Heritability of hypocalcemia at first parturition in Norwegian cattle: genetic correlations with yield and weight

Additive genetic and heterosis effects for milk fever in a population of Jersey, Holstein × Jersey, and Holstein cattle under grazing conditions

The aim of this study was to estimate additive genetic and heterosis effects for milk fever (MF) in Costa Rican dairy cattle. A farm-based management information software was used to collect 223,783 parity records between years 1989 and 2016, from 64,008 cows, 2 breeds (Jersey, Holstein × Jersey crosses, and Holstein), and 134 herds. The pedigree file comprised 73,653 animals distributed across 10 generations. A total of 4,355 (1.95%) clinical cases of MF were reported within this population, affecting 3,469 (5.42%) cows. Data were analyzed using 2 animal models, both accounting for repeatability and assuming different distributions for MF event: normal (linear model) or binomial (threshold model). The models included parity as fixed effect, breed and heterosis as fixed regressions, and herd-year-season, additive genetic, and permanent environment as random effects. The models were fit using a generalized linear mixed model approach, as implemented in ASReml 4.0 software. We noted significant regression on the percentage of Holstein breed, depicting a -0.0086% [standard error (SE) = 0.0012] decrease in MF incidence for each 1-unit increase in percentage of Holstein breed. A favorable heterosis of 5.9% for MF was found, although this was not statistically significant. Heritability and repeatability were, respectively, 0.03 (SE = 0.002) and 0.05 (SE = 0.002) for the linear model, and 0.07 (SE = 0.007) and 0.07 (SE = 0.007) for the threshold model. The correlation between BLUP (all animals in pedigree) for linear and threshold models, was 0.89. The average accuracy of the estimated BLUP for all animals were 0.44 (standard deviation = 0.13) for the linear model and 0.29 (standard deviation = 0.14) for the threshold model. Heritability and repeatability for MF within this population was low, though significant.

Genetics of food intake, live weight, condition score and energy balance

The objectives of this study were to investigate genetic variation for traits that are part of the food utilization complex and to investigate the scope for future genetic improvement of traits possibly linked to metabolic stress: live weight (change), condition score (change) and energy balance. Many aspects of the food utilization complex appear to be heritable and are affected by genetic selection for yield. In general, genetic selection for yield increases intake and body tissue mobilization and energy balance is expected to decrease. However, unfavourable effects of genetic selection can be compensated for by measuring additional traits to be included in breeding programmes. Food intake, live weight (change) and condition score (change) are all potential options. Which traits should be measured, at what lactation stages and in which (nutritional) environment will merely depend on the coheritability with health and fertility, the genetic correlation with milk yield and the cost of measuring the trait effectively in a breeding programme.

[Factors influencing first-colostrum calcium concentration in Holstein-Friesian cows and the relationship to postpartum calcium concentration]

OBJECTIVE

To investigate the factors that affect the calcium content of the first colostrum (milk exclusively of the first withdrawal) and the relationship to the blood calcium concentration. We tested the hypotheses that the lactation number is the main influence factor and that there is a relationship to the postpartum serum calcium concentration.

MATERIAL AND METHODS

An observational study was conducted from April 2012 to March 2013 at a commercial dairy farm (2278 Holstein-Friesian cows). The analysis comprised the following variables: blood serum concentrations of calcium, phosphate, non-esterified fatty acids, and β-hydroxybutyrate; back-fat thickness; daily milk production; calving data; lactation number; male parent of the cow; length of gestation; age at first calving; dry-period duration; fertility parameters of prelactation; diseases during the dry period and up to 3 days postpartum. A stepwise analysis of the data for correlations and influencing factors was conducted by means of variance, correlation, and multiple linear regression analyses.

RESULTS

The mean calcium concentration of the colostrum was 2386 mg/l (standard deviation 550 mg/l), with heifers having a higher value by 148.5 mg/l than pluriparous cows. Factors influencing the colostrum calcium content were the mean milk production during the first week of lactation and the back-fat thickness at drying off. The correlation to the milk production was negative, which may be a dilution effect. An increase in back-fat thickness caused an increase in the colostrum calcium concentration. Together, these two factors explained 25% of the colostrum calcium variation. The lactation number and the blood calcium concentration were not significant influence factors on the colostrum calcium content.

CONCLUSION AND CLINICAL RELEVANCE

The hypotheses could not be confirmed in that there was neither a relationship of to the blood calcium concentration nor of the lactation number with the colostrum calcium content. The colostrum calcium content displayed a wide individual variation. However, there was a possible influence through milk production and back-fat thickness, but this would not be beneficial with regard to prophylaxis of parturient paresis.

Association between non-parturient post-partum hypocalcaemia and the interval from calving to first ovulation in Holstein-Friesian cows

This study was undertaken to quantify the effect of episodes of subclinical hypocalcaemia on the interval from calving to first ovulation. It incorporated three separate surveys during early lactation of 44 and 60 cows at Mutdapilly Research Station and 56 cows at Wollongbar Agricultural Institute. Twenty-five, 37 and 39% of cows respectively, experienced episodes later than 3 days after calving, of non-parturient post-partum hypocalcaemia, when plasma calcium concentration fell below 2⋅00 mmolll. Episodes of subclinical hypocalcaemia did not affect the interval to first post-partum ovulation in the two experiments conducted at Mutdapilly Research Station but ovulation was significantly delayed in cows that experienced episodes of subclinical hypocalcaemia at Wollongbar Agricultural Institute.

Invited review: Opportunities for genetic improvement of metabolic diseases

Metabolic disorders are disturbances to one or more of the metabolic processes in dairy cattle. Dysfunction of any of these processes is associated with the manifestation of metabolic diseases or disorders. In this review, data recording, incidences, genetic parameters, predictors, and status of genetic evaluations were examined for (1) ketosis, (2) displaced abomasum, (3) milk fever, and (4) tetany, as these are the most prevalent metabolic diseases where published genetic parameters are available. The reported incidences of clinical cases of metabolic disorders are generally low (less than 10% of cows are recorded as having a metabolic disease per herd per year or parity/lactation). Heritability estimates are also low and are typically less than 5%. Genetic correlations between metabolic traits are mainly positive, indicating that selection to improve one of these diseases is likely to have a positive effect on the others. Furthermore, there may also be opportunities to select for general disease resistance in terms of metabolic stability. Although there is inconsistency in published genetic correlation estimates between milk yield and metabolic traits, selection for milk yield may be expected to lead to a deterioration in metabolic disorders. Under-recording and difficulty in diagnosing subclinical cases are among the reasons why interest is growing in using easily measurable predictors of metabolic diseases, either recorded on-farm by using sensors and milk tests or off-farm using data collected from routine milk recording. Some countries have already initiated genetic evaluations of metabolic disease traits and currently most of these use clinical observations of disease. However, there are opportunities to use clinical diseases in addition to predictor traits and genomic information to strengthen genetic evaluations for metabolic health in the future.

Genetics of animal health and disease in cattle

There have been considerable recent advancements in animal breeding and genetics relevant to disease control in cattle, which can now be utilised as part of an overall programme for improved cattle health. This review summarises the contribution of genetic makeup to differences in resistance to many diseases affecting cattle. Significant genetic variation in susceptibility to disease does exist among cattle suggesting that genetic selection for improved resistance to disease will be fruitful. Deficiencies in accurately recorded data on individual animal susceptibility to disease are, however, currently hindering the inclusion of health and disease resistance traits in national breeding goals. Developments in 'omics' technologies, such as genomic selection, may help overcome some of the limitations of traditional breeding programmes and will be especially beneficial in breeding for lowly heritable disease traits that only manifest themselves following exposure to pathogens or environmental stressors in adulthood. However, access to large databases of phenotypes on health and disease will still be necessary. This review clearly shows that genetics make a significant contribution to the overall health and resistance to disease in cattle. Therefore, breeding programmes for improved animal health and disease resistance should be seen as an integral part of any overall national disease control strategy.

Investigation of major gene for milk yield, milking speed, dry matter intake, and body weight in dairy cattle

The main aim of this study was to determine if there exist any major gene for milk yield (MY), milking speed (MS), dry matter intake (DMI), and body weight (BW) recorded at various stages of lactation in first-lactation dairy cows (2543 observations from 320 cows) kept at the research farm of the Swiss Federal Institute of Technology between April 1994 and April 2004. Data were modelled based a simple repeatability covariance structure and analysed by using Bayesian segregation analyses. Gibbs sampling was used to make statistical inferences on posterior distributions; inferences were based on a single run of the Markov chain for each trait with 500,000 samples, with each 10th sample collected because of the high correlation among the samples. The posterior mean (+/-SD) of major gene variance was 2.61 (+/-2.46) for MY, 0.83 (+/-1.26) for MS, 4.37 (+/-2.34) for DMI, and 2056.43 (+/-665.67) for BW. Highest posterior density regions for 3 of the 4 traits did not include 0 (except MS), which supported the evidence for major gene. With additional tests for agreement with Mendelian transmission probabilities, we could only confirm the existence of a major gene for MY, but not for MS, DMI, and BW. Expected Mendelian transmission probabilities and their model fits were also compared.

A review of genetic resistance to disease in Bos taurus cattle

Cattle show considerable variability in their responses to a wide range of disease challenges, and much of the variability is genetic. This review highlights genetic variation in disease susceptibility in Bos taurus cattle, with variation found at the breed level and also within breeds. Disease challenges come from bacteria and viruses, parasites and feed-borne toxins. For an animal to survive, it needs its own mechanisms for resisting these challenges, or for being resilient to them, or it must be protected artificially from them. Disease challenges have been classified as 'diseases from without', but there is also another class of genetic diseases resulting from inborn errors of metabolism, which might be called 'diseases from within'. Degrees of inheritance (heritabilities) are reviewed for a range of economically important traits including resistance to mastitis, ketosis, lameness, nematode parasites, external parasites, eye disease, respiratory disorders, tuberculosis, brucellosis, Johne's disease, foot-and-mouth disease, bovine spongiform encephalopathy, metabolic disorders caused by toxins found on the feed, and threshold levels of minerals and metabolites. Many, but not all, of the above require an immune response as part of the fight against an external challenge, and measurements have been made of general immune response as a way of describing or predicting how an animal will respond. There are now some examples of industry or breed societies applying selection for resistance to one or more diseases as part of a complete breeding objective in dairy cattle, beef cattle or dual purpose livestock. In most cases, industry and breed societies are in the early stages of applying effective selection pressure for resistance to specific cattle diseases, with the notable exceptions of Scandinavian cattle schemes, which lead the world in this respect.

Genetic parameters for functional traits in dairy cattle from daily random regression models

The objective of the research was to estimate genetic parameters, such as heritabilities and genetic correlations, using daily test day data for milk yield (MY), milking speed (MS), dry matter intake (DMI), and body weight (BW) using random regression methodology. Data were from first lactation dairy cows (n = 320) from the Chamau research farm of the Swiss Federal Institute of Technology, Switzerland over the period from April 1994 to 2004. All traits were recorded daily using automated machines. Estimated heritabilities (h(2)) varied from 0.18 to 0.30 (mean h(2) = 0.24) for MY, 0.003 to 0.098 (mean h(2) = 0.03) for MS, 0.22 to 0.53 (mean h(2) = 0.43) for BW, and 0.12 to 0.34 (mean h(2) = 0.23) for DMI. A permanent environmental effect was included in both the univariate and bivariate models, but was assumed constant in estimating some genetic correlations because of convergence problems. Estimated genetic correlations varied from 0.31 to 0.41 between MY and MS, from -0.47 to 0.29 between MY and DMI, from -0.60 to 0.54 between MY and BW, from 0.17 to 0.26 between MS and DMI, from -0.18 to 0.25 between MS and BW, and from -0.89 to 0.29 between DMI and BW. Genetic correlations for MY, MS, DMI, and BW from calving to midlactation decreased similarly to 0.40, 0.36, 0.14, and 0.36 and, at the end of the lactation, decreased to -0.06, 0.23, -0.07, and 0.09, respectively. Daily genetic variance-covariance of many functional traits are reported for the first time and will be useful when constructing selection indexes for more than one trait based on longitudinal genetic parameters.

Genetic parameters for level and change of body condition score and body weight in dairy cows

(Co)variance components for body condition score (BCS), body weight (BW), BCS change, BW change, and milk yield traits were estimated. The data analyzed included 6646 multiparous Holstein-Friesian cows with records for BCS, BW, and(or) milk yield at different stages of lactation from 74 dairy herds throughout Southern Ireland. Heritability estimates for BCS ranged from 0.27 to 0.37, while those for BCS change ranged from 0.02 to 0.10. Heritability estimates for BW records varied from 0.39 to 0.50, while heritabilities for BW change were similar to those observed for BCS change (0.03 to 0.09). The genetic correlations between BCS and BW at the same days in milk deviated little from 0.50, and the genetic correlations between BCS change and BW change over the same period ranged from 0.42 to 0.55. BCS and BW directly postpartum were both phenotypically and genetically negatively correlated with both BW change and BCS change in early lactation. The genetic correlations between BCS and milk yield were negative. The results of the present study show that animals that lose most BCS in early lactation tend to gain most BCS in late lactation, a trend also exhibited by BW.

Selection for economic efficiency of dairy cattle using information on live weight and feed intake: a review

The objective of this study was to review some of the latest evidence of genetic variation in feed intake and feed utilization and to determine how this variation might be used. The most important sources of genetic variation in gross efficiency are likely to be the quantities of feed eaten and used for yield or maintenance and the extent to which body tissue is mobilized. Accounting for just one of these components when selection is for improved feed efficiency might result in undesirable genetic changes. For example, in an ad libitum feeding system, the heritability of body condition score is reported to be 0.43 for heifers; genetic correlations of body condition score with milk production and live weight were -0.46 and 0.66, respectively. Also, the genetic correlation between milk yield and live weight depends on lactation stage. For example, over the first 26 wk of lactation, this correlation was reported to be -0.09, but, after genetic adjustment for body condition score, the correlation was 0.29. When economic values are being derived, energy norms or genetic correlations can be used, and double counting of the feed costs needs to be avoided. An index that contained linear type traits, however, gave high accuracy of selection. Hence, although there appears to be great potential to improve economic efficiency by selecting for feed intake and live weight or by possible indicator traits, there is still uncertainty about some of the genetic parameters, especially among traits related to health, reproduction, and energy balance.

Genetic parameters for common health disorders of Holstein cows

Observations on 7416 Canadian Holstein cows were examined to estimate genetic parameters for the most common diseases of dairy cows. Mastitis, ovarian cyst, ketosis, milk fever, abomasal displacement, and culling that is due to reproductive failure or leg problems were analyzed as binomial traits, assuming an underlying threshold model that included fixed and random effects. Sire and residual components of variance were estimated by REML to provide heritability estimates from paternal half-sibs. A multiple-trait mixed model was also used to estimate genetic and environmental correlations between production and disease traits. Heritabilities of disease traits were relatively low and ranged from 0 to .15, except for displaced abomasum (h2 = .28). Evidence of genetic antagonism existed between incidence of mastitis and milk production. Incidence of milk fever was genetically associated with cows of lower genetic potential for production. Genetic associations between displaced abomasum and production traits were small, and estimates of genetic correlations between ovarian cyst and milk production were inconsistent across lactations. Ketosis was antagonistically associated genetically with production of milk and fat but was favorably associated with production of protein. The long-term cumulative effect of genetic selection against diseases might be useful to diminish their incidence.

Etiology of acetonemia in Norwegian cattle. 1. Effect of ketogenic silage, season, energy level, and genetic factors

Plasma acetoacetate concentration in the 1st mo of lactation and its relation to BW change, milk yield, DMI, and BW postpartum were studied in 361 first lactation cows during 6 yr. The cows were fed concentrate at 6 and 3 kg/d. Calvings took place from August to December. Single observations for all cows were fitted by a multitrait animal model that accounted for all genetic relationships. Heritability for acetoacetate was .11 with a genetic correlation of .87 for milk yield, -.65 for weight change, and -.13 for BW postpartum. Acetoacetate was higher at 3 kg/d of concentrate than at 6 kg/d, and calving after 3 to 4 mo of indoor feeding was related to higher acetoacetate than was calving shortly after the pasture season. Acetoacetate was related to weight loss postpartum, but at a different degree in different years. In some years, compounds of the silage caused strongly elevated plasma concentrations of acetoacetate after feeding. Experiments were performed to compare hay with silages of different qualities. Rumen concentration of different amines 3 h postfeeding was taken as an index of the amine load of the cow. The concentration of several amines in rumen fluid were high after feeding ketogenic silage.