Impact of Brahman genetics on skin histology characteristics with implications for heat tolerance in cattle.

Cattle lose heat predominantly through cutaneous evaporation at the skin-hair coat interface when experiencing heat stress. Sweating ability, sweat gland properties, and hair coat properties are a few of the many variables determining the efficacy of evaporative cooling. Sweating is a significant heat dissipation mechanism responsible for 85% of body heat loss when temperatures rise above 86⁰F.

The effect of Brahman genes on body temperature plasticity of heifers on pasture under heat stress.

Bos taurus indicus cattle have the superior ability for the regulation of body temperature during heat stress due to a number of physiological and cellular level adaptive traits. The objectives of this study were to quantify the change in body temperature in heifers with various proportions of Brahman genes per unit increase in heat stress as measured by temperature-humidity index (THI) and to assess how different breed groups responded to varying intensity and duration of heat stress. A total of 299 two-yr-old heifers from six breed groups ranging from 100% Angus to 100% Brahman were evaluated under hot and humid conditions during 2017 and 2018 summer days.

Genetic parameters for hair characteristics and core body temperature in a multibreed Brahman-Angus herd1.

Thermal stress in hot humid conditions limits cattle production. The objectives for this study were to estimate genetic parameters for hair characteristics and core body temperature under low and high temperature humidity index (THI) conditions. Hair samples were collected and measured for length and diameter.

Thermoregulatory response of Brangus heifers to naturally occurring heat exposure on pasture.

Heat stress is a cause of major economic losses to cattle producers, especially in tropical and subtropical environments. The objectives of this study were to assess the phenotypic variability in core body temperature and sweating rate and to evaluate the effect of coat type, temperament, and BW on core body temperature and sweating rate in Brangus heifers. During August and September of 2016, 725 Brangus heifers were evaluated on pasture in four separate groups (n = 200, 189, 197, and 139).

Strategies to predict and improve eating quality of cooked beef using carcass and meat composition traits in Angus cattle.

Product quality is a high priority for the beef industry because of its importance as a major driver of consumer demand for beef and the ability of the industry to improve it. A 2-prong approach based on implementation of a genetic program to improve eating quality and a system to communicate eating quality and increase the probability that consumers' eating quality expectations are met is outlined. The objectives of this study were 1) to identify the best carcass and meat composition traits to be used in a selection program to improve eating quality and 2) to develop a relatively small number of classes that reflect real and perceptible differences in eating quality that can be communicated to consumers and identify a subset of carcass and meat composition traits with the highest predictive accuracy across all eating quality classes.

Effect of prolactin, beta-lactoglobulin, and kappa-casein genotype on milk yield in East Friesian sheep.

The effect of prolactin (PRL), beta-lactoglobulin (beta-LG), and kappa-casein (CSN3) on milk yield was estimated in an East Friesian dairy sheep population from Old Chatham Sheepherding Company, New York. Genotypes were determined by PCR amplification followed by digestion with HaeIII and RsaI for PRL and beta-LG, respectively, and by PCR amplification for CSN3. Monthly milking records and pedigree information were used to evaluate the effect of each polymorphism on milk yield.

Rearing conditions, morbidity and breeding performance in dairy heifers in southwest Sweden.

We carried out a longitudinal study of 122 dairy herds in southwest Sweden to investigate relationships of rearing conditions and health with heifer breeding performance and to estimate the incidence of clinical diseases and survival until 1st calving. A total of 3081 animals born in 1998 (47% Swedish Red; 50% Swedish Holstein breed) were followed from birth until calving, culling or death. Information about housing, management, breeds and dates of birth, breeding and calving was obtained from farmers.

Fertility responses of Mexican Holstein cows to US sire selection.

Genetic relationships between 2 fertility traits and milk production were investigated using mature-equivalent lactation records of 55,162 daughters of 1,339 Holstein sires in Mexico and 499,401 daughters of 663 Holstein sires in the northeastern United States. Data sets contained yields in first and second lactation, age at first calving (AFC), and calving interval (CI). There were 474 US sires in common between countries.

Morbidity in 3-7-month-old dairy calves in south-western Sweden, and risk factors for diarrhoea and respiratory disease.

The health status of 2947 heifer calves born in 1998 and raised in 122 Swedish dairy herds was monitored from birth to 210 days of age. Disease occurrence was recorded by farmers and by veterinarians who visited the farms six times yearly, examined the calves clinically and auscultated their lungs. The incidence risks of diarrhoea, ringworm and clinical respiratory-tract disease (CRTD) in calves from 3 to 7 months of age were 2.

Selection for increased production and the welfare of dairy cows: are new breeding goals needed?

In many European countries, milk production per cow has more than doubled in the last 40 years. The increase in production has been accompanied by declining ability to reproduce, increasing incidence of health problems, and declining longevity in modern dairy cows. Genetic selection for increased milk yield increasingly is viewed as increasing profit at the expense of reducing animal welfare.

Herd-level risk factors for infectious diseases in Swedish dairy calves aged 0-90 days.

The effect of environmental factors and management routines on the risk of diarrhoea, respiratory disease and other infectious diseases was investigated in 3081 heifer calves 0-90 days old in 122 Swedish dairy herds. The farmers kept records on cases of diseases in their heifer calves and in addition, project veterinarians clinically examined all calves every 2-3 months. At each visit, the veterinarians also measured the ammonia concentration and relative air humidity in the housing facilities for the calves.

Effects of diseases on reproductive performance in Swedish Red and White dairy cattle.

The objectives of this study were to evaluate the effect of diseases on days open (DO), days to first breeding (DFB) and days from first breeding to conception (DFBC) using survival analysis models, and to assess the significance of the sire component and its possible confounding effect. The data consisted of a random sample of 20% of all herds enrolled in Swedish recording system and using 100% artificial insemination with at least 15 Swedish Red and White cows calving in 1991. The follow-up period was from 45 to 145 d after calving.

Genotype by environment interaction for yield and somatic cell score with alternative environmental definitions.

Differential genetic expression in high and low opportunity Sicilian Holstein-Friesian and Brown Swiss herd environments was investigated using endogenous and exogenous variables in a set of three definitions. Results of genetic by environmental interaction were compared using alternative environmental definitions: within herd-year standard deviation for mature equivalent milk yield (HYSD), detectable incidence of normal vs. abnormal (peakless) lactation and herds clustered by causal relationships from high and low frequency use of nutrition, milking, health and animal handling practices.

Dam-related effects on heart girth at birth, morbidity and growth rate from birth to 90 days of age in Swedish dairy calves.

We investigated the effects of dam-related factors (such as calving performance, milk leakage, diseases, milk production, and somatic-cell count (SCC)) on heart girth at birth and the incidence risk of diarrhoea and respiratory disease during the first 90 days in Swedish dairy calves. The effects of these dam-related factors and environmental and management-related (but not dietary) factors on the calves' growth rate during the first 90 days of life also were analysed. The study used nearly 3,000 heifer calves born in 1998 on 122 farms in the south-west of Sweden.

Heritability of plasma von Willebrand factor antigen concentration in German Wirehaired pointers.

We applied quantitative genetic analyses to a population of German Wirehaired pointer dogs affected with type 2 von Willebrand disease. Plasma von Willebrand factor (vWF) protein concentration measured as vWF antigen (vWF:Ag), clinical history, and pedigree data were compiled for 331 dogs over a 5-year test period. Eight dogs had histories of abnormal bleeding and had markedly decreased plasma vWF:Ag concentrations (<1%).

Genetic analysis of Holstein cattle populations in Brazil and the United States.

Genetic relationships between Brazilian and US Holstein cattle populations were studied using first-lactation records of 305-d mature equivalent (ME) yields of milk and fat of daughters of 705 sires in Brazil and 701 sires in the United States, 358 of which had progeny in both countries. Components of(co)variance and genetic parameters were estimated from all data and from within herd-year standard deviation for milk (HYSD) data files using bivariate and multivariate sire models and DFREML procedures distinguishing the two countries. Sire (residual) variances from all data for milk yield were 51 to 59% (58 to 101%) as large in Brazil as those obtained from half-sisters in the average US herd.

Effect of herd environment on the genetic and phenotypic relationships among milk yield, conception rate, and somatic cell score in Holstein cattle.

A total of 248,230 primiparous records of Holstein cows calving from 1987 to 1994 (daughters of 588 sires in 3042 herds) was used to evaluate potential genotype by environment interactions among mature equivalent milk yield, lactation mean somatic cell score, and conception rate at first service. Herds were classified into low and high environmental groups using three different criteria: standard deviation of herd mature equivalent milk yield, a combination of herd mature equivalent milk yield mean and standard deviation, and the herd mean of body weight at first calving divided by age at first calving. Genetic parameters were modeled by using multiple-trait linear mixed models and were fitted using the multiple-trait derivative-free software.

Interaction between milk yield of Holstein cows in Mexico and the United States.

Genotype by environment interaction for milk yield was investigated by analyzing 55,162 mature equivalent, first lactation records of daughters from 1339 Holstein sires in Mexico and 499,401 daughters from 663 Holstein sires in the northeastern US. There were 474 US sires in common. Herd-year standard deviation was used to define non-overlapping high (> or = 1600 kg) and low (< or = 1300 kg) Mexican environments and a low (< or = 1025 kg) US environment.

Associations between use of electric cow-trainers and clinical diseases, reproductive performance and culling in Swedish dairy cattle.

The aims of this follow-up study were: (a) to evaluate the role of ECT technology as a risk factor for several diseases; and (b) to determine if the effects of these diseases on cows' reproductive performance and as risk factors for culling are influenced by exposure to ECTs. Diseases considered were retained placenta, metritis, ketosis, cystic ovaries, silent heat, milk fever, clinical mastitis, and foot and leg problems. We used historical and contemporary controls (with control herds selected to match the experimental herds for size and location).

Assessment of the dairy production needs of cattle owners in southeastern Sicily.

This study was undertaken to investigate research and outreach priorities for Progetto Ibleo (Project Ibleo), a center created in 1990 with tripartite government funding to serve dairy producers in the Hyblean region of Sicily. Data comprised values for production and composition of milk from 1984 to 1989 from 35 herds of Modicana cows on a system based on pasture and that from 69 input-intensive herds of Holstein cows, associated lactation and reproduction measures, and yield and composition of forages from 4 of these farms in 1988. Season had a large effect on the neutral detergent fiber and crude protein composition of forages, production and composition of milk, and predicted yield of fresh Ragusano cheese manufactured from the milk of these cows.

Incidences and effects of diseases on the performance of Swedish dairy herds stratified by production.

Incidences of diseases and their effects on reproductive performance and risk of culling in herds stratified by production and estrus detection efficiency were studied. Data were from the Swedish milk and disease recording systems and consisted of records for 33,748 first parity Swedish Friesian cows. A standardized mixed threshold model was used for statistical analyses of categorical outcome variables, and an ordinary linear mixed model was used for continuous outcome variables.

Design and validation of a dynamic discrete event stochastic simulation model of mastitis control in dairy herds.

A dynamic stochastic simulation model for discrete events, SIMMAST, was developed to simulate the effect of mastitis on the composition of the bulk tank milk of dairy herds. Intramammary infections caused by Streptococcus agalactiae, Streptococcus spp. other than Strep.

A simulation of strategies to lower bulk tank somatic cell count below 500,000 per milliliter.

In the future, the Pasteurized Milk Ordinance may make milk quality standards more stringent by lowering the somatic cell count (SCC) limit on Grade A raw milk to 500,000/ml. Therefore, using a discrete event simulation model, we investigated the effects of the prevention of intramammary infection (as recommended by the National Mastitis Council), lactation therapy, and dry cow therapy (all seven possible combinations) on bulk tank SCC; milk, fat, and protein yields; prevalence of intramammary infection; and culling for mastitis. Untreated controls were also tested.

Selecting linear-score distributions for modelling milk-culture results.

The data for this cross-sectional retrospective study are from surveys of 65 dairy-cattle herds in central New York, USA sampled between February, 1993 and March, 1995. The objective was to identify probability distributions of logarithmically transformed somatic-cell counts (linear score) for use in a simulation model of mastitis and milk quality. Probability density functions were estimated using maximum-likelihood estimators for the linear score of individual-cow composite-milk samples culture negative and culture positive for the pathogens Streptococcus agalactiae, Streptococcus non-agalactiae, Staphylococcus aureus, and coagulase-negative staphylococci for the complete dataset and by bulk-tank somatic-cell count group (< 500,000, > or = 500,000 SCC/ml).

Effects of season, herd size, and geographic region on the composition and quality of milk in the northeast.

Our objectives were to describe the milkshed comprising herds in New York, western New Jersey, and central and eastern Pennsylvania in regard to milk yield, composition, and quality and also to estimate the effects of season, herd size, and geographic area on those same variables. Data were collected from July 1993 through June 1994 from 3450 herds. The effect of a somatic cell count (SCC) limit of 500,000/ml on milk yield and the composition of monthly bulk tank milk for all marketed milk was estimated as was the frequency of deliveries of milk that contained SCC that were greater than this limit.