Non-synonymous mutations mapped to chromosome X associated with andrological and growth traits in beef cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estimation methods of non-additive effects for characteristics of weight and scrotal circumference in crossbred beef cattle

The objective of this study was to investigate, in a population of crossbred cattle, the obtainment of the non-additive genetic effects for the characteristics weight at 205 and 390 days and scrotal circumference, and to evaluate the consideration of these effects in the prediction of breeding values of sires using different estimation methodologies. In method 1, the data were pre-adjusted for the non-additive effects obtained by least squares means method in a model that considered the direct additive, maternal and non-additive fixed genetic effects, the direct and total maternal heterozygosities, and epistasis. In method 2, the non-additive effects were considered covariates in genetic model. Genetic values for adjusted and non-adjusted data were predicted considering additive direct and maternal effects, and for weight at 205 days, also the permanent environmental effect, as random effects in the model. The breeding values of the categories of sires considered for the weight characteristic at 205 days were organized in files, in order to verify alterations in the magnitude of the predictions and ranking of animals in the two methods of correction data for the non-additives effects. The non-additive effects were not similar in magnitude and direction in the two estimation methods used, nor for the characteristics evaluated. Pearson and Spearman correlations between breeding values were higher than 0.94, and the use of different methods does not imply changes in the selection of animals.

Scrotal Circumference at Puberty and its Relationship to Testes Mass in Three Genotypes of Beef Cattle

Scrotal circumference (SC) is a simple, non-invasive measurement commonly used to evaluate bull breeding potential although its validity as a predictor of fertility is questionable (Holroyd, 1998). SC is highly heritable but varies with breed and animal factors such as condition, live weight and age. As an indicator of fertility, recommended SC values range broadly from 30cm to 38cm (Miller, 1992). It is assumed that SC accurately reflects testes mass (TM) which may be related to direct measures of fertility such as spermatogenesis (Entwistle, 1992). The SC measurements made here test the assumption that SC, used to estimate testes volume (TV), is directly related to TM. Miller (1992) reported a value of 261mm as the SC threshold for puberty. We have studied serial SC measurements so as to devise a more accurate means of using SC to determine puberty.

The Performance of Chromium and Ytterbium Intraruminal Controlled Release Devices in Beef Cattle

The estimation of feed efficiency in beef cattle should be undertaken in the environment where the genetic potential of the animal is to be expressed. Consequently if cattle are to be pasture fed, there is a requirement for accurate feed intake measurements on individual animals in the field. This in turn requires the use of accurate faecal marker delivery systems.

Developing a Beef Cattle Nutritional Management Education Package for Producers in Northern Australia

Meat and Livestock Australia (MLA) and the Queensland Beef Industry Institute (QBII) used the marketing process Quality Function Deployment (QFD) to determine the education needs of beef producers in northern Australia with regards to beef cattle nutrition management. This is the first time that such a process has been conducted in this sector of the industry. 290 producers from across Queensland, the Northern Territory and Western Australia were interviewed. The results of this process provide considerable insights into issues of concern to northern producers in terms of beef cattle nutrition and how education, extension and research organisations can ensure that they meet the needs of their target audience. Animal production for a consuming world : proceedings of 9th Congress of the Asian-Australasian Association of Animal Production Societies [AAAP] and 23rd Biennial Conference of the Australian Society of Animal Production [ASAP] and 17th Annual Symposium of the University of Sydney, Dairy Research Foundation, [DRF]. 2-7 July 2000, Sydney, Australia.

The Effect of Post-Pubertal Castration on Behaviour in Beef Cattle

Castration of male beef cattle is advantageous for management, however pre-pubertal (early) castration results in comparative losses in growth rate (Jago et al., 1996). Post-pubertal (late) castration may maintain growth rate but lead to management problems. The behavioural differences between early castrates (9mo) and late castrates (18mo), which may have an effect on growth rate were studied.

Clinical and pathological findings associated with congenital hypovitaminosis A in extensively grazed beef cattle

To determine the cause of exceptionally high mortality (41.4%) in perinatal calves on a beef cattle property 50 km south-west of Julia Creek in north-western Queensland. Investigations were based on clinical assessment of affected calves and laboratory analysis of pre- and postmortem specimens taken from 12 calves aged from 6 to 36 h of age. Associations between gross and histopathological findings and biochemical analyses conducted on serum and tissue samples were examined in relation to clinical observations. Clinical signs varied, but commonly included mild to severe ataxia, difficulty finding a teat and sucking, blindness (partial or complete, as judged by avoidance of obstacles) and depression with prominent drooping of the head. Gross and histopathological findings included herniation of the cerebellar vermis through the foramen magnum, squamous metaplasia of interlobular ducts in the parotid salivary glands and Wallerian degeneration of the optic nerves. Biochemical analysis of serum and liver samples available from four of the calves revealed low or undetectable levels of both vitamin A and vitamin E. Although vitamin E is known to have a sparing effect on vitamin A, the role (if any) played by deficiency of this vitamin was uncertain. The combination of clinical signs, postmortem findings, histopathological features and biochemical findings indicate that gestational vitamin A deficiency was highly likely to have been an important contributor to perinatal calf mortalities in this herd.

Quality of handling and holding yard environment, and beef cattle temperament: 1. Relationships with flight speed and fear of humans.

Numerous tests have been used to measure beef cattle temperament, but limited research has addressed the relationship between such tests and whether temperament can be modified. One-hundred-and-forty-four steers were given one of three human handling and yarding experiences on six occasions during a 12-month grazing period post-weaning (backgrounding): Good handling/yarding, Poor handling/yarding and Minimal handling/yarding. At the end of this phase the cattle were lot-fed for 78 days, with no handling/yarding treatments imposed, before being transported for commercial slaughter. Temperament was assessed at the start of the experiment, during backgrounding and lot-feeding by flight speed (FS) and a fear of humans test, which measured the proximity to a stimulus person (zone average; ZA), the closest approach to the person (CA) and the amount the cattle moved around the test arena (total transitions; TT). During backgrounding, FS decreased for all treatments and at the end of backgrounding there was no difference between them. The rate of decline, however, was greatest in the Good group, smallest in the Minimal group with the Poor intermediate. In contrast, ZA was affected by treatment, with a greater reduction for the Good group than the others (P = 0.012). During lot-feeding, treatment did not affect FS, but all groups showed a decrease in ZA, with the greatest change in the Poor group, the least in the Good and the Minimal intermediate (P = 0.052). CA was positively correlated with ZA (r = 0.18 to 0.66) and negatively with TT (r = -0.180 to -0.659). FS was consistently correlated with TT only (r = 0.17 to 0.49). These findings suggest that FS and TT measure a similar characteristic, as do ZA and CA, but that these characteristics are different from one another, indicating that temperament is not a unitary trait, but has different facets. FS and TT measure one facet that we suggest is general agitation, whilst ZA and CA measure fear of people. Thus, the cattle became less agitated during backgrounding, but the effect was not permanently influenced by the quantity and quality of handling/yarding. However, Good handling/yarding reduced fearfulness of people. Fear of people was also reduced during lot-feeding, probably as a consequence of frequent exposure to humans in a situation that was neutral or positive for the cattle.

A review of factors that impact on the capacity of beef cattle females to conceive, maintain a pregnancy and wean a calf - implications for reproductive efficiency in northern Australia.

A review of factors that may impact on the capacity of beef cattle females, grazing semi-extensive to extensive pastures in northern Australia, to conceive, maintain a pregnancy and wean a calf was conducted. Pregnancy and weaning rates have generally been used to measure the reproductive performance of herds. However, this review recognises that reproductive efficiency and the general measures associated with it more effectively describe the economic performance of beef cattle enterprises. More specifically, reproductive efficiency is influenced by (1) pregnancy rate which is influenced by (i) age at puberty; (ii) duration of post-partum anoestrus; (iii) fertilisation failure and (iv) embryo survival; while (2) weight by number of calves per breeding female retained for mating is influenced by (i) cow survival; (ii) foetal survival; and (iii) calf survival; and (3) overall lifetime calf weight weaned per mating. These measures of reproductive efficiency are discussed in depth. Further, a range of infectious and non-infectious factors, namely, environmental, physiological, breed and genetic factors and their impact on these stages of the reproductive cycle are investigated and implications for the northern Australian beef industry are discussed. Finally, conclusions and recommendations to minimise reproductive inefficiencies based on current knowledge are presented.

Optimising growth paths of beef cattle in northern Australia for increased profit

Strategies for increasing growth of cattle using different growth paths.

Persistence of orally administered Megasphaera elsdenii and Ruminococcus bromii in the rumen of beef cattle fed a high grain (barley) diet

When cattle are fed grain, acidotic ruminal conditions and decreased efficiency in starch utilisation can result from the rapid production and accumulation of lactic acid in the rumen. The efficacy of drenching cattle with Megasphaera elsdenii and Ruminococcus bromii to improve animal performance was investigated. A feedlot trial was undertaken with 80 Bos indicus crossbred steers (initial liveweight 347.1 (s.d. 31.7) kg) in 10 pens in a randomised complete block design. An empty-pen-buffer was maintained between treated (inoculated) and untreated (control) groups to avoid transfer of inoculant bacteria to the control steers. Inoculated steers were orally drenched with M. elsdenii YE34 and R. bromii YE282, and populations increased rapidly over 3-14 days. The steers were fed for a total of 70 days with commercial, barley-based, feedlot rations. High growth rates (1.91 kg per day) were achieved throughout the experiment in both the inoculated and control steers. Intakes averaged 21.3 g dry matter (DM) per kg liveweight per day. There was probably no acidosis achieved in this trial following challenge (i.e. no change in pH occurred). There were no differences in any production or carcass measurements between the control and inoculated steers overall. However, the control group acquired dense ruminal populations of M. elsdenii by Day 14, while R. bromii populations established at high densities within the first 2 weeks but then declined and were undetectable by Day 50. R. bromii appears to be only transiently dominant, and once its dominance waned, it appeared that Ruminobacter spp. established in the rumen. Ruminobacter spp. became dominant between 14 and 28 days in all the steers examined and persisted through to the end of the study. These Ruminobacter spp. may be of future interest in the development of probiotics for grain-fed cattle.

Wild dog control impacts on calf wastage in extensive beef cattle enterprises

Wild dogs (Canis lupus dingo and hybrids) are routinely controlled to protect beef cattle from predation yet beef producers are sometimes ambivalent as to whether wild dogs are a significant problem or not. This paper reports the loss of calves between birth and weaning in pregnancy-tested herds located on two beef cattle properties in south-central and far north Queensland for up to 4 consecutive years. Comparisons of lactation failures (identified when dams that previously tested pregnant were found non-lactating at weaning) were made between adjoining test herds grazed in places with or without annual (or twice annual) wild dog poison baiting programs. No correlation between wild dog relative abundance and lactation failures was apparent. Calf loss was frequently higher (three in 7 site-years, 11–32%) in baited areas than in non-baited areas (9% in 1 of 7 site-years). Predation loss of calves (in either area) only occurred in seasons of below-average rainfall, but was not related to herd nutrition. These data suggest that controlling wild dogs to protect calves on extensive beef cattle enterprises is unnecessary in most years because wild dogs do not routinely prey on calves. In those seasons when wild dog predation might occur, baiting can be counter-productive. Baiting appears to produce perturbations that change the way surviving or re-colonising wild dog populations select and handle prey and/or how they interact with livestock.