Large Commercial Herds Research Articles

39 Using genetics and technology to improve swine robustness

Abstract Abstract Pig robustness has been an increasing concern in the global swine industry over the last 10 yr. This trend of increased mortality across all phases of production continues to worsen over time despite greater focus on research, management, and other production practices to control it. During this time, dramatic improvements in genetic progress have been realized through the selection of economically important traits. Historically, swine genetic companies have relied on data from their purebred animals reared in high-health and well-managed environments which has proven difficult to provide meaningful insight on variation in robustness traits. More recently, leading genetic companies have invested in large commercial test herds where crossbred pigs and breeding animals are individually identified with pedigree and genomic information. These pigs are reared under challenging and varying commercial conditions and mortality, removals, and reproductive efficiency data are gathered and used to generate crossbred breeding values. This type of data increases the accuracy of genetic estimates as well as creates new traits aimed at improving robustness and ease of management. Further investments have been made in precision livestock farming technologies such as computer vision which is quickly being developed due to the low cost of cameras and the ability to use edge computing to process images in real-time or to transfer images and data to the cloud. These developments are particularly compelling in the genetic improvement space when they can be paired with individual animal identification enabling novel traits to be measured in large populations more consistently and at a reduced cost compared with previous labor-intensive or cost-prohibitive methods. Early examples of this are the use of cameras to score feet and leg soundness in replacement gilts as lameness and associated feet and leg injuries are still one of the largest contributors to sow culls and mortality. This new digital feet and leg soundness scoring method has initially resulted in dramatically greater accuracy and heritability compared with conventional subjective human scoring methods. Other camera-based algorithms have been developed to track individual pigs and assess their daily behaviors and interactions. These developments are key to collecting new phenotypes for the selection of positive behavior traits for genetic selection compared with what was previously possible with human observer or scan sampling methods. Gene editing is another promising technology that has been used in human health and plant breeding but is now being widely researched in livestock. This technology has been used to create the first PRRS-resistant pigs to address one of the most costly diseases in the industry. New sources of data and technologies are key to creating and capturing existing and novel phenotypes on large populations of pigs in commercial environments to aid in the genetic improvement of non-conventional traits.

The association of immune response and colostral immunoglobulin G in Canadian and US Holstein-Friesian dairy cows

In cattle, maternal immunoglobulins are transferred through colostrum to provide passive immunity to the neonatal calf once they are absorbed into circulation. Cows can be assessed for antibody- and cell-mediated immune responses (AMIR and CMIR, respectively), and through estimated breeding values (EBV) and genomic parent averages (GPA), cows can be classified as having high, average, or low immune response (IR). The objective of this study was to identify associations of colostral IgG concentrations with IR in dairy cows. High IR dairy cows identified by GPA or EBV were hypothesized to produce higher colostral IgG concentrations than cows with average or low IR. Colostrum was collected from Holstein dairy cows from 3 large commercial herds (n = 590) in the United States and 1 research herd at the Ontario Dairy Research Centre (n = 275) in Canada. For the US herds, IR GPA were available through genotyping. For the Canadian herd, IR EBV were available through phenotyping and pedigree information. Colostral IgG concentrations were measured by radial immunodiffusion and analyzed using general linear models in SAS. Based on a prediction equation, cows in US herds with a CMIR GPA of 1 would have colostral IgG concentrations 6.3 g/L higher on average than cows with a CMIR GPA of 0. High CMIR cows produced statistically greater colostral IgG concentrations (least squares mean ± standard error of the mean, 107.5 ± 7.7 g/L) than low CMIR cows (91.4 ± 7.1 g/L), with intermediate values for average CMIR cows (105.1 ± 5.6 g/L). No differences were found among AMIR categories in US cows. The Canadian herd showed a trend for cows with high CMIR EBV (continuous variable) to produce greater colostral IgG. No differences were observed among high, average, and low AMIR EBV classifications in Canadian cows. The findings suggest that selective breeding of Holstein cows to enhance CMIR could contribute to higher-quality colostrum in succeeding generations.

Chemical and granulometric characterization of soil and its influence on the bromatologic composition of pastures in savannah region, Central Brazil

Livestock is responsible for much of the world's land use, and grazing areas are the main livelihood of the world's largest commercial herd. Most of the pasture areas have low productivity because they are at some level of degradation. This study aimed to apply multivariate analysis and remote sensing techniques for to evaluate the influence of soil granulometric chemical characteristics and bromatologic composition associated with vegetative index classes of pastures cultivated in the Savana biome, region of Central Brazil. The pasture areas were selected according to Normalized Difference Vegetation Index (NDVI) considering the annual average and their classification into a low vegetative index (LVI), medium vegetative index (MVI), and high vegetative index (HVI) levels. Forage material collections were carried out on six dates (bimonthly) and a soil collection date. Productive parameters of the pasture were evaluated: fresh mass (FM), dry mass (DM) and tillers (TILL); pasture bromatologicals: crude protein (CP), total dry matter (TDM), dry matter, ether extract (EE), neutral detergent fiber (NDF) and acid detergent fiber (ADF), and non-woven fabric (NW); the chemical composition of the soil: pH, Ca, Mg, Al, total acidity, P, K, cation exchange capacity (CEC), organic matter (OM), base saturation; and soil granulometric: clay, silt, and sand contents. The results were submitted to descriptive statistical analysis and discriminant analysis by partial least squares (PLS-DA). The PLS-DA analysis method allowed us to differentiate pasture areas in terms of vegetative indices (HVI and LVI) through the chemical and granulometric parameters of the soil and by the productive and bromatological parameters of the pastures. The granulometric characteristics of the soils were the parameters with the lowest weight to differentiate the pastures in terms of low, medium, and high vegetative indexes. Pastures with high vegetative index (HVI), even in intensive systems, showed better chemical quality (Mg, P, K, OM, CEC, and Ca) of soils and bromatological quality of forages (FM, ADF, PB, and TDM).

Genomic Analysis of Purebred and Crossbred Angus Cows Quantifies Heterozygosity, Breed, and Additive Effects on Components of Reproduction.

Simple SummaryThis study reports a genomic analysis of purebred Angus and Hereford × Angus maternal productivity, which is a key driver of sustainable systems. Heterozygosity effects quantify hybrid vigour or heterosis and were significant for growth and puberty. Breed differences were mostly due to heterosis, but there was an advantage of Hereford genes for reproductive performance. Days to calving was the most important Estimated Breeding Value (EBV) as a predictor of attainment of puberty and subsequent reproductive performance. Genomics offers a cheaper and faster strategy for the development of multi-breed EBVs in commercial herds.Multiple studies have quantified the production differences of Hereford Angus crossbreds compared to purebred Angus for a range of traits including growth, carcass, and reproductive traits. This study aims to quantify breed and heterosis effects on maternal performance using genomics. Thirty Hereford and thirty Angus sires were mated to 1100 Angus heifers and cows in a large commercial herd run on pasture at Musselroe Bay, Tasmania, Australia. Approximately 1650 calves were born. Heifers were weaned, scanned for attainment of puberty prior to joining at approximately 15 months of age, joined, and then recorded for status of pregnancy, calving, lactating, 2nd pregnancy, and weaning of second calf. Heterozygosity effects were significant for heifer pre-joining weight and height as well as proportion pubertal. Breed differences were significant for the same traits plus pregnancy rate at second joining and proportion rearing two calves. Genetic parameters were reported for 13 traits. On average, higher genetic merit (Estimated Breeding Value, EBV percentile) Hereford bulls were used than Angus for growth and puberty, but they were similar for fat and reproduction. Days to calving BREEDPLAN EBVs of the sires were related to puberty and reproduction. Scrotal size BREEDPLAN EBVs of the sires were related to attainment of puberty genomic EBVs calculated. In summary, breed differences in growth and puberty were due to heterosis, but there was an advantage of Hereford genes for reproductive performance. Ongoing emphasis on selection for reduced days to calving and estimation of multi-breed EBVs is important.

Milk Production and Reproductive Performance of Retained and Culled Cows in a Large Holstein Herd in Egypt

The study aimed to identify the culling reasons of Holstein cows raised in a large commercial herd in Egypt with emphasis on the performance of retained and culled cows. A total of 31534 complete lactation records for 10994 cows calved from 2008 to 2019 were used. The overall rate of culling per lactation was 61.1%. Involuntary culling represented 92% of all culling cases. The reasons for culling included mastitis and udder problems (24.2%), reproductive disorders (18.7%), metabolic and digestive disorders (13.6%), lameness (13%), endemic diseases (10.8%), low milk yield (8.1%), respiratory diseases (4.3%) and unknown causes (7.3%). Means of 305-day milk yield and daily milk yield were significantly lower in culled cows than the retained ones. On the other hand, no significant differences were observed between culled and retained cows for days open and the number of services/conception. The high involuntary culling rate of Holstein under the Egyptian conditions revealed that management practices regarding mastitis prevention and reproductive efficiency should be improved.

The use of Hereford sires over mature Angus dams can add value to Angus cattle herds

Context Overseas studies have quantified production differences of Hereford × Angus compared with purebred Angus for a range of traits including growth, carcass and reproductive traits. Aim This study aims to provide a comparison of Hereford × Angus and purebred Angus under modern grazing conditions in southern Australia. Methods Thirty Hereford and 22 Angus sires were mated to 1100 Angus cows and heifers in a large commercial herd run on pasture at Musselroe Bay, Tasmania. Approximately 1650 calves were born. Steers were grown on pasture for an average of 23 months and then slaughtered. Results Hereford sired calves were heavier at birth (+8.8%) and weaning (+4.1%). Hereford-sired calves from heifers (but not from mature cows) had more assisted births (+8.2%) and more calf deaths (10.0% vs 5.1%). Hereford-sired steers had higher hot standard carcass weight (+4.1%) and eye-muscle area (+3.2%) but when hot standard carcass weight was fitted as a covariate, eye-muscle area was no longer significant. Carcass quality measures (AUSMEAT marbling –25.8%, Meat Standards Australia marbling –10.5%, Meat Standards Australia index –1.0%) were poorer for Hereford-sired steers and fat colour (+6.9%) was darker. Meat samples from Hereford-sired steers had significantly lower colour indicators (L and b). There was no difference in cooking loss and shear force, and intramuscular fat was lower (3.0% vs 4.1%). Conclusions Hereford × Angus calves were heavier at birth than were purebred Angus, but had more calving difficulty and deaths associated with heifer dams. Hereford × Angus carcasses were heavier but had lower indicators of quality than did purebred Angus. Implications As Hereford × Angus steers produced a 4.1% heavier carcass, pure Angus steers would need to attract a premium of at least 4.1% for the additional marbling to give more value. Hereford bulls could be mated to Angus cows and not Angus heifers to avoid calving difficulties. Alternatively, good calving Hereford bulls could be selected using estimated breeding values when mating to Angus heifers.

Genomic analysis of purebred and crossbred Angus cattle demonstrates opportunity for multi-breed evaluation

Context Overseas studies have quantified production differences of Hereford Angus crossbreds compared with purebred Angus for a range of traits including growth, carcass and reproductive traits. Aim This study aimed to quantify breed and heterosis effects using genomics. Methods Thirty Hereford and 30 Angus sires were mated to 1100 Angus cows and heifers in a large commercial herd run on pasture at Musselroe Bay, Tasmania. Approximately 1650 calves were born. Steers (743) were grown for an average of 23 months and then slaughtered. Results Heterozygosity effects were significant for birth, weaning and carcass weight and also loin eye-muscle area. On average, higher-quality (percentile) Hereford than Angus bulls were used. Breeding values were calculated for sires and could be compared with a common base given they also had BREEDPLAN breeding values published. Conclusions When heterozygosity was accounted for and when compared on a common base, progeny of average Angus sires were superior to progeny of Hereford sires for birthweight, carcass weight, eye-muscle area and intramuscular fat. Implications The method of benchmarking breeds using crossbred cattle and genomics provides a model for rapid adoption of multi-breed estimated breeding values, which is desirable for commercial beef producers.

An Assessment of Secondary Clinical Disease, Milk Production and Quality, and the Impact on Reproduction in Holstein Heifers and Cows from a Single Large Commercial Herd Persistently Infected with Bovine Viral Diarrhea Virus Type 2.

The aim of this study was to evaluate secondary clinical disease, milk production efficiency and reproductive performance of heifers and cows persistently infected (PI) with bovine viral diarrhea virus type 2 (BVDV type 2). PI animals (n = 25) were identified using an antigen capture ELISA of ear notch samples. They were distributed into three age groups: ≤ 12 (n = 8), 13 to 24 (n = 6) and 25 to 34 (n = 11) months old. A control group of BVDV antigen ELISA negative female cattle that were age matched to the PI animals was utilized from the same herd. The PI group had a 1.29 higher odds ratio for diarrhea than controls (p = 0.001, IC95% = 1.032–1.623) and 1.615 greater chance of developing bovine respiratory disease (BRD) (p = 0.012, IC95% = 1.155–2.259). The age at first insemination (p = 0.012) and number of insemination attempts required to establish the first pregnancy (p = 0.016) were both higher for PI than controls. Milk production was higher for control cows than PI cows during most of the sampling periods. Somatic cell counts (SCC) were higher in PI cows than the controls at all sampling points across lactation (p ≤ 0.042). PI cattle had a higher incidence of disease, produced less milk, a higher SCC, and poorer reproductive performance than control cattle in this study.

Trajetórias da bovinocultura de corte na Argentina e no Brasil: uma análise histórica e comparada sobre os efeitos das políticas de estado nos últimos dois séculos

Nos últimos 200 anos, Argentina e Brasil dividiram a importância na produção e na comercialização global decarne bovina. Num primeiro momento, ao longo de quase um século, a detenção de tal poder esteve na mão dos portenhos, que utilizaram muito bem as características das terras pampeanas para multiplicar os seus rebanhos.Nos últimos 60 anos, porém, de forma surpreendente, o Brasil assumiu essa tarefa e se tornou o detentor domaior rebanho comercial do mundo e o maior exportador de carne bovina do planeta. Nesse estudo, por meio de uma análise histórico-comparativa, buscou-se analisar qual a participação do Estado no crescimento do rebanho bovino, em cada um dos dois países, ao longo desse período. Para tanto, segmentou-se o tempo em subperíodos, os quais foram denominados de ‘casos’ e criou-se parâmetros de comparação através de uma gradação indicativa do impacto provocado pelas políticas e ações governamentais sobre o crescimento dos rebanhos. Utilizou-se fontes secundárias e documentais para levantar os dados históricos. Os resultadosmostraram que, tanto na Argentina, quanto no Brasil, a participação estatal, direta ou indireta, foi determinante para influenciar no crescimento dos rebanhos e na consequente participação do agronegócio da carne bovina na balança comercial dos dois países.

Genetic parameters for fertility traits in Nellore bulls.

Nellore is the main cattle breed used in Brazil, being the largest commercial herd in the world. Beyond the importance of male reproductive efficiency for farm profit, the use of reproductive techniques, mainly artificial insemination, turns the evaluation of male reproductive traits even more important. Estimation of genetic parameters increases the knowledge on traits variances and allows envisaging the possibility of the inclusion of new traits as selection criterion. Genetic parameters for fifteen traits that can be classified as testicular biometry or physical and morphological semen traits were estimated for a Nellore bull population ranging from 18 to 36months. Single-trait and bi-trait animal models were used for (co)variance components estimation. The contemporary group was considered as fixed effect and age at measurement as covariable. Scrotal circumference presented heritability of 0.47±0.12. This value is similar to the heritabilities found for all testicular biometry traits (0.34-0.48). Sperm progressive motility, which has a direct effect on bull fertility, presented low heritability (0.07±0.08). Major and total sperm defects presented moderate to high heritabilities (0.49±0.18 and 0.39±0.15, respectively), indicating that great genetic gain can be obtained through selection against sperm defects. High and positive genetic correlations were observed among testicular biometry traits, which also presented favourable genetic correlations with physical and morphological traits of the semen with magnitude ranging from high to low. Scrotal circumference presented moderate to high and favourable genetic correlations with sperm progressive motility, sperm turbulence, major sperm defects and total sperm defects. Thus, the selection for scrotal circumference results in favourable correlated genetic response for semen quality. The results show that the use of scrotal circumference as reference trait for bull fertility is appropriate, since it presents high heritability and favourable genetic correlation with semen quality.

Effect of growth hormone on milk yield and reproductive performance of subfertile Holstein cows during extended lactations

The objective of this study was to determine the effects of the administration of recombinant bovine somatotropin (rbST) throughout lactation to high-yielding subfertile (conception > 270 days postpartum) Holstein cows undergoing extended lactations (≥480 d) on milk production and reproductive performance. The study used two large adjacent commercial herds with similar management in a hot area of northern Mexico (25° N). Cows in one herd (n=2341) received a 500-mg dose of rbST every 14 d until dried off, starting 60 days postpartum. The other herd served as control (n=984). Across parity, rbST-treated cows produced 20% greater milk yield than control cows in 305-d lactations. Across parities, milk yield from 305 d postpartum to the end of lactation was 2734 kg higher in rbST-treated cows than control cows. Across parities rbST-treated cows produced 4777 more kg of milk during the entire lactation (mean 605 d) than the control group (mean 572 d). Conception rates (CR) at first service were only 3.2% and 5.9% (p<0.05) for control and rbST-treated cows, respectively. Overall CR was 43.5% and 61.6% (p<0.05) for control and treated cows, respectively. Control cows required 2.4 more (p<0.01) services per conception than rbST-treated cows. It was concluded that in this hot environment, the use of rbST suits dairy producers because it substantially improves both milk yield and reproductive performance in subfertile high-yielding Holstein cows. By markedly increasing lactation length and lactation persistency farm efficiency is greatly improved due to extended herd life.

Prevalence of methicillin-resistant Staphylococcus aureus among large commercial pig herds in South Africa.

The prevalence of nasal carrier status of methicillin-resistant Staphylococcus aureus (MRSA) in pigs has been described elsewhere, but is unknown in South Africa. To address concerns that exist regarding the zoonotic risk that carriers pose to workers, the herd-level prevalence of MRSA was determined among 25 large (> 500 sows) commercial pig herds in South Africa, representing 45% of the large commercial herds in the country. From each herd, the nasal contents of 18 finisher pigs were sampled at the abattoir, pooled into three and selectively cultured to determine the presence of MRSA. A herd was classified as MRSA-positive if one or more of the three pooled samples cultured positive. Three of the 25 herds tested positive for MRSA, equating to a 12% herd prevalence (95% CI: 7% – 23%) among South African commercial piggeries. The prevalence of nasal MRSA carriers among large commercial pig herds in South Africa was low compared to what has been reported elsewhere and suggests a relatively low zoonotic MRSA risk to workers in South African commercial piggeries and abattoirs.

Assessing the Spatial and Occupation Dynamics of the Brazilian Pasturelands Based on the Automated Classification of MODIS Images from 2000 to 2016

The pasturelands areas of Brazil constitute an important asset for the country, as the main food source for the world’s largest commercial herd, representing the largest stock of open land in the country, occupying ~21% of the national territory. Understanding the spatio-temporal dynamics of these areas is of fundamental importance for the goal of promoting improved territorial governance, emission mitigation and productivity gains. To this effect, this study mapped, through objective criteria and automatic classification methods (Random Forest) applied to MODIS (Moderate Resolution Imaging Spectroradiometer) images, the totality of the Brazilian pastures between 2000 and 2016. Based on 90 spectro-temporal metrics derived from the Red, NIR and SWIR1 bands and distinct vegetation indices, distributed between dry and wet seasons, a total of 17 pasture maps with an approximate overall accuracy of 80% were produced with cloud-computing (Google Earth Engine). During this period, the pasture area varied from ~152 (2000) to ~179 (2016) million hectares. This expansion pattern was consistent with the bovine herd variation and mostly occurred in the Amazon, which increased its total pasture area by ~15 million hectares between 2000 and 2005, while the Cerrado, Caatinga and Pantanal biomes showed an increase of ~8 million hectares in this same period. The Atlantic Forest was the only biome in which there was a retraction of pasture areas throughout this series. In general, the results of this study suggest the existence of two relevant moments for the Brazilian pasture land uses. The first, strongly supported by the opening of new grazing areas, prevailed between 2000 and 2005 and mostly occurred in the Deforestation Arc and in the Matopiba regions. From 2006 on, the total pasture area in Brazil showed a trend towards stabilization, indicating a slight intensification of livestock activity in recent years.

Nutritional aspects related to the interval between calves

It is known that the demand for products of bovine origin increases every day in the world, and Brazil, which has the largest commercial herd of cattle on the planet, does not stay behind when it comes to raising beef cattle and milk. Despite our efforts to offer the best product, we are faced with difficult challenges in the country when it comes to climate and soil. The tropical climate, with rainy and dry seasons, ends up greatly damaging the pastures, thus offering less quality nutrients to our herds. As a domino effect, with less nutrients, there is more stress on the animal, which implies a poor reproductive efficiency, which is a crucial factor for effective production. However, there are viable outputs to improve the statistics, and one of them is reducing the interval between calving in cows relating to nutritional aspects, the important theme that the work will address. The nutritional strategy used in the experiment was the supplementation before, during and after the synchronization protocols for IATF. It consisted in the supply of 5g / kg PV / animal / day, a multiple mixture containing 82% ground corn, 8% soybean meal, 4% protected fat (Megalac®), 3% protected urea , 2% calcium carbonate, 0.06% mineral core, 0.04% Sodium Chloride and 0.01% lasalocid sodium 15% (Taurotec®). Supplement delivery started 7 days prior to protocol (D0) and lasted up to 20 after TAI, totaling 38 days. It was observed that the results showed an increase in the pregnancy rate of the primiparas that were supplemented, especially those with ECC below 3 (on the scale of 1 to 5), the percentage variation in the increment was of 2.6 ( ECC ≥3) to 7.1 (ECC = 2.75), presenting lower values in multiparous women. It is evident that, with due planning, observing the moments of nutritional deficit, it is possible to improve the interval between deliveries, thus improving production.

Lactation performance of Holstein cows treated with 2 formulations of recombinant bovine somatotropin in a large commercial dairy herd in Brazil

The objectives of this controlled study were to compare the effects of 2 different formulations of recombinant bovine somatotropin (rbST) on milk yield, milk composition (fat and protein), milk somatic cell count, and body condition score (BCS) among dairy cattle in a large commercial herd. Regulatory approved 500-mg zinc sesame oil base rbST (ZSO-rbST; Elanco Animal Health, Greenfield, IN) and vitamin E lecithin base rbST (VEL-rbST; LG Life Sciences, Seoul, South Korea) formulations were administered per the manufacturers' recommendations every 14 d over 17 injection cycles starting at 57 to 70 d of lactation (90 cows per rbST group). Control cows (n = 60) received no rbST. Somatotropin-treated animals (VEL-rbST and ZSO-rbST combined) had increased average milk yield and protein percentage and lower average BCS compared with control cows. For primiparous cows, average milk yield was 37.75 kg/d with the ZSO-rbST treatment and 35.72 kg/d with the VEL-rbST treatment. For multiparous cows, average milk yield was 40.13 kg/d with the ZSO-rbST treatment and 38.81 kg/d with the VEL-rbST treatment. There were no differences in milk fat percentage between VEL-rbST and ZSO-rbST treatments, but milk protein content was greater with VEL-rbST treatment than with ZSO-rbST treatment. Nonetheless, cows treated with ZSO-rbST yielded more kilograms of fat and protein per day than cows treated with VEL-rbST. No significant differences in BCS were found between both rbST treatment groups. The differential increase in milk yield between cows treated with ZSO-rbST and VEL-rbST was driven by rbST response differences both within the 14-d cycle and throughout the 17 injection cycles. The cows treated with VEL-rbST demonstrated a more variable 14-d milk yield response curve, with more pronounced valleys between injections compared with the ZSO-rbST formulation. In addition, only the ZSO-rbST treatment was effective in modifying the lactation persistency compared with control cows. Compared with the VEL-rbST formulation, the ZSO-rbST formulation yielded more kilograms of milk, fat, and protein with less milk variation throughout the seventeen 14-d lactation cycles for both primiparous and multiparous cows.

Genomic analyses of tropical beef cattle fertility based on genotyping pools of Brahman cows with unknown pedigree.

We introduce an innovative approach to lowering the overall cost of obtaining genomic EBV (GEBV) and encourage their use in commercial extensive herds of Brahman beef cattle. In our approach, the DNA genotyping of cow herds from 2 independent properties was performed using a high-density bovine SNP chip on DNA from pooled blood samples, grouped according to the result of a pregnancy test following their first and second joining opportunities. For the DNA pooling strategy, 15 to 28 blood samples from the same phenotype and contemporary group were allocated to pools. Across the 2 properties, a total of 183 pools were created representing 4,164 cows. In addition, blood samples from 309 bulls from the same properties were also taken. After genotyping and quality control, 74,584 remaining SNP were used for analyses. Pools and individual DNA samples were related by means of a "hybrid" genomic relationship matrix. The pooled genotyping analysis of 2 large and independent commercial populations of tropical beef cattle was able to recover significant and plausible associations between SNP and pregnancy test outcome. We discuss 24 SNP with significant association ( < 1.0 × 10) and mapped within 40 kb of an annotated gene. We have established a method to estimate the GEBV in young herd bulls for a trait that is currently unable to be predicted at all. In summary, our novel approach allowed us to conduct genomic analyses of fertility in 2 large commercial Brahman herds managed under extensive pastoral conditions.

Suplementação de fêmeas bovinas em pastejo: aspectos nutricionais e reprodutivos

Brazil has a cattle production chain based on grazing production, which makes it inexpensive, but with a low profit margin. For that reason, it has gone through a series of changes due to competition with other animal protein production chains, such as pigs and poultry and also with the agriculture, which rapidly moves into areas that were previously occupied for the livestock farming. Thus, with a scenario of low profitability and high competition, it is necessary to find alternatives that allow its survival and profitability. Even with the largest commercial herd in the world, Brazilian livestock presents levels below its true potential, especially due to the low reproductive efficiency of the females of the herd. So that the activity becomes sustainable, it is important the inclusion of technologies to make use of the maximum productive capacity of these animals. Recently, many studies have been done regarding the supplementation of grazing females, and it presents itself as an essential alternative in both the birth or rearing processes, in view of the fact that the adequate intake of nutrients is essential for reproductive development in cattle. The Zebu extensive management system, which is used in most of the cattle farms in Brazil, is the main cause of the delayed puberty of these animals, which will interfere in the age they went into the breeding season and the age of the first calving. Also during pregnancy the proper nutritional support is extremely important, evidence shows that the development of the skeletal muscle and deposition of adipose tissue of the fetus may be altered in cases of malnutrition, with long-term effects on their performance in adulthood. This study aimed at pointing out some aspects that confirm the influence of nutrition on reproductive physiology of grazing females receiving supplementation.

The value of improved pastures to Brazilian beef production

Brazil is an agricultural country, with 190 Mha of pastures sustaining 209 million cattle. Fewer than 10% of the cattle are fattened in feedlots, whereas cattle reared on pastures have a competitive advantage for export, eliminating the risks presented by the mad cow disease (bovine spongiform encephalopathy) and considerations related to animal welfare. Brazil has been the world’s largest exporter of beef since 2004 and has the largest commercial herd in the world. In 2011, 16.5% of its production was exported, and the livestock sector contributed 30.4% of the gross national product from agribusiness and 6.73% of the total GNP. Many forage breeding programs, mainly at Embrapa, have contributed to the development of improved pastures, and cultivars of Brachiaria brizantha, B. decumbens, B. humidicola and Panicum maximum are the main pastures used in the country. All have apomictic reproduction, which means there are few cultivars occupying very large, continuous areas, thus suggesting a risk to the productive system. Such is the case of B. brizantha cv. Marandu, which occupies around 50 Mha. The Brazilian tropical forage seed industry is also important, and Brazil is the main seed exporter, supplying all Latin American countries. Due to pasture degradation, around 8 Mha is renovated or recovered each year. Forages are also used and planted each year in integrated crop–livestock and integrated crop–livestock–forest systems. Nowadays, these systems occupy 4 Mha. Improved pastures are thus a major asset in Brazil not only for the beef production chain but also for the dairy industry.

A study based on records taken at time of hoof trimming reveals a strong association between the IQ motif-containing GTPase-activating protein 1 (IQGAP1) gene and sole hemorrhage in Holstein cattle

Feet and leg problems have a major effect on the well-being and lifespan of the dairy cow and thus are economically important to the dairy farmer. Apart from approaches using genetic selection for classical traits from conformation scoring, attempts for genetic improvement can be based either on records of individual disease cases or on records of disorder status at time of hoof trimming. In this study, 1,962 first-lactation cows were subjected to hoof trimming with an assessment of disorder status for sole hemorrhage as a binary trait. Cows were from 7 large commercial herds in Mecklenburg-Western Pomerania (northeastern Germany) that had similar housing with cubicles, slatted flooring, little use of straw for bedding, and total mixed ration feeding. Cows were trimmed and assessed once, focusing on cows in the first half of the lactation. Herds were visited at intervals to enable recording of cohorts at a similar stage of lactation. Each cohort or herd-visit included between 31 and 165 cows. Additional measurements included body weight, back fat thickness, and body condition at time of trimming. Further data on dairy production, conformation scores, and reproductive performance were merged after collection of records had finished. The DNA extracted from blood of 1,183 cows was used for analysis with a custom-made array of 384 single nucleotide polymorphisms (SNP). The SNP were selected according to results from the literature for effects in classical conformation traits, from biochemical pathway analysis, and from comparative analysis of putative candidate genes in cattle, pigs, and sheep. Selection of cohorts of cows for SNP chip analysis was such that cohorts with extreme frequencies of disorders and cohorts with slightly deviating housing systems were excluded in this first step. The results from a mixed threshold model analysis with genotype included as a fixed effect and accounting for relationships among animals revealed that the intronic SNP rs29017173 (A/G) within the IQ motif-containing GTPase-activating protein 1 (IQGAP1, Bos taurus autosome 21) was significantly associated with disorder status. Back-transformed means of disorder status for the 3 genotypes were 0.37 (AA), 0.52 (AG), and 0.56 (GG). Using the full data set of 1,962 cows, including the less-suitable cohorts, gave back-transformed means of 0.51 (AA), 0.58 (AG), and 0.62 (GG). As SNP rs29017173 is included on the Illumina BovineSNP50 DNA Analysis BeadChip (Illumina Inc., San Diego, CA), a sample of 2,394 artificial insemination sires from the German calibration sample for genomic selection from birth years 1998 to 2003 was studied for possible correlated effects. The A/G polymorphism of SNP rs29017173 studied here was also associated with substantial effects for feet and leg traits from the classical conformation score system. Selection using this polymorphism will be facilitated by the fact that the same allele is favored for all traits with substantial effects.

Put your money where your mouth is

An effective herd health program fulfills the same goals, regardless of the herd size and species. As a veterinarian, our goal is to educate clients and producers on how to implement a working management program that meets the needs of the animals and owners. Cost and ease of implementation are the 2 factors that are of greatest concern in any herd. While herds vary from small backyard herds to large commercial herds, the goal should be the same-maximize production, efficiency, and profits while minimizing disease, medications given, and involuntary culls. Large herds have different challenges due to less single-animal attention and a need for a total herd approach.