pesticides, toxic elements, and antibiotics, the meat of castrates and bulls of the Hereford breed had no significant differences.

Genotypical features of the exterior development of Hereford bull-calves

An analysis of previous years shows that there is a gradual increase in the rate of breeding and pedigree work, its intensification, which is caused primarily by the implementation of new methods of biotechnology and population genetics. In this regard, the improvement and development of new criteria for cow evaluation taking into account created highly productive lines, types, and populations are relevant for science and practice. There was carried out scientific and economic research in order to characterize the main indicators of the breeding value of cows that belong to the created hornless Ural-type Hereford breed of domestic breeding. The influence of these indicators on the formation of the productivity of bull-calf progenies fell under the characterization as well. There were formed five groups of full-aged cows (5-8 years) different in productive qualities to determine the influence of the productive value of mother cows on the pedigree and productive qualities of progenies. Cows of all groups were inseminated by the deep-frozen seed of Hereford bull of the “elite-record” class produced by Golub 4168. Five groups of experimental bull-calves were formed by the method of groups-analogs from the resulting progeny. The analysis of weight and linear growth of the progeny bull-calves showed that all the animals normally developed being characterized with the general patterns of ontogenesis. At the same time, bull-calf progenies of cows different in productive value were inherent in some features - the average live weight of bulls of group III was larger than those of its peers from groups I, II, IV, and V by 27.4 kg (6.3 %, P>0.95), 64.1 kg (16.1 %, P>0.999), 28.9 kg (6.6 %, P>0.95), and 47.4 kg (11.4 %, P>0.999), respectively.

Effect of GH and DGAT1 gene polymorphism on feeding qualities of bull calves

The aim of this paper is to study effects of GH and DGAT1 gene polymorphisms on feeding qualities of Hereford and Limousin bull calves bred in conditions of the Cis-Ural steppe zone. SNPs of genes GH and DGAT1 are investigated by polymerase chain reaction (PCR) and DNA restriction fragment length polymorphism (RFLP). The studied population of animals was assessed by defining the allele frequency and animal genotype occurrence for the studied gene SNPs, indicators of the actual and expected heterozygosity, and Pearson’s test. A study of polymorphism C214G of gene GH revealed that genotype LL prevails in Hereford and Limousin animals, 47.37 and 57.7%, respectively, while frequency of allele L is higher in Limousin bull calves (0.731). A study of polymorphism K232A of gene DGAT1 gene in both the populations showed absence of genotypes AA, which can be related to the low number of the studied animals. Expected heterozygosity indicators of gene GH are higher than the observed ones, and the observed heterozygosity is higher for DGAT1. The number of efficient alleles for the studied genes is higher for Hereford bull calves. In general, according to Pearson’s test, both the studied populations are in equilibrium. There is a significant effect of GH gene polymorphism on live weight gain rates at the end of sagination and total and average daily weight gains during animal raising.

Effects of polymorphism in TG5 and LEP genes on meat productivity of Hereford and Limousin bull calves

The effects of polymorphism in the TG5 and LEP genes on meat productivity of Hereford and Limousin bull calves have been studied under the environmental conditions in the pre-Ural steppe zone. A significant dominance of the TG5C and LepA alleles is determined in the animals of both breeds; the distributions of frequencies of the genotypes for the TG5 gene are similar in character. The most common genotypes are TG5CC and TG5CT. The genotype frequency analysis indicates the considerable genetic potential of the animals for palatability and the nutritional values of meat, which is specified by the relatively high proportions of the TG5T allele and the desirableTG5TT genotype. The breed differences in the frequencies of genotypes for the LEP gene were ascertained as follows: the LEPAA genotype is predominant in the Hereford bull calves, while the relatively useful LEPAB genotype prevails in the Limousin bull calves. No significant relationship between the target TG5 and LEP SNP-genes and the animal growth rates was revealed.

The content of lead in some organs and tissues of Hereford bull-calves

The content of lead in muscles, liver, spleen and testicles is studied in Hereford bulls, aged 18 months. Selectivity of Pb accumulation is identified in organs and tissues. Pb level in organs and tissues may be ranged as follows: liver>spleen>muscles>testicles in the ratio 4.7: 4.4: 1.2: 1. It is shown that the increased concentration of lead in testicles decreases the content of vitamins. Some biological indexes of blood serum are indicators of Pb level in muscles and liver.

Effects of treatment with LH releasing hormone before the early increase in LH secretion on endocrine and reproductive development in bull calves.

Between 6 and 20 weeks of age an early increase in LH secretion has been reported in Hereford bull calves. Delaying this early increase in LH secretion delays testicular development. This study was designed to determine whether a premature increase in LH secretion during the early postnatal period enhances testicular development. Ten age- and body weight-matched Hereford bull calves were divided into two groups. One group (n = 5) received 200 ng LH releasing hormone (LHRH) i.v. every 2 h for 14 days, between 4 and 6 weeks of age. On the basis of blood samples taken every 15 min for 10 h, mean serum LH and testosterone concentrations and LH pulse frequency were increased by LHRH treatment (P < 0.05). Serum concentrations of FSH were not significantly influenced by treatment (P > 0.05). In treated animals at 24 weeks of age, mean serum testosterone concentrations and LH pulse amplitude were increased (P < 0.05). The concentrations of spermatozoa in electroejeculates collected at 52 weeks of age were greater in LHRH-treated compared with control calves. Testicular growth was enhanced by LHRH treatment and histological evaluation of the testis at 54 weeks of age showed increased spermatogenesis and also larger numbers of Sertoli cells per tubule cross-section as a result of LHRH treatment. We conclude that treatment with LHRH before the early increase in LH secretion altered testicular development and suggest that the early increase in LH secretion in bull calves may be critical for initiating and regulating the progression of reproductive maturation.

Effect of inhibition of increased gonadotrophin secretion before 20 weeks of age in bull calves on testicular development.

In bull calves serum concentrations of LH, FSH, and to a lesser extent testosterone, are increased transiently, between 6 and 20 weeks of age. The function of gonadotrophin and testosterone secretion in this period of growth and development was tested by injecting five Hereford bull calves with a GnRH agonist (15 mg Leuprolide acetate) i.m. at 6, 10 and 14 weeks of age; five vehicle treated calves acted as controls. On the basis of blood samples taken every 15 min for 10 h, at 12 weeks of age, mean serum concentrations of LH, FSH and testosterone and LH and FSH pulse frequency and amplitude were decreased (P < 0.05) by Leuprolide acetate. At 24 weeks of age, mean serum concentrations of LH, and LH and FSH pulse frequency in Leuprolide acetate treated calves exceeded (P < 0.05) that seen in control calves. On the basis of blood samples taken every other week, treatment with Leuprolide acetate decreased mean serum concentrations of FSH and testosterone at 14, 16 and 18 weeks of age compared with control calves and delayed the peak of the early increase in LH secretion from 20 to 24 weeks of age (P < 0.05). Scrotal circumference between 22 and 50 weeks of age, pixel units from ultrasound images of the testes, testis mass at castration at 50 weeks of age, and numbers of spermatids and pachytene spermatocytes were all lower in Leuprolide treated calves than in controls. A transient increase in secretion of LH, FSH and testosterone in young bull calves before 20 weeks of age may, therefore, be a critical step in the initiation and timing of testicular development in bull calves.

Phenotypic and genetic variation in body weight, food intake and energy utilisation in Hereford cattle I. Performance test results

From body weight, food intake and carcass composition data on 542 Hereford bull calves, measuredfrom 200 to 400 days, several traits relating to the efficiency of beef cattle production were derived and analysed. Traits included body weight at various ages, weight gain, predicted carcass lean content, lean growth rate, food intake, food conversion ratio, lean food conversion ratio, food intake in relation to metabolic body weight, energy required for protein and fat deposition, and predicted maintenance expenditure. Maintenance expenditure and the costs of fat and protein deposition were calculated by two means,firstly from allometric equations describing fat and protein accretion, and secondly from a multiple regression of food intake on weight gain and predicted carcass lean content. The two methods gave different mean values, but the correlations between traits calculated by the two methods were almost all 1.00. Exponents for metabolic body weight derived from the two methods were 0.738 and 0.758, respectively. Genetic parameters were calculated using multivariate Restricted Maximum Likelihood techniques.Body weight, carcass composition and traits combining these measurements were moderately to strongly inherited whereas traits related to food intake and efficiency were weakly to moderately inherited. Energy used to deposit fat and lean was more strongly inherited than predicted maintenance expenditure, and these traits were genetically almost uncorrelated. Maintenance energy expenditure showed no genetic relationship with predicted carcass lean content. Efficiency and predicted maintenance expenditure were favourably correlated.

Phenotypic and genetic variation in body weight, food intake and energy utilisation in Hereford cattle II. Effects of age and length of performance test

The effects of length of test, age when evaluations are made, and correction of data for body weightat the start of test on genetic and phenotypic parameters describing performance test results in beef cattle were studied. The data consisted of body weight, food intake and carcass composition measurements on 542 Hereford bull calves, from 200 to 400 days of age. The traits studied included weights at various ages, weight gain, lean growth rate, food intake, food conversion ratio, lean food conversion ratio, food intake in relation to metabolic body weight, energy required for protein and fat deposition, and predicted maintenance expenditure. Traits were derived for the whole test as well as for part test periods of 200–300 days and 300–400 days. Heritabilities for all traits, except those describing weight at a given age, were lower for the 300–400-day period than for either the 200–300-day period or the whole test. Correlations, however, were higher between whole test and 300–400-day traits than between whole test and 200–300-day traits. Phenotypic correlations between the same trait measured in the two-part test period were very low and much lower than the genetic correlations. Corrections for body weight at the start of test had only a trivial effect on the heritabilities of all traits, the relationships between traits and potential genetic progress in traits measured during the test.

BLOOD COMPOSITION IN HEREFORD AND ANGUS BULLS FROM LINES SELECTED FOR RAPID GROWTH ON HIGH-ENERGY OR LOW-ENERGY DIETS

Angus and Hereford bull calves were obtained from lines of cattle selected for 18 yr for rapid post-weaning gain on high-energy or low-energy diets. After weaning they were given a common diet consisting of 70% barley-based concentrate and 30% roughage. Bulls whose ancestors were selected on the high-energy diet had lower levels of cholesterol and albumin in the blood than bulls whose ancestors were selected on the low-energy diet. Blood insulin, growth hormone and energy substrates were not affected by differences in the nature of the selection diets and this accords with absence of effect of selection diet on rate, efficiency or composition of gain. The significance of the selection effects on cholesterol and albumin levels in blood is unknown. Key words: Angus, Hereford, bulls, blood, composition, selection

Effect of zeranol on sexual development of crossbred bulls.

Three groups of 1/2 Simmental X 1/4 Brahman X 1/4 Hereford bull calves were used during two different years to study effects of zeranol on sexual development. At 154 d of age, half the calves were implanted with 36 mg zeranol and half, not implanted, served as controls. Implanted calves were reimplanted at 90-d intervals throughout the trial (9 mo) each year. Trial 1 was conducted with 24 calves and Trial 2 was conducted the following year with 10 bulls. Twenty-four days after weaning (200 d of age) and at 28-d intervals thereafter, bulls in drylot in Trial 1 were weighted, scrotal circumference (SC) was measured and an ejaculate of semen was collected by electroejaculation to determine puberty. At these times, bulls were given 200 micrograms of GnRH i.m. and blood was collected at 0, 1, 2, 3, 4 and 5 h after GnRH. Serum concentrations of LH and testosterone (TEST) were determined. At slaughter, testis weight, length and circumference and pubertal status were recorded. Bulls implanted with zeranol had smaller SC than control bulls during the entire 9-mo period (P less than .0001). More control bulls reached puberty than did implanted bulls (82.4 vs 23.5%, respectively; P less than .001). Control bulls had larger testis measurements at slaughter (P less than .0001). Implants did not alter total weight gain or ADG (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of rearing environment on sexual behavior of young beef bulls.

Fifty-eight Polled Hereford bull calves were weaned at an average age of 196 d. They were penned individually after weaning and contact was limited to fenceline exposure to bulls in adjacent pens, except when grouped for weighing every 28 d. Six months after weaning they were allotted to one of the following 10-wk rearing treatments: 1) individually penned; 2) individually penned, but exposed to a heifer in estrus for 30 min every 2 wk; 3) group penned; 4) group penned, but each bull exposed to a heifer in estrus for 30 min every 2 wk. The week after allotment was designated wk 0. All 58 bulls, penned together after wk 12, had single-bull mating tests during wk 10, 22 and 32 and multi-bull mating tests during wk 12, 24 and 34. Mean serving capacity and mean serving efficiency were both greater (P less than .05) for individually-penned bulls than for group-penned bulls during the first single-bull and the first multi-bull mating test. No significant serving-capacity differences were present in subsequent single-bull or multi-bull mating tests, but serving efficiency was greater (P less than .05) for group-penned bulls in all subsequent tests, except the last multi-bull mating test. Mean serving capacity was greater (P less than .05), as was mean serving efficiency (P less than .01), for bulls in single-bull mating tests than for those in multi-bull tests. Exposure to heifers during rearing did not affect libido or mating ability.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma growth hormone, prolactin and thyrotropin secretory patterns in Hereford and Simmental calves.

An experiment was conducted to test the hypothesis that bull calves of a larger, faster growing breed of cattle exhibit greater secretory activity of anabolic pituitary hormones than bull calves of a smaller, slower growing breed. Calves of both breeds were raised under similar conditions and maintained on the same diet for approximately 4 weeks before the blood sampling period. Simmental bull calves had higher (P less than .01) average daily gains and a heavier (P less than .01) mean body weight than Hereford bull calves. Overall plasma growth hormone (GH) concentrations were higher (P less than .01) in Simmental bull calves than in Hereford bull calves. Mean baseline GH was also higher (P less than .05) in Simmentals. Overall and baseline concentrations of prolactin (PRL) were similar for both breeds. Mean amplitude of PRL secretory spikes was higher (P less than .05) for Simmental than for Hereford bull calves. There was no breed effect on any variable of thyrotropin secretion. These data suggest that representatives of a larger, faster growing breed of cattle (Simmental) exhibit greater secretory activity of GH and PRL than do representatives of a smaller, slower growing breed (Hereford).

Estimates of Heritabilities and Correlations for Production Characters of Angus and Hereford Calves

Field records of purebred Angus bull and heifer calves and Hereford bull calves were analyzed to estimate heritabilities of and correlations among five growth characters; birth, weaning and final test weights and preweaning and postweaning average daily gains (ADG). Hereford heifer calves were included in a separate analysis of weaning weight by itself with a greater number of records. Heritability estimates in all of the analyses where both sexes within the breed were included were consistendy higher for bulls than for heifers. The Angus estimates for sexes pooled, bulls and heifers, respectively, were .40, .49 and .36 for birth weight; .38, .42 and .22 for preweaning ADG; .35, .37 and .21 for weaning weight; .30, .47 and .44 for postweaning ADG; and .36, .43 and .24 for final test weight. The Hereford bull estimates for the same respective characters were .54, .41, .43, .26 and .65. The analysis of Hereford weaning weight for both sexes yielded heritability estimates of .31 for sexes pooled, .36 for bull calves and .30 for heifers. Genetic and phenotypic correlations among characters within each breed and sex and with sexes pooled were estimated. Within-sex genetic correlation estimates were moderate to high (.37 to .97) with the following exceptions: Hereford bulls, birth weight-preweaning ADG = .17; Angus bulls, preweaning ADG-postweaning ADG = .19 and weaning weight-postweaning ADG = .18; and Angus heifers, birth weight-postweaning ADG = .00, preweaning ADG-postweaning ADG = -.11, and weaning weight-postweaning ADG = -.18. The phenotypic correlations were, in general, smaller than the genetic correlations The results supported estimates of genetic parameters from experiment station data and indicated that progress can be expected when selecting for one or more of these characters and that correlated responses in the other characters should be anticipated.

ENVIRONMENTAL FACTORS AFFECTING PRE- AND POST-WEANING TRAITS OF HEREFORD BULL CALVES

Records of 1372 Hereford bull calves tested under the Ontario Advance Registry Policy for beef cattle were analyzed to estimate the effect of age of dam, season of birth, and year of birth on 240-day (weaning) weight, average daily gain (postweaning), and weight per day of age.Two- and three-year-old cows weaned calves 34.3 and 13.5 lb below the population average. As age of cow increased from 4 to 8 years little change occurred; however, older cows weaned calves 13.5 lb above average. Weight per day of age showed a trend identical with weaning weight. Age of cow did not influence postweaning growth. Calves born during the fall and winter weaned slightly heavier than those born during the spring and summer. Although certain trends were evident and differences were significant, less than 10% of the total sum of squares were partitioned by the combined effect of age of dam, season, and year. An appropriate set of adjustment factors based on the analysis would be provided by the addition of 40 and 15 lb respectively to the weaning weights of calves from 2- and 3-year-old cows, and of.12 lb to the weight per day of age of calves from 2-year-old cows. It is postulated that under good environment calves from older cows will grow as well as their contemporaries from cows of a middle-age group.