Linear Type Traits Research Articles

Short communication: Genetic relationships of milk coagulation properties with body condition score and linear type traits in Holstein-Friesian cows

Milk coagulation properties (MCP) are gaining popularity among dairy cattle producers and the improvement of traits associated with MCP is expected to result in a benefit for the dairy industry, especially in countries with a long tradition in cheese production. The objectives of this study were to estimate genetic correlations of MCP with body condition score (BCS) and type traits using data from first-parity Italian Holstein-Friesian cattle. The data analyzed consisted of 18,460 MCP records from 4,036 cows with information on both BCS and conformation traits. The cows were daughters of 246 sires and the pedigree file included a total of 37,559 animals. Genetic relationships of MCP with BCS and type traits were estimated using bivariate animal models. The model for MCP included fixed effects of stage of lactation, and random effects of herd-test-date, cow permanent environment, additive genetic animal, and residual. Fixed factors considered in the model for BCS and type traits were herd-date of evaluation and interaction between age at scoring and stage of lactation of the cow, and random terms were additive genetic animal, cow permanent environment, and residual. Genetic relationships between MCP and BCS, and MCP and type traits were generally low and significant only in a few cases, suggesting that MCP can be selected for without detrimental effects on BCS and linear type traits.

Establishment of optimum regression model and determination of relationships between body measurements and slaughter traits in Japanese quails by path analysis

Path analysis was used to investigate direct, indirect and total effects of some morphological measurements on slaughter and carcass traits in Japanese quails. Bodyweight, shank length, shank diameter, breast circumference and body length measurements were taken from 219 Japanese quails. Bivariate correlations between carcass weight and morphological traits in quails ranged from 0.405 to 0.864. The direct effect of bodyweight on carcass weight was the strongest in the study and (path coefficient of 0.85) positively influenced carcass weight (P < 0.01). The direct effect of other linear-type traits on carcass weight was non-significant as revealed by t-test (P > 0.05). These traits were indirectly realised mostly by shank diameter. Thus, they were dropped from the final regression equations to obtain much more simplified prediction models. The optimum multiple regression equation for Japanese quails included bodyweight, with coefficient of determination (R2) of 0.7463. The correlation between characters was determined in more detail by using path analysis in this study. Thus, it was shown that path analysis could be used for selecting a variable. The forecast indices obtained in this study could aid in weight estimation, selection and breeding programs.

Factor analysis of linear type traits and their relation with longevity in brazilian holstein cattle.

In this study we aimed to evaluate the reduction in dimensionality of 20 linear type traits and more final score in 14,943 Holstein cows in Brazil using factor analysis, and indicate their relationship with longevity and 305 d first lactation milk production. Low partial correlations (−0.19 to 0.38), the medium to high Kaiser sampling mean (0.79) and the significance of the Bartlett sphericity test (p<0.001), indicated correlations between type traits and the suitability of these data for a factor analysis, after the elimination of seven traits. Two factors had autovalues greater than one. The first included width and height of posterior udder, udder texture, udder cleft, loin strength, bone quality and final score. The second included stature, top line, chest width, body depth, fore udder attachment, angularity and final score. The linear regression of the factors on several measures of longevity and 305 d milk production showed that selection considering only the first factor should lead to improvements in longevity and 305 milk production.

Prolificacy and Its Relationship with Age, Body Weight, Parity, Previous Litter Size and Body Linear Type Traits in Meat-type Goats.

Data on age and body weight at breeding, parity, previous litter size, days open and some descriptive body linear traits from 389 meat-type, prolific Black Bengal goats in Tripura State of India, were collected for 3 and 1/2 years (2007 to 2010) and analyzed using logistic regression model. The objectives of the study were i) to evaluate the effect of age and body weight at breeding, parity, previous litter size and days open on litter size of does; and ii) to investigate if body linear type traits influenced litter size in meat-type, prolific goats. The incidence of 68.39% multiple births with a prolificacy rate of 175.07% was recorded. Higher age (>2.69 year), higher parity order (>2.31), more body weight at breeding (>20.5 kg) and larger previous litter size (>1.65) showed an increase likelihood of multiple litter size when compared to single litter size. There was a strong, positive relationship between litter size and various body linear type traits like neck length (>22.78 cm), body length (>54.86 cm), withers height (>48.85 cm), croup height (>50.67 cm), distance between tuber coxae bones (>11.38 cm) and distance between tuber ischii bones (>4.56 cm) for discriminating the goats bearing multiple fetuses from those bearing a single fetus.

Random regression test-day model for clinical mastitis: Genetic parameters, model comparison, and correlations with indicator traits

The objective was to study genetic (co)variance components for binary clinical mastitis (CM), test-day protein yield, and udder health indicator traits [test-day somatic cell score (SCS) and type traits of the udder composite] in the course of lactation with random regression models (RRM). The study used a data set from selected 15 large-scale contract herds including 26,651 Holstein cows. Test-day production and CM data were recorded from 2007 to 2012 and comprised parities 1 to 3. A longitudinal CM data structure was generated by assigning CM records to adjacent official test dates. Bivariate threshold-linear RRM were applied to estimate genetic (co)variance components between longitudinal binary CM (0=healthy; 1=diseased) and longitudinal Gaussian distributed protein yield and SCS test-day data. Heritabilities for liability to CM (heritability ~0.15 from 0 to 305 d after calving) were slightly higher than for SCS for corresponding days in milk (DIM) in the course of lactation. Daily genetic correlations between CM and SCS were moderate to high (genetic correlation ~0.70), but substantially decreased at the very end of lactation. Genetic correlations between CM at different test days were close to 1 for adjacent test days, but were close to zero for test days far apart. Daily genetic correlations between CM and protein yield were low to moderate. For identical DIM (e.g., DIM 20, 160, and 300), genetic correlations were −0.03, 0.11, and 0.18, respectively, and disproved pronounced genetic antagonisms between udder health and productivity. Correlations between estimated breeding values (EBV) for CM from the RRM and official EBV for linear type traits of the udder composite, including EBV from 74 influential sires (sires with >60 daughters), were −0.31 for front teat placement, −0.01 for rear teat placement, −0.31 for fore udder attachment, −0.32 for udder depth, and −0.08 for teat length. Estimated breeding values for CM from the RRM were compared with EBV from a multiple-trait model and with EBV from a repeatability model. For test days covering an identical time span and on a lactation level, correlations between EBV from RRM, multiple-trait model, and repeatability model were close to 1. Most relevant results suggest the routine application of threshold RRM to binary CM to (1) allow selection of genetically superior sires for distinct stages of lactation and (2) achieve higher selection response in CM compared with selection strategies based on indicator type traits or based on the indicator-trait SCS.

Genetics of reproductive performance in seasonal calving beef cows and its association with performance traits

Due primarily to a lack of phenotypic data, little research has been undertaken on the genetics of reproductive performance in beef cattle. The objective of this study was to quantify, using data from the Irish national cattle herd, the contribution of additive genetics to phenotypic differences in reproductive performance in beef cattle and to investigate whether routinely available early predictors of genetic merit for reproductive performance exist. Up to 218,718 parity records from 156,506 animals were used to estimate variance components for a range of reproductive traits using repeatability animal linear mixed models. Covariances with performance traits were estimated using bivariate sire linear mixed models. The reproductive traits were age at first calving, calving in the first 42 d of the calving seasons (defined separately in heifers and cows), calving interval between consecutive calving events, and survival to the next lactation. Performance traits included calving dystocia, linear type traits describing the skeletal, muscular, and functional characteristics of an animal, live weight and price, carcass traits, and producer subjectively scored traits of weanling quality and docility. Heritability for age at first calving was 0.31 while the heritability of the remaining reproductive traits ranged from 0.01 to 0.06; repeatability estimates varied from 0.02 to 0.06. Increased muscularity, measured either by trained assessors or producers on live animals, or by mechanical grading machines on slaughtered animals (i.e., carcass conformation), was genetically correlated with reduced reproductive performance for some of the reproductive variables assessed. This is one of the largest studies undertaken on the genetics of reproduction in beef herds and clearly shows that genetic selection for improved reproductive performance in beef herds is feasible. However, breeding goals that select for muscularity and live weight or growth rate should be cognizant of indirect response to selection that may cause any deterioration in reproductive performance.

Genetic Association Between Herd Survival and Linear Type Traits in Holstein Cows Under Tropical Conditions

The objective of this study was to estimate genetic parameters for survival measures from birth to 60 and 72 months of age, as well as survival up to 48 and 54 months after first calving. The genetic association of these measures with 20 linear type traits and final score in Holstein cows, born between years 1990 to 2004, was also evaluated. The components of (co)variance were estimated by Bayesian methods, using the programme THRG1BBS1F 90 in bivariate analyses, considering animal threshold model for measures of survival, and animal linear model for linear type traits. The mean posterior heritability for the measures of survival ranged from 0.09 to 0.15, and for those of the linear type traits ranged from 0.07 to 0.36. The posterior genetic correlation between linear type traits and measures of survival varied from -0.37 to 0.50, respectively. Indirect genetic selection for udder depth, rear teat placement, udder texture, bone quality, fore udder attachment, body depth and chest width may lead to correlated gains in longevity in Holstein cows under tropical conditions.

Appraisal of linear type traits in Sahiwal cattle

To define Sahiwal breed on the basis of linear type traits, 101 purebred Sahiwal cow available at Veterinary college, Durg were used. All the traits were scaled and scored as per the guidelines of International committee for animal recording, (2001). Thus, Sahiwal can be defined as breed of cattle having stature of 128.90 cm, chest width of 26.87 cm, body depth of 64.68 cm, rump angle of 9.59 cm, rump width of 15.40 cm, rear leg set (side view) of 158.740, rear leg set (rear view) of -4.81 cm, foot angle of 48.390, udder depth of 12.39 cm, rear udder height of 12.65 cm, udder balance of 0.54 cm, udder cleft of 1.76 cm, fore udder attachment of 127.380, teat length of 6.92 cm, fore teat placement of 5.34 score, rear teat placement of 6.37 score and teat thickness of 2.78 cm. It is having taller height at rump, narrower teat thickness and rest of the traits being intermediate. The age of an animal had shown to have significant effect on expression of some linear type traits, thus, should always be taken in to consideration while defining animals on the basis of linear type traits.

Evaluation of inbreeding depression in Holstein cattle using whole-genome SNP markers and alternative measures of genomic inbreeding

The effects of increased pedigree inbreeding in dairy cattle populations have been well documented and result in a negative impact on profitability. Recent advances in genotyping technology have allowed researchers to move beyond pedigree analysis and study inbreeding at a molecular level. In this study, 5,853 animals were genotyped for 54,001 single nucleotide polymorphisms (SNP); 2,913 cows had phenotypic records including a single lactation for milk yield (from either lactation 1, 2, 3, or 4), reproductive performance, and linear type conformation. After removing SNP with poor call rates, low minor allele frequencies, and departure from Hardy-Weinberg equilibrium, 33,025 SNP remained for analyses. Three measures of genomic inbreeding were evaluated: percent homozygosity (FPH), inbreeding calculated from runs of homozygosity (FROH), and inbreeding derived from a genomic relationship matrix (FGRM). Average FPH was 60.5±1.1%, average FROH was 3.8±2.1%, and average FGRM was 20.8±2.3%, where animals with larger values for each of the genomic inbreeding indices were considered more inbred. Decreases in total milk yield to 205d postpartum of 53, 20, and 47kg per 1% increase in FPH, FROH, and FGRM, respectively, were observed. Increases in days open per 1% increase in FPH (1.76 d), FROH (1.72 d), and FGRM (1.06 d) were also noted, as well as increases in maternal calving difficulty (0.09, 0.03, and 0.04 on a 5-point scale for FPH, FROH, and FGRM, respectively). Several linear type traits, such as strength (−0.40, −0.11, and −0.19), rear legs rear view (−0.35, −0.16, and −0.14), front teat placement (0.35, 0.25, 0.18), and teat length (−0.24, −0.14, and −0.13) were also affected by increases in FPH, FROH, and FGRM, respectively. Overall, increases in each measure of genomic inbreeding in this study were associated with negative effects on production and reproductive ability in dairy cows.

Short communication: Genetic evaluation of mobility for Brown Swiss dairy cattle

Genetic parameters were estimated for mobility score and 16 linear type traits of Brown Swiss dairy cattle. Mobility is an overall assessment trait that measures a cow's ability to move, as well as the structure of her feet, pasterns, and legs. Scores from 50 to 99 were assigned by appraisers for the Brown Swiss Cattle Breeders’ Association of the USA beginning in June 2007. Only scores made before 69 mo of age were used. After edits, 32,710 records were available for 19,472 cows in 819 herds. The model included fixed effects for the interaction of herd and appraisal date (2,109 groups), appraisal age within parity (46 groups), and lactation stage within parity (21 groups), as well as random effects for animal, permanent environment, and residual error. A multi-trait analysis was conducted using canonical transformation, multiple diagonalization, and a decelerated expectation-maximization REML algorithm. Heritability was estimated to be 0.21 for mobility and ranged from 0.06 to 0.37 for the other 16 type traits. The traits with the highest genetic correlation with mobility were final score (0.78), rear legs (rear view; 0.74), rear udder width (0.52), and foot angle (0.51). Predicted transmitting ability (PTA) for mobility was calculated using the Brown Swiss multi-trait type evaluation system but included only appraisals for which all traits had been scored. For the 1,868 bulls evaluated, PTA for mobility ranged from 1.6 to −1.8 with a standard deviation of 0.5 and was most highly correlated with PTA for final score (0.88), rear legs (rear view; 0.77), rear udder height (0.70), and rear udder width (0.69), as expected from the trait correlations. When matched with official US national evaluations from August 2011, PTA mobility had moderately high correlations with PTA for milk, fat, and protein yields, as well as productive life (0.31–0.41). The mobility trait may provide a more accurate assessment of the structural soundness required for longevity than does the feet-legs composite.

English

Data on some production performance traits of 1000 milch Sahiwal cows from 3451 cows maintained at the Livestock Experiment Station, Bahadurnagar, Okara, Pakistan during the period from 2000 to 2009 were selected to study the relationship between 12 linear type traits and reproductive performance of the Sahiwal cows. The reproductive efficiency (RE) was measured in terms of calving interval from the first five lactations. The type scores were standardized for stage of lactation, age at first calving and scoring. The mean scores of linear type traits (rump width, stature, chest and body, suspensory ligament) varied from 72.6±0.78 to 81.1±0.83 points. The estimates of heritability (h2) for most of these type traits were medium 0.31±0.22 to high 0.82±0.31 and indicated the existence of large additive genetic variability for these traits in this breed. The phenotypic correlations of linear type traits with RE ranged between -0.1.6 ± 0.08 and 0.10 ± 0.09. All the 12 linear type traits accounted for 92.96% of the variability in RE of Sahiwal cows. Step-wise regression analysis revealed that 75% of the variation accounted by all linear type traits in RE could be predicted by a sub-set of four type traits (TT) which included stature, chest and body, pelvic angle and udder depth. It was concluded that in the case of absence of records, the reproductive performance of Sahiwal cows can be predicted at an early age using some linear type traits. Key words: Reproductive efficiency, type traits, heritability.

CELL BIOLOGY SYMPOSIUM: Genetics of feed efficiency in dairy and beef cattle1

Increasing food production for the growing human population off a constraining land base will require greater efficiency of production. Genetic improvement of feed efficiency in cattle, which is cumulative and permanent, is one likely vehicle to achieving efficiency gains. The objective of this review is to summarize genetic parameters for feed efficiency traits in dairy and beef cattle and also to address some of the misconceptions associated with feed efficiency in these sectors, as well as discuss the potential use of feed efficiency in breeding programs. A meta-analysis of up to 39 scientific publications in growing cattle clearly showed that genetic variation in feed efficiency exists with a pooled heritability for residual feed intake (RFI) and feed conversion efficiency of 0.33 ± 0.01 (range of 0.07 to 0.62) and 0.23 ± 0.01 (range of 0.06 to 0.46), respectively. Heritability estimates for feed efficiency in cows were lower; a meta-analysis of up to 11 estimates revealed heritability estimates for gross feed efficiency and RFI of 0.06 ± 0.010 and 0.04 ± 0.008, respectively. Meta-analysis of genetic correlations between feed intake, feed efficiency and other performance traits are presented, and selection index theory is used to calculate the proportion of genetic variation in feed intake that can be explained by easy to measure, and often already collected, data. A large proportion of the genetic variation in feed intake could be explained in both growing animals and lactating animals using up to 5 predictor traits, including BW, growth rate, milk yield, body composition, and linear type traits reflecting body size and muscularity. Knowledge of genetic merit for feed intake can be used, along with estimates of genetic merit for energy sinks, to calculate genetic merit for feed efficiency. Therefore, the marginal benefit of collecting actual feed intake data, using the genetic parameters used in this study, appears to be low. There is now sufficient information available to develop a road map on how best to direct research to ensure long-term food security for a growing human population. Gaps in knowledge are identified here, and possibilities to address these gaps are discussed.

Heritability of linear type traits in the autochthonous Rendena dual purpose breed

The aim of the study was to estimate heritabilities (h2) of type traits and linear description scores in Rendena breed. Five traditional summary traits and 20 linear descriptions were recorded on 9,776 Rendena primiparous cows. All available pedigree information (16,234 animals) was used to set up the relationship matrix among animals. Data were analyzed using a single-trait animal model, accounting for the following effects: herd-year-classifier, days in milk, age at first calving, and the genetic additive cow effect. The most heritable trait was the stature (h2 = 0.53), whereas the lowest value was found for feet (0.13). Other considerable values of heritability were found for body size (0.45), body length (0.40), and udder width (0.43). Medium-high heritability estimates were obtained for fleshiness (0.33), and udder (0.35), and regarding linear description for thigh-buttocks traits (0.32, and 0.33), thinness and rump angle (0.36 for both traits), as well as teat length (0.33). On the other hand suspensory ligament (0.17), and thorax length (0.16) showed low heritability values. However, the general good heritability estimates suggest the possibility to use linear description or type traits in genetic evaluation of Rendena cattle.

국내 Holstein종 젖소의 경제형질과 착유량에 따른 소득의 유전모수 추정

Korean Animal Improvement AssociationABSTRACTThe data including milk yields, fat and protein percent for 628,395 heads collected by National Agricultural Cooperative Federation, 15 type traits and final score for 62,262 heads collected by Korea Animal Improvement Association, which were born in 1998 to 2004, and net profits calculated from milk price and raising expenses of individuals were used to estimate genetic parameters. The highest positive genetic correlation, 0.81, was shown between body depth(BD) and loin strength(SR). Genetic correlations between body depth(BD) and udder depth(UD), front teat placement(TP) and front teat length(TL) were '0.23, which were lowest among the linear type traits. Furthermore, medium level of negative genetic correlations were shown the milk yield with milk contents rate traits. Mostly low level of positive genetic correlations were shown between the milk traits and linear score traits except milk yield and stature. Most of the genetic correlations of between the linear score traits and net profit were low level of positive or negative genetic correlations. Among the genetic correlations, body depth(BD), angularity(DF) and rear attachment width(UW), and final score(FS) with net profit were high as 0.17, 0.17, 0.18 and 0.18, respectively. Finally all of the genetic correlations between net profit and milk traits were positive and higher than the linear traits with positive genetic correlations. The results of this study suggest that net profit has been related with the linear traits, such as body depth(BD), angularity(DF) and rear attachment width(UW) traits, and furthermore, milk traits including yield and contents rates influence positively and greatly on net profit. (Key words :Milk yield traits, Linear type traits, Net profit, Genetic parameter, Genetic parameter)

Relationship between conformation traits and longevity in Polish Holstein Friesian cattle

A Weibull proportional hazard model was applied to examine the impact of conformation on true and functional longevity of Polish HF cattle. Lifetime records of 592,639 cows from 2369 herds calving from 1995 to 2008 were used. Conformation data available for 236,137 cows consisted of phenotypic scores for 14 linear traits. True longevity (LPL) was defined as the number of days from first calving to culling or censoring, and functional longevity (FLPL) as LPL adjusted for production. Linear type traits were added into the reference model, which included random effect of herd–year–season, and fixed effects of age at first calving, year–season, parity-stage of lactation, annual change in herd size, and (for FLPL) fat and protein yield. The strongest and positive influence on true longevity was found for udder traits. Capacity traits, rump traits, teat length and rear leg set displayed intermediate optima with respect to LPL. The highest impacts on functional longevity were from udder depth, body depth, chest width, and dairy character. Those traits can be considered early predictors. In respect to FLPL, udder depth had a positive impact, body depth showed an intermediate optimum, and the influences of chest width and dairy character were negative.

Genetic correlations between longevity and conformation traits in the Czech Holstein population

Genetic correlations between longevity and conformation traits were estimated using data on Czech Holstein cows first calved in the years 1993&amp;ndash;2008. Longevity traits considered were length of productive life and number of lactations initiated and their functional equivalents (i.e. the longevity traits corrected for milk production). Conformation traits were twenty one linear descriptive type traits, six composite traits and height at sacrum measured in cm. A possible nonlinear relationship between conformation and longevity traits was also investigated. The heritabilities ranged from 0.05 to 0.43 for conformation traits and from 0.03 to 0.05 for longevity traits. Low to moderate genetic relationships between conformation and longevity traits were found. The genetic correlations were higher for functional longevity than for direct longevity traits. Negative genetic correlations with all longevity traits were found for height at the sacrum, stature, dairy form, body conformation, and capacity. Final score showed weak genetic correlation with all analyzed longevity traits. Positive genetic correlations occurred between feet and legs and direct longevity and functional longevity (0.19, 0.14) and between udder and direct longevity (0.10). Body condition score and angularity showed strong genetic correlations with functional longevity (body condition score 0.30, angularity &amp;ndash;0.31). Foot and leg traits showed weak genetic correlations with longevity traits except rear legs set (side view) (&amp;ndash;0.24) and hock quality (0.19). The udder traits showed inconsistent and rather weak genetic correlations with longevity traits, with the exception of a stronger genetic correlation between rear udder width and functional longevity (&amp;ndash;0.22) and between central ligament and number of lactations (&amp;ndash;0.18, &amp;ndash;0.19). The teat traits showed always negative genetic correlations with longevity traits. The strongest correlations were found for rear teat position (&amp;ndash;0.28) and the weakest for teat length (&amp;ndash;0.03). Some conformation traits showed markedly stronger genetic correlations with functional longevity than with direct longevity (rear udder width and rear udder height, dairy form, body condition score, angularity, rear legs set (side view), rear legs rear view). A quadratic relationship between conformation and longevity traits did exist. Even if the linear relationship generally prevailed, the quadratic relationship should be taken into account. &amp;nbsp;

Application of multivariate principal component analysis to morphological characterization of indigenous goats in Southern Nigeria

Phenotypic variation present in a population arises due to genotypic and environmental effects, and the magnitude of phenotypic variability differs under different environmental conditions, therefore, the purpose of this study was to objectively describe the linear type traits of extensively managed mature indigenous goats of Southern Nigeria and to predict body weight from their orthogonal shape characters using principal component analysis. Body weight and four body measurements namely, height at withers, neck length, body length and heart girth were measured in 265 randomly selected West African Dwarf (WAD) and Red Sokoto (RS) goats of both sexes. RS goats had significantly (P &lt; 0.05) higher morphological traits compared to their WAD counterparts. Sexual dimorphism was observed in all the traits with higher values recorded for males. Phenotypic correlations among body weight and biometric traits were positive and highly significant (r = 0.76–0.91 versus 0.82–0.97 and 0.66–0.94 versus 0.83–0.91 for WAD and RS female and male goats, respectively). In the varimax rotated principal component factor analysis, two factors were extracted for each sex of the two breeds, although with varying degrees of factor loadings. The principal component based regression models, which are preferable for selecting animals for optimal balance, accounted for 89.00 and 96.00% as well as 81.00 and 91.00% of the variation in body weight of female and male WAD and RS goats, respectively. The information obtained could be useful in designing appropriate management, selection and breeding programmes for utilization of goat genetic resources.

Animal muscularity and size are genetically correlated with animal live-weight and price

Animal price and live-weight contribute substantially to the overall profitability of beef and dairy production systems. However, animal data on price and live-weight are not routinely available on all animals since not all animals are sold or weighed during their lifetime. Previous studies have shown that linear type traits can be useful predictors of profitability. Therefore, the main objective of this study was to quantify the genetic associations between muscular, skeletal and functional linear type traits with both live-weight and price on animals. A total of 132,376 live-weight and animal price records were available, as well as linear type trait data from 35,669 animals aged between 180 and 364days. Phenotypic and genetic (co)variance components for animal price, live-weight and linear type traits, were estimated using linear animal mixed models. In general greater prices were paid for taller, deeper and wider animals as evidenced by the moderate genetic correlations between the skeletal and muscularity type traits and animal price. Live-weight, along with 15 type traits, explained 86% of the genetic variation in price; the 15 linear type traits alone explained 73% of the genetic variation in animal price while four selected type traits explained 49% of the genetic variation. Results from this study show that some linear type traits are strongly genetically correlated with both animal live-weight and price and these can be used to enhance the accuracy of selection for animal price and live-weight especially where such data may be limited.

Genetic parameters for female fertility, locomotion, body condition score, and linear type traits in Czech Holstein cattle

The aim of this study was to estimate genetic parameters for fertility traits and linear type traits in the Czech Holstein dairy cattle population. Phenotypic data regarding 12 linear type traits, measured in first lactation, and 3 fertility traits, measured in each of first and second lactation, were collected from 2005 to 2009 in the progeny testing program of the Czech-Moravian Breeders Corporation. The number of animals for each linear type trait was 59,467, except for locomotion, where 53,436 animals were recorded. The 3-generation pedigree file included 164,125 animals. (Co)variance components were estimated using AI-REML in a series of bivariate analyses, which were implemented via the DMU package. Fertility traits included days from calving to first service (CF1), days open (DO1), and days from first to last service (FL1) in first lactation, and days from calving to first service (CF2), days open (DO2), and days from first to last service (FL2) in second lactation. The number of animals with fertility data varied between traits and ranged from 18,915 to 58,686. All heritability estimates for reproduction traits were low, ranging from 0.02 to 0.04. Heritability estimates for linear type traits ranged from 0.03 for locomotion to 0.39 for stature. Estimated genetic correlations between fertility traits and linear type traits were generally neutral or positive, whereas genetic correlations between body condition score and CF1, DO1, FL1, CF2 and DO2 were mostly negative, with the greatest correlation between BCS and CF2 (−0.51). Genetic correlations with locomotion were greatest for CF1 and CF2 (−0.34 for both). Results of this study show that cows that are genetically extreme for angularity, stature, and body depth tend to perform poorly for fertility traits. At the same time, cows that are genetically predisposed for low body condition score or high locomotion score are generally inferior in fertility.

Production, reproduction, health, and growth traits in backcross Holstein × Jersey cows and their Holstein contemporaries

A total of 648 purebred Holstein and 319 backcross Holstein × Jersey dairy cattle were compared for production, reproduction, health, linear type, and growth traits. Animals were born between 2003 and 2009 and were housed in the University of Wisconsin–Madison Integrated Dairy Facility. All animals had Holstein dams; lactating dams were mated to unproven Holstein sires to produce purebred (control) Holsteins or to unproven F1 Jersey × Holstein crossbred sires to produce backcross animals, whereas nulliparous dams were mated to proven Holstein sires to produce purebred (other) Holsteins. Traits were analyzed using mixed linear models with effects of season of birth, age of dam, sire, birth year of sire, days in milk, lactation, and linear type score evaluator. Control Holsteins had greater 305-d milk yield (12,645 vs. 11,456kg), 305-d mature equivalent milk yield (13,420 vs. 12,180kg), peak daily milk yield (49.5 vs. 46.4kg), total lactation milk yield (11,556 vs. 10,796kg), and daily fat-corrected milk yield (43 vs. 40kg) compared with backcrosses. Days open and services per conception as a heifer or cow did not differ between control Holsteins, other Holsteins, or backcrosses. The proportion of first-parity births that required assistance was less in control Holsteins than in backcross cows (3.7 vs. 11.2%). The incidence of scours or respiratory problems in calves did not differ between control Holsteins, other Holsteins, and backcrosses, nor did the incidence of mastitis, injury, or feet problems. Control Holstein heifers were heavier (629 vs. 557kg), with greater hip height (145 vs. 139cm), body length (167 vs. 163cm), heart girth (205 vs. 198cm), and hip width (54 vs. 53cm) at 22 mo of age. On a 50-point scale for linear type traits, Holsteins were larger in stature compared with backcrosses (41 vs. 28), had wider rumps (37 vs. 33), and wider rear udders (34 vs. 32). Results of this study suggest that backcross Holstein × Jersey cattle have decreased production but fail to demonstrate an advantage in health and reproduction compared with purebred Holsteins.