New phenotypes for new breeding goals in dairy cattle

Cattle production faces new challenges regarding sustainability with its three pillars - economic, societal and environmental. The following three main factors will drive dairy cattle selection in the future: (1) During a long period, intensive selection for enhanced productivity has deteriorated most functional traits, some reaching a critical point and needing to be restored. This is especially the case for the Holstein breed and for female fertility, mastitis resistance, longevity and metabolic diseases. (2) Genomic selection offers two new opportunities: as the potential genetic gain can be almost doubled, more traits can be efficiently selected; phenotype recording can be decoupled from selection and limited to several thousand animals. (3) Additional information from other traits can be used, either from existing traditional recording systems at the farm level or from the recent and rapid development of new technologies and precision farming. Milk composition (i.e. mainly fatty acids) should be adapted to better meet human nutritional requirements. Fatty acids can be measured through a new interpretation of the usual medium infrared spectra. Milk composition can also provide additional information about reproduction and health. Modern milk recorders also provide new information, that is, on milking speed or on the shape of milking curves. Electronic devices measuring physiological or activity parameters can predict physiological status like estrus or diseases, and can record behavioral traits. Slaughterhouse data may permit effective selection on carcass traits. Efficient observatories should be set up for early detection of new emerging genetic defects. In the near future, social acceptance of cattle production could depend on its capacity to decrease its ecological footprint. The first solution consists in increasing survival and longevity to reduce replacement needs and the number of nonproductive animals. At the individual level, selection on rumen activity may lead to decreased methane production and concomitantly to improved feed efficiency. A major effort should be dedicated to this new field of research and particularly to rumen flora metagenomics. Low input in cattle production is very important and tomorrow's cow will need to adapt to a less intensive production environment, particularly lower feed quality and limited care. Finally, global climate change will increase pathogen pressure, thus more accurate predictors for disease resistance will be required.     

Prospecting candidate SNPs for backfat in Canchim beef cattle

Canchim is a composite cattle breed developed in Brazil for beef production. One of the breeding objectives is to increase fat deposition. QTLs for fat thickness and/or marbling have been reported on BTA4 and BTA14. The IGFBP3 and DDEF1 genes, mapped to BTA4 and BTA14, respectively, affect adipogenesis. We looked for SNPs in the IGFBP3 and DDEF1 genes that could be associated with backfat thickness in Canchim beef cattle. For SNP identification, sires with the highest accuracy were ranked according to expected breeding value for fat thickness; the 12 extremes (six sires with the highest and six with the lowest expected breeding value for the trait) were chosen. Six regions of the IGFBP3 and 14 regions of the DDEF1 were sequenced using the Sanger method. Nine SNPs were identified in IGFBP3 and 76 in the DDEF1. After an initial analysis, two SNPs were selected to be genotyped for the whole population; these were DDEF1g.279401A>G and IGFBP3c.4394T>C(Trp>Arg). We found a significant effect (P ≤ 0.05) of allele substitution on backfat thickness; however, the IGFBP3 SNP did not significantly affect this trait.     

Fixed-time artificial insemination in beef cattle

Background  

The study was designed to test the effect of fixed-time artificial insemination (fixed-AI) after the slightly modified Ovsynch protocol on the pregnancy rate in beef cattle in Finnish field conditions. The modification was aimed to optimize the number of offsprings per AI dose.     

Endometrial suppressor cells in beef cattle

Endometrial cells were recovered post mortem from cyclic and pregnant crossbred beef cattle (n = 5 each) on Days 16 to 18 after estrus, and were evaluated for their ability to suppress lymphocyte responses and release suppressor factor into the culture medium. The suppressor factor was assessed for transforming growth factor-beta (TGF-beta) activity. In addition, Percoll was used to fractionate endometrial cells from Angus cows (n = 4) on Days 16 to 18 of pregnancy to determine the density of the suppressor cells. Endometrial cells from cyclic and pregnant cows suppressed lymphocyte proliferative responses and released suppressor factor into the culture medium. The suppressor factor exhibited TGF-beta activity. Suppressor activities tended to be greatest for fractionated cells with densities of 1.01 and 1.095 g/mL. In conclusion, the bovine endometrium contains low- and high-density suppressor cells capable of releasing suppressor factor. The factor seems to be associated with TGF-beta.     

Quantitative trait loci for male reproductive traits in beef cattle

The objective of the present study was to detect quantitative trait loci (QTL) for male reproductive traits in a half-sib family from a Bos indicus (Brahman) x Bos taurus (Hereford) sire. The sire was mated with MARC III (1/4 Hereford, 1/4 Angus, 1/4 Red Poll and 1/4 Pinzgauer) cows. Testicular traits were measured from 126 male offspring born in 1996 and castrated at 8.5 months. Traits analysed were concentration of follicle stimulating hormone in peripheral blood at castration (FSH), paired testicular weight (PTW) and paired testicular volume (PTV) adjusted for age of dam, calculated age at puberty (AGE), and body weight at castration (BYW). A putative QTL was observed for FSH on chromosome 5. The maximum F-statistic was detected at 70 cM from the beginning of the linkage group. Animals inheriting the Hereford allele had a 2.47-ng/ml higher concentration of FSH than those inheriting the Brahman allele. Evidence also suggests the existence of a putative QTL on chromosome 29 for PTW, PTV, AGE and BYW. The maximum F-statistic was detected at cM 44 from the beginning of the linkage group for PTW, PTV and AGE, and at cM 52 for BYW. Animals that inherited the Brahman allele at this chromosomal region had a 45-g heavier PTW, a 42-cm(3) greater PTV, a 39-day younger AGE and a 22.8-kg heavier BYW, compared with those inheriting the Hereford allele. This is the first report of QTL for male reproductive traits in cattle.     

Effects of Fermenten supplementation to beef cattle

Two experiments were conducted to evaluate a commercially available supplemental N source for beef cattle (Fermenten^®; Church & Dwight Co., Inc., Princeton, NJ, USA). The first experiment evaluated kinetics of in vitro NH₃-N release using batch cultures of rumen fluid incubated with: control (no N added), soybean meal, urea, and Fermenten^®. Ammonia-N was measured at 0, 0.5, 2, 4, 6, 8, 12 and 24 h after incubation began. A treatment by time interaction (P<0.01) occurred in which, during the initial 2 h, Fermenten^® cultures had the highest (P<0.01) NH₃-N but, from 4 to 24 h, the highest (P<0.01) NH₃-N concentrations were with urea-incubated cultures. The total increase in NH₃-N concentrations from 0 to 24 h of incubation was less for Fermenten^® (P<0.01) than for the soybean meal and urea. The second experiment assessed effects of Fermenten^® supplementation on growth, blood parameters, voluntary forage intake and reproductive performance of beef heifers. Sixty heifers, stratified by initial body weight (BW), were randomly allocated to one of two treatments that consisted of iso-nitrogenous grain-based supplements containing either Fermenten^® (72 g/kg, as-fed) or urea (9.7 g/kg, as-fed). Supplements were offered three times weekly at a rate of 2.4 kg of dry matter per heifer daily. Shrunk BW was measured on days 0 and 112 for calculation of daily body weight gain. Body volume measurements were completed on days 0, 28, 56, 84 and 112, whereas pelvic area was assessed on days 0, 56 and 112. Blood samples were collected on days 28, 56, 84 and 112 for analysis of metabolites and hormones. On day 56, 2 heifers, which were randomly selected from each pasture, were placed in individual feeding stations for 26 days to determine treatment effects on voluntary forage intake. On day 112, all heifers were grouped by treatment and exposed to bulls for 60 days. Fewer heifers offered the Fermenten^® supplement attained puberty (P<0.05) and became pregnant during the study compared to heifers fed urea (0.60 and 0.93, respectively; P<0.01). Addition of Fermenten^® to batch cultures of rumen fluid rapidly increased NH₃-N concentrations, whereas further increases occurred in a slower and steady rate. Beef heifers fed a supplement containing Fermenten^® had similar growth and development, but inferior reproductive performance, than heifers fed a supplement containing urea.     

Postpartum fertility in beef cattle producing twins

Postpartum fertility was measured in 42 plur iparous Hereford cows and first calf Hereford heifers that calved after embryo transfer to induce twins. Dams were exposed to a Hereford bull from 4: 00 P.M. to 8:00 A.M. each day from 60 days postpartum until pregnancy was confirmed or calves were weaned at 180 days of age. Days open ($\text{X}\text{± SE}$) for dams that produced single and twin calves were 84.1 ± 4.6 (n = 12) and 94.9 ± 6.2 (n = 30), respectively. Corresponding values for dams that nursed one calf, including six females that lost one calf of a twin set at birth, and dams that nursed twins were 89.3 ± 6.4 (n = 18) and 93.4 ± 8.5 (n = 24). No significant differences were observed due to calving or suckling twin calves. Heifers that calved twins had a shorter mean interval to conception than cows that calved twins. These results are interpreted to mean that with proper management during the prepartum and postpartum periods, reduced fertility in beef cattle that produce twins need not occur.     

Breeding cattle and sheep for resistance to gastrointestinal nematodes

Gastrointestinal nematodes are an important cause of reduced production of meat, milk and wool in domestic livestock. It is generally believed that problems caused by these parasites have increased owing to the intensification of animal husbandry(1-3) of resistance to anthelmintics, current research is focussed on alternative control strategies that do not rely on anthelmintics. Here, Bram Kloosterman, Henk Parmentier and Harm Ploeger review work on the genetic resistance of domestic ruminants to these nematodes and discuss the practicality of breeding programmes.     

Chronic shedding of Campylobacter species in beef cattle

AIMS: To determine the prevalence of chronic shedding of Campylobacter species by beef cattle, a longitudinal study of shedding patterns was conducted in a cohort of 60 beef steers over a 4-month period. METHODS AND RESULTS: Steers were maintained in a simulated feedlot setting but individually in pens to minimize transmission among animals. At each collection time, campylobacters in faeces were detected using conventional PCR. In addition, quantities of Campylobacter jejuni and C. lanienae in faeces were measured using real-time quantitative (RTQ) PCR. All of the steers tested shed Campylobacter species during the course of the study, and overall, 90% of the 299 samples tested were positive for Campylobacter DNA. The majority of the animals (86%) shed campylobacters at >/=4 sample times. The most prevalent taxon detected in bovine faeces was C. lanienae (56% of samples) followed by C. jejuni (13%), C. hyointestinalis (8%), and C. fetus (2%). No C. coli was detected, and 13% of the faecal samples contained two or more of the above species. Seven (12%) and 34 (57%) animals shed C. jejuni and C. lanienae at >/=3 sample times, respectively. For both C. lanienae and C. jejuni, a substantial number of cells were detected in faeces using RTQ-PCR; 27% of the samples positive for C. jejuni contained populations >10(4) cells g(-1) (maximum of 5 x 10(5) cells g(-1)), and 44% of samples positive for C. lanienae possessed populations >10(6) cells g(-1) (maximum of 4 x 10(8) cells g(-1)). A significant correlation was observed between shedding of C. lanienae and the severity of liver abscesses. In 27% of the samples, an amplicon was obtained for genus-specific but not for the species-specific primers. Sequencing of the partial 16S rRNA gene suggested the presence of at least two undescribed Campylobacter species but this has yet to be confirmed. CONCLUSIONS: A high percentage of feedlot cattle shed large quantities of Campylobacter species in their faeces over a protracted period of time (ca 112 days). SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study of longitudinal shedding patterns of campylobacters in beef cattle using PCR-detection methods. In addition, this is the first use of RTQ-PCR to directly quantify C. jejuni or C. lanienae in faeces. The results of the study show that a large number of cattle (>85%) chronically shed campylobacters in feedlots.     

Association of leptin genotypes with beef cattle characteristics

A single nucleotide polymorphism (C/T) in bovine leptin, resulting in an arginine to cysteine amino acid substitution (p.Arg25Cys), has previously been shown to have an impact on carcass characteristics. Given the significant energetic relationship between fat and animal efficiency, further evaluation of this SNP across larger animal populations is warranted. Of the total number of 136 286 genotyped cattle in this study, 92 112 and 53 189 were analysed for backfat and body weight measurements, respectively. Results showed a significant positive relationship (P < 0.0001) between the T allele frequency and animal backfat, with TT, CT and CC animals having estimates of 6.79 ± 0.02, 6.49 ± 0.01 and 6.28 ± 0.01 mm, respectively. Calculations using rate of backfat accretion showed that animals with CC genotypes would require more days to reach 12 mm of backfat (45 days) than animals with CT (42 days) and TT (38 days) genotypes. Animal weight was also shown to be positively associated (P < 0.0001) with genotype, as animals of the TT, CT and CC genotypes weighed 484.2 ± 0.7, 488.0 ± 0.5 and 487.3 ± 0.6 kg, respectively, further underscoring the effects of this SNP on key market cattle characteristics.     

Pedigree analysis of eight Spanish beef cattle breeds

The genetic structure of eight Spanish autochthonous populations (breeds) of beef cattle were studied from pedigree records. The populations studied were: Alistana and Sayaguesa (minority breeds), Avileña – Negra Ibérica and Morucha ("dehesa" breeds, with a scarce incidence of artificial insemination), and mountain breeds, including Asturiana de los Valles, Asturiana de la Montaña and Pirenaica, with extensive use of AI. The Bruna dels Pirineus breed possesses characteristics which make its classification into one of the former groups difficult. There was a large variation between breeds both in the census and the number of herds. Generation intervals ranged from 3.7 to 5.5 years, tending to be longer as the population size was larger. The effective numbers of herds suggest that a small number of herds behaves as a selection nucleus for the rest of the breed. The complete generation equivalent has also been greatly variable, although in general scarce, with the exception of the Pirenaica breed, with a mean of 3.8. Inbreeding effective population sizes were actually small (21 to 127), especially in the mountain-type breeds. However, the average relatedness computed for these breeds suggests that a slight exchange of animals between herds will lead to a much more favourable evolution of inbreeding. The effective number of founders and ancestors were also variable among breeds, although in general the breeds behaved as if they were founded by a small number of animals (25 to 163).     

Mitochondrial DNA polymorphisms and fertility in beef cattle

Four hundred and twenty-two beef cattle of two different breeds (purebred Hereford and composite multibreed) were characterized by polymerase chain reaction-restriction fragment length polymorphism, using the restriction enzymes ApaI, AvaII, HindIII, PstI, SpeI, SspI and TaqI in two regions (the D-loop and the ND-5 gene) of mitochondrial DNA. The association between molecular haplotypes and records on calving rate, defined as the mean number of live calves born per year over 4 years, were examined by analysis of variance. A significant association was found between calving rate and mitochondrial polymorphisms in both breeds. This may have implications for genetically improving cow fertility.     

Social organization among young beef cattle in confinement

Social organization or dominance hierarchies were demonstrated among beef steers as young as 250 days of age. Two groups of five and seven crossbred beef steers were scored for agonistic encounters, and these data were used to determine dominant—subordinate relationships. The effects of removing and adding animals to groups were determined by mixing some members from the groups of five and adding new members to obtain the groups of seven. Weight was positively correlated (P< 0.05) with dominance value (0.55). There was evidence that the dominance orders were formed soon after weaning and that the orders remained stable even when the groups were moved to other pens.     

Genetic disorders in beef cattle: a review

The main purpose of present review is to describe and organize autosomal recessive disorders (arachnomelia, syndactylism, osteopetrosis, dwarfism, crooked tail syndrome, muscular hyperplasia, glycogen storage disease, protoporphyria), which occur among beef cattle, and methods that can be applied to detect these defects. Prevalence of adverse alleles in beef breeds happens due to human activity—selections of favorable features, e.g. developed muscle tissue. Unfortunately, carriers of autosomal recessive diseases are often characterized by these attributes. Fast and effective identification of individuals, that may carry faulty genes, can prevent economical losses.