The Effect of Genetic Merit and Production System on Dairy Cow Fertility, Measured Using Progesterone Profiles and On-Farm Recording

Genome-wide association studies for difficult-to-measure traits are generally limited by the sample population size with accurate phenotypic data. The objective of this study was to utilise data on primiparous Holstein-Friesian cows from experimental farms in Ireland, the United Kingdom, the Netherlands and Sweden to identify genomic regions associated with traditional measures of fertility, as well as a fertility phenotype derived from milk progesterone profiles. Traditional fertility measures investigated were days to first heat, days to first service, pregnancy rate to first service, number of services and calving interval (CI); post-partum interval to the commencement of luteal activity (CLA) was derived using routine milk progesterone assays. Phenotypic and genotypic data on 37 590 single nucleotide polymorphisms (SNPs) were available for up to 1570 primiparous cows. Genetic parameters were estimated using linear animal models, and univariate and bivariate genome-wide association analyses were undertaken using Bayesian stochastic search variable selection performed using Gibbs sampling. Heritability estimates of the traditional fertility traits varied from 0.03 to 0.16; the heritability for CLA was 0.13. The posterior quantitative trait locus (QTL) probabilities, across the genome, for the traditional fertility measures were all ,0.021. Posterior QTL probabilities of 0.060 and 0.045 were observed for CLA on SNPs each on chromosome 2 and chromosome 21, respectively, in the univariate analyses; these probabilities increased when CLA was included in the bivariate analyses with the traditional fertility traits. For example, in the bivariate analysis with CI, the posterior QTL probability of the two aforementioned SNPs were 0.662 and 0.123. Candidate genes in the vicinity of these SNPs are discussed. The results from this study suggest that the power of genome-wide association studies in cattle may be increased by sharing of data and also possibly by using physiological measures of the trait under investigation.Keywords: genome-wide association, fertility, cow, progesterone ImplicationsTraditional genetic selection for fertility is made difficult by the low heritability of traditional fertility phenotypes. This limitation can be minimised by increasing the heritability of the trait(s) or by using genomic information that explains a large proportion of the genetic variation in fertility. In the present study, both approaches were investigated. Heritability estimates greater than some traditional fertility traits were observed for the post-partum commencement of luteal activity quantified using milk progesterone concentration. Specific regions of the genome associated with fertility were also observed, albeit they only explained a small proportion of the total genetic variance in the traits.

Section: Discussionsupporting

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Genome-wide associations for fertility traits in Holstein–Friesian dairy cows using data from experimental research herds in four European countries

Berry

Bastiaansen

Veerkamp

et al. 2012

“…More than 25% of cows show a prolonged luteal phase. This is consistent with a higher incidence of short C-LA as the cows experiencing a shorter interval to C-LA are more likely to experience a longer first luteal phase (Royal et al, 2002;Grimard and Disenhaus, 2005;Horan et al, 2005;Petersson et al, 2007;Pollott and Coffey, 2008). The extent to which this effect has a genetic basis is not clear.…”

Section: Milk Production and Reproductive Performancementioning

confidence: 80%

Nutritional sub-fertility in the dairy cow: towards improved reproductive management through a better biological understanding

Friggens

Disenhaus

Petit

2010

There has been a significant decline in the reproductive performance of dairy cattle in recent decades. Cows, take longer time to return to the oestrus after calving, have poorer conception rates, and show fewer signs of oestrus. Achieving good reproductive performance is an increasing challenge for the dairy producer. In this study we focus on understanding the overall biological phenomena associated with nutritional sub-fertility rather than the underlying multiplicity of physiological interactions (already described in a number of recent studies). These phenomena are important because they represent the natural adaptations of the animal for dealing with variations in the nutritional environment. They can also be used to monitor and modulate reproductive performance on-farm. There is an underlying trade-off between two aspects of reproduction: investment in the viability of the current calf and investment in future offspring. As the investment in, and viability of, the current calf is related to maternal milk production, we can expect that level of milk production per se has effects on subsequent reproductive performance (investment in future offspring). Lactating cows have a lower proportion of viable embryos, which are of poorer quality, than do non-lactating cows. The same applies to high-compared to medium-genetic merit cows. Another important biological property is the adaptive use of body reserves in support of reproduction. Orchestrated endocrine changes in pregnancy and lactation facilitate the deposition of body lipid during pregnancy and mobilisation in early lactation. When the cow fails to accumulate the reserves she needs to safeguard reproduction she delays committing to further reproductive investment. But how does the cow 'know' that she is failing in energy terms? We argue that the cow does this by 'monitoring' both the body fat mobilisation and body fatness. Excessive body fat mobilisation indicates that current conditions are worse than expected. Body fatness indicates the future ability of the cow to safeguard her reproductive investment is compromised. Both delay further reproductive commitment. The relationship between reproductive performance and; milk production as an index of maternal investment, body fatness as an index of ability to safeguard reproductive investment, and body fat mobilisation as an index of the current nutritional environment -are examined. Nutritional strategies that seek to modulate body mobilisation and the endocrine environment by use of glucogenic and lipogenic diets, and the use of in-line progesterone profiles to monitor reproductive status are then discussed in this biological context.

“…The cattle were housed at Langhill Farm, Roslin, Midlothian (55°52'1"N, 3°10'15"W), hereafter 'Farm 1', until late June 2002 and then transferred to Crichton Royal Farm, Dumfries (55°02' N, 3°34' W), 'Farm 2', a distance of 95 km. The management systems are described for Farm 1 in Veerkamp et al (1994) and for Farm 2 in Pollott and Coffey (2008). Briefly, two genetic lines were created in 1976: select (S) and control (C).…”

Section: Methodsmentioning

confidence: 99%

Dairy cattle in a temperate climate: the effects of weather on milk yield and composition depend on management

Hill

Wall

2015

114

A better understanding of how livestock respond to weather is essential to enable farming to adapt to a changing climate. Climate change is mainly expected to impact dairy cattle through heat stress and an increase in the frequency of extreme weather events. We investigated the effects of weather on milk yield and composition (fat and protein content) in an experimental dairy herd in Scotland over 21 years. Holstein Friesian cows were either housed indoors in winter and grazed over the summer or were continuously housed. Milk yield was measured daily, resulting in 762 786 test day records from 1369 individuals, and fat and protein percentage were sampled once a week, giving 89 331 records from 1220 cows/trait. The relative influence of 11 weather elements, measured from local outdoor weather stations, and two indices of temperature and humidity (THI), indicators of heat stress, were compared using separate maximum likelihood models for each element or index. Models containing a direct measure of temperature (dry bulb, wet bulb, grass or soil temperature) or a THI provided the best fits to milk yield and fat data; wind speed and the number of hours of sunshine were most important in explaining protein content. Weather elements summarised across a week's timescale from the test day usually explained milk yield and fat content better than shorter-scale (3 day, test day, test day −1) metrics. Then, examining a subset of key weather variables using restricted maximum likelihood, we found that THI, wind speed and the number of hours of sunshine influenced milk yield and composition. The shape and magnitude of these effects depended on whether animals were inside or outside on the test day. The milk yield of cows outdoors was lower at the extremes of THI than at average values, and the highest yields were obtained when THI, recorded at 0900 h, was 55 units. Cows indoors decreased milk yield as THI increased. Fat content was lower at higher THIs than at intermediate THIs in both environments. Protein content decreased as THI increased in animals kept indoors and outdoors, and the rate of decrease was greater when animals were outside than when they were inside. Moderate wind speeds appeared to alleviate heat stress. These results show that milk yield and composition are impacted at the upper extreme of THI under conditions currently experienced in Scotland, where animals have so far experienced little pressure to adapt to heat stress.Keywords: climate change, fat percentage, heat stress, protein percentage, THI ImplicationsClimate change is expected to bring about drier, hotter summers and an increased frequency of extreme weather events across Europe. Here we show that milk yield and quality decline at the upper extremes of temperature and humidity even under conditions currently experienced in Scotland. We identify the values of temperature and humidity, and of other weather elements, at which performance begins to decrease. These estimates could be used in conjunction with climate projections to help policy makers un...