Association of automatic milking systems milking frequency in primiparous and multiparous cows with their yield and milkability

The aim of the study was to determine the association of automatic milking systems milking frequency (≤2.40, 2.41–2.80 and >2.80 times/day) in primiparous and multiparous cows with their daily milk yield and milkability. The analysis included of the milk production level and the interaction between milking frequency per day and daily milk yield. Regardless of the daily production level, most primiparous cows were milked 2.41–2.80 times/day and most multiparous cows >2.80 times/day. Higher daily milk yield and a more favourable effect of increasing milking frequency on this parameter were observed in multiparous cows, with an increase from 29.7?kg (milking frequency ≤2.40 times/day) to 31.1?kg milk (>2.80 times/day). In primiparous cows, this increase was smaller and amounted to 0.8?kg milk (from 29.2 to 30.0?kg).     

Once-daily milking of Holstein cows for one-week decreases milk yield by twenty-five percent without any carry-over effect

Short-term (i.e. several days) once-daily milking (ODM) of dairy cows could help to improve work organization or quality of life for dairy farmers. ODM implemented during three periods of one week in the descending phase of lactation led to an average 23.4% decrease in the milk yield of 9 Holstein cows compared to 9 other cows on twice-daily milking (TDM). Short-term ODM significantly increased fat content (by 4.5 g/kg on average) and somatic cell count (by 73,000 cells/mL) and decreased lactose content by 1.9 g/kg. Protein content increased (by 2.1 g/kg) only in the third period. When twice-daily milking was resumed, there were no longer between-group differences in daily yields of milk, fat, protein, and somatic cells.     

The effects of feeding frequency on waiting time,milking frequency,cubicle and feeding fence utilization for cows in an automatic milking system

Abstract

In this trial, the effects of the forage feeding frequency on the waiting time prior to milking and the cowshed facility utilization by cows milked in an automatic milking unit (AMU) were studied. The feeding frequency was increased from two times per day to six times per day. It was found that the average waiting time per visit for cows using the AMU was reduced from 755 s to 351 s when the feeding frequency was increased. The daily number of visits (milking visit, failed milking visit and not qualified visit) to the AMU was not affected by the change in feeding frequency. It was also found that increasing the feeding frequency had a positive effect on utilization of the cowshed facilities, such as the occupation of the feeding fence, and on the cowshed facilities in the waiting area (cubicles) of the AMU.     

Estimates of (co)variance components and genetic parameters for body weights and first greasy fleece weight in Malpura sheep

Estimates of (co)variance components and genetic parameters were calculated for birth weight (BWT), weaning weight (WWT), 6 month weight (6WT), 9 month weight (9WT), 12 month weight (12WT) and greasy fleece weight at first clip (GFW) for Malpura sheep. Data were collected over a period of 23 years (1985–2007) for economic traits of Malpura sheep maintained at the Central Sheep & Wool Research Institute, Avikanagar, Rajasthan, India. Analyses were carried out by restricted maximum likelihood procedures (REML), fitting six animal models with various combinations of direct and maternal effects. Direct heritability estimates for BWT, WWT, 6WT, 9WT, 12WT and GFW from the best model (maternal permanent environmental effect in addition to direct additive effect) were 0.19 ± 0.04, 0.18 ± 0.04, 0.27, 0.15 ± 0.04, 0.11 ± 0.04 and 0.30 ± 0.00, respectively. Maternal effects declined as the age of the animal increased. Maternal permanent environmental effects contributed 20% of the total phenotypic variation for BWT, 5% for WWT and 4% for GFW. A moderate rate of genetic progress seems possible in Malpura sheep flock for body weight traits and fleece weight by mass selection. Direct genetic correlations between body weight traits were positive and ranged from 0.40 between BWT and 6WT to 0.96 between 9WT and 12WT. Genetic correlations of GFW with body weights were 0.06, 0.49, 0.41, 0.19 and 0.15 from birth to 12WT. The moderately positive genetic correlation between 6WT and GFW suggests that genetic gain in the first greasy fleece weight will occur if selection is carried out for higher 6WT.     

Forecasting the milk yield of cows on farms equipped with automatic milking system with the use of decision trees

The purpose of this paper was to utilize the decision trees technique to determine the factors responsible for high monthly milk yield in Polish Holstein‐Friesian cows from 27 herds equipped with milking robots. The applied statistical method—the decision tree technique—showed that the most important factors responsible for monthly milk yield of dairy cows using robots were, in descending order of importance: milking frequency, lactation number, month of milking, and type of lying stall. At the same time, it has been ascertained that the highest monthly milk yield (47.24 kg) can be expected from multiparous cows kept in barns with a deep bedding that were milked more frequently than three times per day. On the other hand, the lowest milk production (13.56 kg) was observed among dairy cows milked less frequently than two times a day, with an average number of milked quarters lower than 3.97. The application of the decision trees technique allows a breeder to select appropriate levels of environmental factors and parameters that will help to ensure maximized milk production.     

Estimation of daily and total lactation milk yield of Chios ewes from single morning or evening records

Linear models were developed and evaluated for the estimation of daily (24 h) and total lactation milk yield of dairy sheep from single morning (am) or evening (pm) milking records. A total of 22,908 individual test-day milk records of 5110 ewes of the Chios breed, raised in 46 flocks, were used. Depending on the model, different daily milk yield estimates were derived for each ewe, accounting for lactation number, stage of lactation, season of previous lambing and interval between successive milkings. Daily milk yield was also estimated from doubling the single am or pm record. Actual and estimated yields were compared using root mean square errors (RMSEs), mean absolute differences, an accuracy parameter defined as the ratio of the actual yield variance over the sum of the variances of actual yield and absolute difference, and the product moment correlation between estimated and actual yield. Results were validated on independent datasets. Linear models resulted in less biased and more accurate estimates of the daily milk yield than simply doubling the am or pm record. Root mean square errors decreased by 7-37% and the mean absolute difference was reduced by 1-4% of the average daily yield. Higher accuracy and correlation were obtained from linear model application than doubling. Total lactation milk yield was predicted based on actual daily yield and compared to predictions based on estimated daily yield from am or pm records, as well as directly on single milking records. Root mean square errors obtained when daily yield had been estimated with linear models were 26-35% lower compared to doubling the am or pm yield and 0-13% lower compared to estimating the total lactation yield directly from single milking records. Linear model application also resulted in lower mean absolute difference and higher accuracy and correlation than doubling the am or pm record. Recording the yield of a single milking (am or pm) instead of both can benefit milk recording by reducing its cost and increasing farmer participation. In this context, linear models developed in the present study can be used for the accurate estimation of daily (24 h) and total lactation milk yield from single milking records.     

Estimates of genetic parameters for growth traits in Kermani sheep

Birth weight (BW), weaning weight (WW), 6-month weight (W6), 9-month weight (W9) and yearling weight (YW) of Kermani lambs were used to estimate genetic parameters. The data were collected from Shahrbabak Sheep Breeding Research Station in Iran during the period of 1993-1998. The fixed effects in the model were lambing year, sex, type of birth and age of dam. Number of days between birth date and the date of obtaining measurement of each record was used as a covariate. Estimates of (co)variance components and genetic parameters were obtained by restricted maximum likelihood, using single and two-trait animal models. Based on the most appropriate fitted model, direct and maternal heritabilities of BW, WW, W6, W9 and YW were estimated to be 0.10 +/- 0.06 and 0.27 +/- 0.04, 0.22 +/- 0.09 and 0.19 +/- 0.05, 0.09 +/- 0.06 and 0.25 +/- 0.04, 0.13 +/- 0.08 and 0.18 +/- 0.05, and 0.14 +/- 0.08 and 0.14 +/- 0.06 respectively. Direct and maternal genetic correlations between the lamb weights varied between 0.66 and 0.99, and 0.11 and 0.99. The results showed that the maternal influence on lamb weights decreased with age at measurement. Ignoring maternal effects in the model caused overestimation of direct heritability. Maternal effects are significant sources of variation for growth traits and ignoring maternal effects in the model would cause inaccurate genetic evaluation of lambs.     

Genetic parameters and evaluation of the Tunisian dairy cattle population for milk yield by Bayesian and BLUP analyses

A Markov Chain Monte Carlo Bayesian method and BLUP analyses were used on Tunisian dairy cattle data. Data included 92,106 lactation records collected on 37,536 animals over 19 freshening years, from 1983 to 2001. Each record was partitioned into the fixed effects of herd-year, month of calving, and age-parity, a permanent environmental effect, an additive genetic effect, and a residual effect.

Posterior conditional distributions were determined for variance components and model effects. Solutions (BLUE) and posterior means for levels of herd-year, month of calving, and age-parity showed similar patterns. Posterior means of heritability and repeatability were 0.17 ± 18 × 10^− 5 and 0.39 ± 8 × 10^− 5, respectively. Posterior means of bull's breeding values were compared to bull's BLUP solutions. BLUP solutions were obtained using 0.17 and 0.39, estimated from the data, and 0.25 and 0.40 estimates for heritability and repeatability, respectively. Rank correlations between bull's posterior means and BLUP breeding values were 0.998 and 0.994 using genetic parameters estimated from the data and from the literature, respectively. This correlation coefficient was 0.995 between bull's BLUP solutions using either of the two sets of genetic parameters.     

中国荷斯坦牛头胎产奶量和乳成分遗传参数估计

本研究旨在应用随机回归测定日模型对奶牛生产性状进行遗传评估。收集河南省内17个牧场2008年1月2017年5月共16 335头奶牛头胎174 634条生产性能记录,建立筛选标准对数据进行质控。遗传评估采用随机回归模型,场-测定日为固定效应,以固定回归拟合产犊月龄效应,随机效应包括加性遗传和永久环境效应。固定和随机回归均采用4阶Legendre多项式。结果表明:中国荷斯坦牛头胎测定日产奶量、乳脂率、乳蛋白率、体细胞评分总遗传力分别为0.144 1、0.289 1、0.373 2和0.089 8。本研究为区域性中国荷斯坦牛的遗传评估平台建设和育种规划制定奠定基础。     

The association between fetching for milking and dairy cows'' behaviour at milking, and avoidance of human approach — An on-farm study in herds with automatic milking systems

The present study explores the welfare aspects of involuntary milking in dairy herds with an automatic milking system (AMS) as it focuses on whether fetching of cows for milking may be related to fear/discomfort of the automatic milking unit (AMU) or the milking itself and further, may strain the human–animal relationship. Behavioural data on cow reluctance when entering the AMU, stepping and kicking behaviour during milking and avoidance of humans was collected at 6 two-day visits to 8 Danish commercial AMS herds during a year. The data set for the analysis included one observation per cow of reluctance when entering the AMU and behaviour during milking of a total of 869 cows; 255 cows fetched for milking and 614 non-fetched cows. For 82 of the cows fetched for milking and for 370 of the non-fetched cows the data further included one observation per cow of avoidance towards an approaching unfamiliar human in a test situation. Multivariate analyses by conditional hierarchical log-linear models showed that fetchings were more frequent the first 14 days of lactation (P < 0.001). The multivariate analysis showed no associations between fetching and reluctance at entering the AMU, nor an association to stepping and kicking during milking. However, compared to non-fetched cows, fetched cows were more frequently avoiding the test person in the human approach test (P < 0.001). It is concluded that fetching may strain the human–animal relationship.     

Estimates of genetic parameters for conformation measures and scores in Finnhorse and Standardbred foals

The aim of this study was to estimate genetic parameters for conformation measures and scores in the Finnhorse and the Standardbred foals presented in foal shows. Studied traits included height at withers and at croup, six subjectively evaluated conformation traits and overall grade. Data were from 10‐year period (1995–2004) and consisted of 5821 Finnhorse foals (1–3 years old) with 7644 records and 2570 Standardbred foals (1–2 years old) with 2864 records. Variance components were estimated with REML – animal model using VCE4 program. The model included age class, year of judging, sex and region as fixed effects, and additive genetic, permanent environmental and residual as random effects. Estimates of heritability for measured traits were very high in both breeds (0.88–0.90). Estimates of heritability for conformation traits varied from 0.13 to 0.32 in the Finnhorse and from 0.06 to 0.47 in the Standardbred. In both breeds, estimates of heritability were lowest for hooves and movements at walk, and highest for type and body conformation among scored traits. Estimate of heritability for overall grade was in the Finnhorse 0.32 and in the Standardbred 0.34. Genetic correlations between overall grade and different conformation traits were 0.35–0.84 in the Finnhorse and 0.31–0.88 in the Standardbred. Thus, selection based on the overall grade would improve all studied characteristics.     

Estimation of genetic parameters and genome scan for 15 semen characteristics traits of Holstein bulls

A QTL detection experiment was performed in French dairy cattle to search for QTL related to male fertility. Ten families, involving a total of 515 bulls, were phenotyped for ejaculated volume and sperm concentration, number of spermatozoa, motility, velocity, percentage of motile spermatozoa after thawing and abnormal spermatozoa. A set of 148 microsatellite markers were used to realize a genome scan. First, genetic parameters were estimated for all traits. Semen production traits were found to have moderate heritabilities (from 0.15 to 0.30) while some of the semen quality traits such as motility had high heritabilities (close to 0.60). Genetic correlations among traits showed negative relationships between volume and concentration and between volume and most quality traits such as motility or abnormal sperm while correlations between concentration and these traits were rather favourable. Percentages of abnormal sperm were negatively related to quality traits, especially with motility and velocity of spermatozoa. Three QTL related to abnormal sperm frequencies were significant at p < 0.01. In total, 11 QTL (p < 0.05) were detected. However, the number of QTL detected was within the range of expected false positives. Because of the lack of power to find QTL in this design further analyses are required to confirm these QTL.     

Linear model vs. survival analysis for genetic evaluation of sires for longevity in Chianina beef cattle

The objective of this study was to compare sire EBVs for longevity in Chianina beef cattle estimated with linear models and survival analysis. Two datasets were created, one considered all data (SURVall), the other only uncensored records (SURVun). The linear models were used to analyze longevity measured as three correlated dichotomous (yes/no) measures of survival in the first three parities (LIN-S3) and as an overall measure of lifespan in months (LIN-LPL). Correlation between sire EBVs from the two survival analyses were 0.85. For LIN-S3 the correlations of EBVs across parities were between 0.69 to 0.93. Medium correlations (from 0.50 to 0.62) were found when only uncensored data (SURVun) were compared to the linear model (LIN-S3). Higher correlations (from 0.71 to 0.93) were found when EBV based on both censored and uncensored data (SURVall) were compared to LIN-S3. Heritability was estimated at 0.11, 0.09 and 0.08 for SURVall, SURVun and LIN-LPL, respectively; and 0.05, 0.02 and 0.02, respectively, for survival in the first three parities according to LIN-S3. Linear and non-linear models differed in many aspects; the most precise EBV were obtained when all data was used in the evaluation.     

Genetic and phenotypic parameters of milk yield, milk composition and age at first kidding in Saanen goats from Mexico

A total of 4007 lactation records from 1520 Saanen goats kidding from 1999 to 2006 and obtained from 10 herds in Guanajuato, Mexico, were analyzed to estimate the heritabilities, repeatabilities, as well as genetic, environmental and phenotypic correlations for milk yield (MILK), fat yield (FAT), protein yield (PROT), fat content (%FAT), protein content (%PROT) and age at fist kidding (AFK). A five-trait repeatability model was used to estimate (co)variances for milk traits, and a four-trait animal model for first lactation records was used to estimate (co)variances involving AFK. For MILK, FAT, PROT, %FAT, %PROT and AFK, heritability estimates were 0.17 ± 0.04, 0.19 ± 0.05, 0.17 ± 0.04, 0.32 ± 0.06, 0.38 ± 0.07 and 0.31 ± 0.09, respectively. Repeatabilities for MILK, FAT, PROT, %FAT and %PROT were 0.43 ± 0.02, 0.42 ± 0.02, 0.42 ±0.02, 0.64 ± 0.02, and 0.63 ± 0.02, respectively. The genetic correlations between MILK and FAT, and between MILK and PROT, were high and positive (0.72 ± 0.08 and 0.87 ± 0.04, respectively). Genetic correlations between MILK and %FAT, between MILK and %PROT and between MILK and AFK, were − 0.24 ± 0.16, − 0.30 ± 0.15 and − 0.18 ± 0.23, respectively. Genetic correlations between AFK and FAT and between AFK and PROT were − 0.09 ± 0.24 and − 0.17 ± 0.25, respectively; and genetic correlations between AFK and %FAT and between AFK and %PROT were 0.29 ± 0.35 and 0.14 ± 0.27, respectively. Selection for milk traits is possible using a repeatability animal model. Selection for milk production traits would probably not increase AFK, but more precise estimates of the genetic correlations are required. Selection to lower AFK is possible. These (co)variance estimates would make it possible to predict the selection responses from different economic indices in order to maximize the economic responses for the local markets.     

Estimates of genetic parameters for chemical traits of meat quality in Japanese black cattle

Genetic parameters for 54 carcass and chemical traits, such as general composition (moisture, crude fat and crude protein), fatty acid composition and water‐soluble compounds (free amino acids, peptides, nucleotides and sugars) of 587 commercial Japanese Black cattle were assessed. Heritability estimates for carcass traits and general composition ranged between 0.19–0.28, whereas those for fatty acid composition ranged between 0.11–0.85. Most heritability estimates for water‐soluble compounds were lower than 0.30; these traits were affected by aging period. Moderate heritability was observed for glutamine, alanine, taurine, anserine, inosine 5′‐monophosphate (IMP), inosine and myo‐inositol. In particular, heritability estimates were the highest (0.66) for taurine. Traits with moderate heritability were unaffected by aging period, with the exception of IMP, which was affected by aging period but exhibited moderate heritability (0.47). Although phenotypic correlations of water‐soluble compounds with carcass weight (CW), beef marbling standard (BMS) and monounsaturated fatty acid were generally low, genetic correlations between these traits were low to high. At the genetic level, most of the water‐soluble compounds were positively correlated with monounsaturated fatty acid but negatively correlated with CW and BMS. Thus, our results indicate that genetic variance and correlations could exist and be captured for some of the water‐soluble compounds.     

Estimates of non-genetic effects and genetic parameters for body measures and subjectively scored traits in Finnhorse trotters

This study examined non-genetic effects and genetic parameters of body measures and subjectively scored traits in the Finnhorse trotter population. The data was based on studbook inspections from 1971 to 2004 covering observations on 6381 horses. There were five body measures – height at withers, height at croup, circumference of girth, length of body and circumference of cannon bone – and six subjectively scored traits – character, body conformation, leg stances, quality of legs, hooves and movements – included in the analyses. Multivariate mixed models were applied with year–sex and age as fixed effects and animal as a random effect. The year–sex effect had a significant influence on body measures and scored traits. Age at judging had a significant influence on all traits but height at withers and body conformation. Heritability estimates were from 0.53 to 0.78 for body measures and 0.10 to 0.19 for scored traits. Genetic correlations between body measures were highly positive, from 0.75 to 0.98, whilst genetic correlations between scored traits varied between − 0.20 and 0.51. Genetic correlations between body measures and scored traits were mainly negative, from − 0.38 to 0.09. Our results indicate that additive genetic effects are relevant determinants for body measures of Finnhorse trotters. The scored traits were of low to moderate heritability and were relevantly influenced by environmental effects.     

Cluster and meta‐analyses of genetic parameters for feed intake traits in growing beef cattle

A data set based on 50 studies including feed intake and utilization traits was used to perform a meta‐analysis to obtain pooled estimates using the variance between studies of genetic parameters for average daily gain (ADG); residual feed intake (RFI); metabolic body weight (MBW); feed conversion ratio (FCR); and daily dry matter intake (DMI) in beef cattle. The total data set included 128 heritability and 122 genetic correlation estimates published in the literature from 1961 to 2012. The meta‐analysis was performed using a random effects model where the restricted maximum likelihood estimator was used to evaluate variances among clusters. Also, a meta‐analysis using the method of cluster analysis was used to group the heritability estimates. Two clusters were obtained for each trait by different variables. It was observed, for all traits, that the heterogeneity of variance was significant between clusters and studies for genetic correlation estimates. The pooled estimates, adding the variance between clusters, for direct heritability estimates for ADG, DMI, RFI, MBW and FCR were 0.32 ± 0.04, 0.39 ± 0.03, 0.31 ± 0.02, 0.31 ± 0.03 and 0.26 ± 0.03, respectively. Pooled genetic correlation estimates ranged from ?0.15 to 0.67 among ADG, DMI, RFI, MBW and FCR. These pooled estimates of genetic parameters could be used to solve genetic prediction equations in populations where data is insufficient for variance component estimation. Cluster analysis is recommended as a statistical procedure to combine results from different studies to account for heterogeneity.     

Estimation of genetic parameters of feed intake and daily gain in Durocs using data from electronic swine feeders

Genetic parameters for daily feed intake (DFI, g/day) and daily gain (DG, g/day) were estimated using records of 1916 Duroc boars from electronic feeder stations. Management was limited and resulted in varied ranges of age and weight on test. Boars were housed in 102 pens, each equipped with one feeder, and allowed ad libitum feeding. Weekly averages of DFI and DG were used due to large variation in daily records. Six traits were defined as DFI and DG during 85–106 (period 1), 107–128 (period 2) and 129–150 days of age (period 3). A six‐trait model included age as a linear and a quadratic covariate for DFI and a linear covariate for DG with a fixed effect of year–week–pen and random effects of litter, additive genetic animal and permanent environmental animal. Variance components were estimated by a Bayesian approach using Gibbs sampling algorithm. Estimates of heritability for respective periods were 18%, 12% and 10% for DFI and 21%, 11% and 10% for DG. Genetic correlations between DFI and DG in the same period were 0.70, 0.73 and 0.32 for the respective periods. DFI and DG obtained from automatic feeders can be analysed to reveal variation across testing periods by using weekly averages when many monthly averages are incomplete.     

Estimates of genetic parameters associated with lactation feed intake and reproductive performance in purebred and F1 sows

Daily feed intake during lactation was recorded in parity records from purebred Yorkshire (n = 1587), Landrace (n = 2197) and reciprocal cross F1 (n = 6932) females, and lactation feed intake (LFI) curves were predicted using a mixed model. Evaluation of the difference in feed intake between two consecutive days of lactation resulted in the following classifications: three periods for purebreds, days 1–6, days 7–10 and days 11–18, and two periods for F1 sows, days 1–5 and days 6–18. Average rate of change in intake (ARC), average daily intake (ADI) and variation from predicted LFI values (VAR) were computed for each period of lactation. Gibbs sampling was used to estimate genetic (co)variance components for LFI metrics and reproductive performance traits. Genetic variance estimates for each LFI metric were obtained with univariate animal models, and covariance estimates were estimated with bivariate models. Heritability estimates for ADI, ARC and VAR metrics computed over the duration of lactation were 0.37, 0.24, and 0.16, respectively. Heritability estimates were highly variable across periods of lactation for ARC (0.03–0.17), ADI (0.09–0.36) and VAR (0.04–0.18) metrics in purebred and F1 populations. Genetic correlations between LFI metrics and reproductive traits were relatively low, although LFI metrics later in lactation were more highly correlated with reproductive performance.     

Comparison of selection criteria for milk yield traits of Valle del Belice dairy sheep

The objectives of this work were to investigate alternative selection criteria for milk yield traits in the Valle del Belice sheep breed, which are either corrected for lactation length or not affected by lactation length, to estimate genetic parameters for these alternative selection criteria and to compare the estimated breeding values. The genetic correlations show that corrected milk yield (CMY), maximum test-day yield (MTY) and milk yield at hundred days (MYH), are moderately or weakly correlated with lactation length (LL) (r_g = 0.58, 0.16 and 0.39, respectively). Higher genetic correlation was found between total milk yield (TMY) and LL (r_g = 0.73). Rank correlations between selection criteria for estimated breeding values for the entire data set were above 0.90 for CMY vs. TMY and CMY vs. MYH and were similar for rams and ewes. Very low were the rank correlations for LL vs. MTY and LL vs. MYH in comparison with 0.75 for LL vs. TMY. Under high selection intensity, rank correlations between breeding values from CMY vs. TMY, CMY vs. MYH and MTY vs. MYH were lower, ranging from 0.53 to 0.75, but higher than all other contrasts between selection criteria. The general results obtained in this study show that MYH is a selection criterion that could improve the genetic evaluation in the Valle del Belice dairy sheep.