Standard Milk Yield Research Articles

Detection of putative loci affecting milk yield in Turkish Awassi sheep using microsatellite markers.

On the basis of comparisons between bovine and ovine genome mapping information, the aim of the study was to analyze the genetic diversity of selected DNA microsatellites from the bovine genome and to investigate their correlation with the average daily milk yield in Awassi sheep. 18 informative microsatellite markers were selected from the significant QTL regions affecting milk yield identified in the bovine genome in previous studies. The selected microsatellite markers were then amplified by PCR as reciprocal amplifications on the genomic DNA of Awassi sheep, with standard daily milk yield records. Thus, in this study, 18 microsatellite markers associated with milk yield in the bovine genome were examined for both determination of genetic polymorphism within the flock and the effects of marker loci on average daily milk yield in Awassi sheep. Allele frequencies of markers were determined based on the results of fragment analysis. The analysis of variance showed that the 123bp allele at the marker locus BMS1341 on BTA2 significantly influenced the average daily milk yield of Ivesi sheep (P < 0.01). On the other hand, the BMS381 locus with a 115bp allele on BTA2, the MCM140 locus with a 185bp allele on BTA6, the BMS2721 locus with a 155bp allele, the BM1237 locus with 174 and 180bp alleles on BTA7, and finally, the BMS1967 locus with a 117bp allele, the BM4208 locus with 176 and 182bp alleles, and the INRA locus with a185 bp allele on BTA8 showed moderately significant effects on the average daily milk yield of Ivesi ewes (P < 0.05).

Genetic analysis of first lactation and lifetime performancetraits in composite Vrindavani cattle: important considerations for higher milk production.

The present study was aimed to evaluate the influence ofnon-genetic factors on several first lactation and lifetime performance traits and elucidate their genetic parameters in an organized Vrindavani cattle population.Data on eight first-lactation and thirteen lifetime traits were collected on 2400 cows with pedigree records that werereared during33-year period (1989-2021). The first-lactation traits included age at first calving (AFC), total milk yield (FTMY), standard milk yield (FSMY305), peak yield (FPY), lactation length (FLL), dry period (FDP), service period (FSP) and calving interval (FCI). Whereas, the lifetime traits mainly included total lifetime milk yield (TLMY), total standard milk yield (TSMY), number of lactations completed (NL), total lactation length (TLL), herd life (HL), productive life (PL), average milk yield per day of herd life (TLMY/HL), average milk yield per day of productive life (TLMY/PL), average milk yield per day of productive life (TLMY/TLL). Other lifetime production traits included average service period (ASP), average dry period (ADP), average calving interval (ACI) and unproductive days (UD).The heritability estimates of first-lactation traits ranged between 0.026 and 0.228and were found to be low for AFC (0.180 ± 0.042), FCI (0.191 ± 0.125), FSMY305 (0.145 ± 0.061), FTMY (0.165 ± 0.048), FDP (0.052 ± 0.049) and FSP (0.026 ± 0.033); however, FLL (0.229 ± 0.044) and FPY (0.202 ± 0.046) showed moderate heritability. Positive phenotypic correlation (p < 0.001) was revealed among FTMY, TLMY, TLL, HL and PL. The AFC produced a significant effect (p < 0.05) on several traits i,e, TLL, TLMY/HL, FSMY305, FPY, TLMY, HL and TLMY/PL.Lower AFC was associated with higher TLMY, TLL and TLMY/HL; while FSMY305, FPY, HL and TLMY/PL were higher in heifers that calved late in their life. The results revealed that AFCmay be optimized with first lactation and lifetime traits for this population.

Transcriptome analysis of the Bactrian camel (Camelus bactrianus) reveals candidate genes affecting milk production traits

BackgroundMilk production traits are complex traits with vital economic importance in the camel industry. However, the genetic mechanisms regulating milk production traits in camels remain poorly understood. Therefore, we aimed to identify candidate genes and metabolic pathways that affect milk production traits in Bactrian camels.MethodsWe classified camels (fourth parity) as low- or high-yield, examined pregnant camels using B-mode ultrasonography, observed the microscopic changes in the mammary gland using hematoxylin and eosin (HE) staining, and used RNA sequencing to identify differentially expressed genes (DEGs) and pathways.ResultsThe average standard milk yield over the 300 days during parity was recorded as 470.18 ± 9.75 and 978.34 ± 3.80 kg in low- and high-performance camels, respectively. Nine female Junggar Bactrian camels were subjected to transcriptome sequencing, and 609 and 393 DEGs were identified in the low-yield vs. high-yield (WDL vs. WGH) and pregnancy versus colostrum period (RSQ vs. CRQ) comparison groups, respectively. The DEGs were compared with genes associated with milk production traits in the Animal Quantitative Trait Loci database and in Alashan Bactrian camels, and 65 and 46 overlapping candidate genes were obtained, respectively. Functional enrichment and protein–protein interaction network analyses of the DEGs and candidate genes were conducted. After comparing our results with those of other livestock studies, we identified 16 signaling pathways and 27 core candidate genes associated with maternal parturition, estrogen regulation, initiation of lactation, and milk production traits. The pathways suggest that emerged milk production involves the regulation of multiple complex metabolic and cellular developmental processes in camels. Finally, the RNA sequencing results were validated using quantitative real-time PCR; the 15 selected genes exhibited consistent expression changes.ConclusionsThis study identified DEGs and metabolic pathways affecting maternal parturition and milk production traits. The results provides a theoretical foundation for further research on the molecular mechanism of genes related to milk production traits in camels. Furthermore, these findings will help improve breeding strategies to achieve the desired milk yield in camels.Graphical

Test-day and other milk recording options for prediction of lactation milk yield in Jaffarabadi (Bubalus bubalis) buffaloes

Generally, standard lactation milk yield is predicted based on test-day records collected at monthly intervals. Test-day milk production at different time intervals other than monthly intervals can be used to predict lactation milk yield of field bovines in field conditions. With the same possibility, this study was carried out to predict lactation milk yield in Jaffarabadi buffaloes from various test-day milk yield data retrieved for different time intervals. A total of 1,15,339 daily milk yield records in 176 lactations of 1st to 6th parity of 30 Jaffarabadi buffaloes lactating at the Cattle Breeding Farm, Kamdhenu University, Junagadh, Gujarat over a period of 28 years (1991 to 2018) were used for the study. Single monthly test-day milk yield recorded on 125th, 155th or 185th day i.e., 5th, 6th and 7th monthly test day yield alone provided only 50% reliability in determining the standard lactation milk yield. Daily peak yield alone was also found to be a poor predictor for lactation yield. Prediction equations using combination of consecutive two monthly test day yields from 4th to 10th monthly test day were found reliable source for prediction of lactation milk yield providing accuracy up to 82.19% whereas, daily peak yield in combination with single monthly test day yield at mid and late lactation was also predicted lactation milk yield with accuracies up to 72.23%. Milk production recorded at weekly interval could also be used to approximate milk production using the equation 15.35+6.91 × Sum of all weekly test-day yields, with precision of 98.93% or milk production recorded at fortnightly interval by the equation 18.04+14.65 × Sum of fortnightly test-day yields, with precision of 97.14%.&#x0D;

Whole blood transcriptome analysis of lactating Murrah buffaloes divergent to contrasting genetic merits for milk yield

Functional genome profiling of Murrah buffaloes (Bubalus bubalis) was performed for milk-production trait by whole blood transcriptome analysis comparing RNA-seq data assembled from high and low milk producing multiparous (5 -6 parity) animals. These buffaloes reflected the genetic merit inherited as daughters born to extremely high- and low-end bulls evaluated under a progeny testing scheme and ranked by the estimated breeding value. The average standard milk yield (SMY) over the 305 d during the parity was recorded as 2909.50L ± 492.63 and 1869.57 ± 189.36L in high- and low-performance buffaloes, respectively. The “reference” assembly data was assembled from transcriptome libraries of a group of buffaloes (n=16), comprising of animals in different physiological states. Replicates selected within each category of the high and low genetic merit animals showed a correlation coefficient of high order (R2=0.98) while comparing with the `reference' assembly. The sequence data of selected buffaloes, mapped over the Mediterranean water buffalo genome, revealed differentially expressed genes (DEGs) distinctly depicted via heat maps and volcano plots obtained for two categories of animals, determining more than 25,000 genes via the Cufflink analysis. DEGs included 83 down-regulating and 142 up-regulating genes (p&amp;lt;0.05, FDR&amp;lt;0.05). Functional classification of the DEGs revealed a fine networking of biological processes, primarily cell signaling, cell proliferation, cell differentiation, RNA splicing, fat metabolism, and inflammasome generation. These processes are regulated by transcription factors and binding proteins covered under the network of TNF alpha signaling, NF-kappa B signaling and MAPK PI3K-AKT signaling pathways/ cascade emerged as main biological pathways. Emerged pathways revealed remarkably intricate tuning of metabolic and cell development processes converging into milk production in buffaloes. Segregated patterns of gene expression obtained for high and low milk producing buffaloes using the non-invasive method of whole blood transcriptome analysis has emerged as a promising resource comprising gene network and protein -protein interactions, primarily involved in lactation. Synergism of transcription factors and binding proteins promoting epigenetic regulation at all development stages of mammary tissue induce mammogenic and lactogenic responses for subsequent milk secretion under optimum feeding management. These findings may help improve breeding strategies to achieve the desired milk yield in Murrah buffaloes.

Influence of non-genetic factors on first lactation and lifetime performance traits in Nili-Ravi buffaloes

The objective of this research was to evaluate the effects of various non-genetic factors on first lactation and lifetime productivity in Nili-Ravi buffaloes, including season of birth, period of birth, age at first calving, season of first calving, period of first calving, and number of lactations completed. The livestock data on first lactation and lifetime performance traits relevant to 501 Nili-Ravi buffaloes were collected from the history sheet of the animal for a period from 1983 to 2017 (i.e., 35 years) and maintained at the Indian Council of Agricultural Research—Central Institute for Research on Buffaloes (ICAR-CIRB) sub-campus, in Nabha, Punjab, India. To evaluate the least-squares means (LSMs) and the effect of non-genetic factors on performance traits, a least-squares analysis model was applied. The overall LSM for age at first calving (AFC) was 45.03 ± 0.40 months and ranged from 34 to 54 months. The results indicated that the effect of AFC was highly significant (p ≤ 0.01) on first lactation total milk yield (FLTMY), first lactation standard milk yield (305 days or less) (FLSMY), first peak milk yield (FPY), and first lactation length (FLL) in the Nili-Ravi breed of buffaloes. FLTMY, FLSMY, and FPY were highest (2,250.08 ± 48.16 kg, 1,944.68 ± 31.20 kg, and 9.32 ± 0.16 kg/day, respectively) for animals with an AFC of 42–48 months. Furthermore, FLTMY, FLSMY, and FLL were highest (2,411.02 ± 68.68 kg, 2,008.81 ± 44.49 kg, and 357.43 ± 8.13 days, respectively) in animals that first calved in the autumn season. However, the lowest first dry period (FDP), first service period (FSP), and first calving interval (FCI) (110.63 ± 7.42 days, 125.48 ± 9.04 days, and 443.63 ± 9.00 days, respectively) were found for animals that first calved in the rainy season. The overall LSM for herd life (HL), productive life (PL), productive days (PDs), unproductive days (UDs), total lifetime milk yield (total LTMY), standard lifetime milk yield (standard LTMY), milk yield per day of productive life (MY/PL), milk yield per day of productive days (MY/PDs), and milk yield per day of herd life (MY/HL) were estimated as 3,779.84 ± 31.86 days, 2,078.55 ± 24.32 days, 1,552.74 ± 20.06 days, 525.81 ± 12.44 days, 10,229.71 ± 195.31 kg, 9,203.64 ± 173.52 kg, 4.86 ± 0.08 kg/day, 6.46 ± 0.08 kg/day, and 2.66 ± 0.04 kg/day, respectively. The effect of AFC on HL, PDs, UDs, total LTMY, and standard LTMY was highly significant (p ≤ 0.01). Furthermore, the effect of season of first calving on HL, PL, and PDs was significant (p ≤ 0.05). In addition, the effect of the period of first calving on HL, PDs, standard LTMY, and total LTMY was significant (p ≤ 0.05). In these contexts, it can be concluded that the buffaloes of the Nili-Ravi breed with an AFC of 42–48 months performed better than animals with a later AFC in terms of production, reproduction, and lifetime traits.

Impact of Calving Difficulty on Lameness in Dairy Cows

The aims of our study were to evaluate the associations between calving difficulty and lameness and their effects on milk yield and quality traits. A total of 4723 calving cases were evaluated for calving difficulty using a 4-point scoring system. Lameness was diagnosed with a visual locomotion score system from 1 to 30 days after calving in 333 fresh dairy cows. Cows were divided into non-lame cows and lame cows. Milk quality traits were registered using Lely Astronaut® A3 milking robots. The normal distribution of all indicators was assessed using the Shapiro–Wilk normality test. Normally distributed milk indicators were expressed as mean ± standard error of the mean. Differences between the mean values of their groups were determined using the Fisher’s least significant difference test. We categorized cows by health status, i.e., lame (LA) and non-lame (HL) cows, and according to calving difficulty (CD) (on a 4-point scale: 1—no problem, 2—slight problem, 3—problems requiring assistance, 4—considerable force and extreme difficulty). In the present study, calving difficulty increased the risk of lameness in cows by 2.09-fold (95% CI = 1.644–2.650, p &lt; 0.001). It was found that the mean standard milk yield in fresh dairy cows with calving difficulty was lower (−6.14 kg, p &lt; 0.001) than in the group where no assistance was required at calving. Similarly, herd affected milk fat (%) and the calving process—herd and the interaction between calving difficulty and herd—and lameness impacted the quantity of milk protein and lactose in cows. We found that severe lameness (3–4 points) (3.88–5.92% of cows) became more prevalent in those cows that had dystocia than those that did not (0.27–2.37% of cows).

Comparison of Two Methods of Predicting 305-day Milk Yield for Genetic Evaluation to Design a Tunisian Holstein Reference Population

Various standardized milk yield prediction methods have been developed and used. The objective of this study was to compare two methods for the estimation of 305-day milk yield inthe Holstein breed, in terms of breeding values and their accuracy. Genetic evaluations of milk yield were compared using: 1) adjusted total lactation yield for days in milk, month, and age at calving (adjusted TY305) or 2) adjusted305-day milk yieldestimated by fitting test-day(TD) records to the Wood model(adjusted WY305).The method with better ability to predict standardized milk yield was used to identify a Tunisian cow reference population toward genomic evaluation of milk trait. Three datasets were used. The first data contains 380’709 TD records corresponding to 34’281 three first lactations of 20’758 cows collected between 2008 and 2018 in 33 herds. The second dataset contains 11’175 total first three lactation yields recorded between 2012 and 2017 from 6251 cows belonging to 33 herds.The third data is a pedigree file of 27’487 males and females. The predictive ability of the two methods was assessed by Spearman’s rank correlation between predicted breeding values for 305-day milk yield (PBV305) from the full dataset and reduced dataset in which the records from the last calving year were masked. The two methods were compared in terms of rank correlation between PBV305 and the percentage of selected animals in common when different selection intensities were applied based on PBV305.The average gain in accuracy was calculated and a Tunisian reference population was identified. The results showed that heritability estimates were 0.11 (±0.02) and 0.13 (±0.01) for adjusted WY305 and TY305, respectively. The highest correlation for PBVs between full data and reduced data was achieved in TY305 dataset. Rank correlations between PBV305 estimated for adjusted WY305 and TY305 were 0.67. The percentage of animals selected in common was 11% or 21%, respectively, when 1 or 5% of cows were chosen as future dams of bulls, according to PBVs. An average gain in accuracy of 15% was observed for cows when using adjusted TY305 to estimate PBVs for milk yield trait. The obtained results showed that adjustments applied to the total milk yield records could be appropriate for 305-day milk yield prediction and genetic evaluation of milk production in the Tunisian Holstein population. Based on two main designs (extreme yield and top accuracy), a total of 1000 cows were selected to form the Tunisian female reference population using adjusted TY305 records.

Association between age at first calving, first lactation traits and lifetime productivity in Murrah buffaloes.

ObjectiveThis study was conducted to estimate the association of age at first calving (AFC) with first lactation traits as well as lifetime performance traits in Murrah buffaloes.MethodsData on first lactation and life time performance of Murrah buffaloes (n = 679), maintained at Indian Council of Agricultural Research-Central Institute for Research on Buffaloes, Hisar, India during the period 1983 through 2017, were deduced to calculate heritability estimates, genetic and phenotypic correlation of different first lactation and lifetime traits. The univariate animal model was fitted to estimate variance components and heritability separately for each trait, while bivariate animal models were set to estimate genetic and phenotypic correlations between traits under study.ResultsThe heritability was high for first peak milk yield (FPY, 0.64±0.08), moderate for AFC (0.48±0.07) and breeding efficiency (BE 0.39±0.09). High genetic correlations of first lactation total milk yield (FLTMY) with first lactation standard milk yield (FLSMY, 305 days or less), FPY, and first lactation length (FLL) was seen. Likewise, genetic correlation of AFC was positive with FLTMY, FLL, first dry period (FDP), first service period (FSP), first calving interval (FCI), herd life (HL) and productive days (PD). Significant phenotypic correlation of FLTMY was observed with HL, productive life (PL), PD, total lifetime milk yield (LTMY), standard lifetime milk yield (standard LTMY). Moreover, positive genetic and phenotypic correlation of FPY was observed with HL, PL, PD, total LTMY and standard LTMY.ConclusionThis study reports that AFC had positive genetic correlation with FDP, FSP, FCI, and unproductive days while, negative association of AFC was observed with FLSMY, PL, total LTMY, standard LTMY, and BE. This suggests that reduction of AFC would results in improvement of lifetime performance traits.

The Effects of Reproductive Disorders, Parity, and Litter Size on Milk Yield of Serrana Goats.

Simple SummaryThis study aimed to evaluate the effects of reproductive disorders, parity, and litter size on a 150-day standardized milk yield of the Transmontano ecotype of the Serrana goat breed (a dual purpose breed) over a three decade period. The 150-day standardized milk yield was significantly influenced by all studied factors and their interactions. The milk yield reduction due to reproductive disorders was more intense in primiparous than multiparous goats, and in primiparous or multiparous goats of the Transmontano ecotype presenting multiple fetuses, than in those presenting singletons. This milk production pattern proves that the lactation following abortion is viable for production purposes and an improvement of production system management can play an important role in mitigating milk yield losses.Several reproductive factors may affect milk yield in goats. The main aim of this study was to evaluate the influence of reproductive disorders, parity, and litter size, and their interactions on the 150-day standardized milk yield (SMY150) of low-producing dairy goats extensively raised. A total of 148,084 lactations between 1993 and 2015 were obtained from data of the Genpro pedigree records of the Transmontano ecotype of Serrana goat breed. The presence or absence of reproductive disorders (RD) from late (>half) pregnancy (abortions followed by lactation) or at kidding, number of fetuses (single vs. multiple), and parity (primiparous vs. multiparous) of the Transmontano ecotype of Serrana goat were used as fixed effects to fit a general linear model for a SMY150 output. A significant effect (p < 0.001) of all factors on SMY150, as well as three-way interactions, were observed. The SMY150 reduction subsequent to RD was 3.7% for multiparous and 9.6% for primiparous goats carrying singletons, and 14.1% for multiparous and 18.8% primiparous goats carrying multiple fetuses. It was concluded that a new lactation following abortion occurrence is viable for production purpose in low-producing dairy goats under pastoralism. Nevertheless, the impact of RD on SMY150 varied according to the number of fetuses and the parity of the Transmontano ecotype of Serrana goats. This information should be used in decision-making practices regarding reproductive and herd health management.

Modeling of lactation curves for prediction of standard lactation milk yield in Marathwadi buffaloes

The present study was carried out on 538 monthly milk yield records of Marathwadi buffaloes maintained at Cattle Breeding Farm, College of Veterinary and Animal Sciences, Udgir Dist-Latur Maharashtra spread over a period of 9 years. The monthly milk yield was recorded at 6th, 36th, 66th and so on till standard lactation with 30 days interval. The goodness of fit of 3 lactation curve models, viz. parabolic exponential function, inverse polynomial function and mixed log function were used on monthly milk yields in Marathwadi buffaloes. The highest coefficient of determination for fitting of lactation curve models was with mixed log function (97.63%), followed by parabolic exponential function (95%) and inverse polynomial function (82.70%). Further, the root mean square error was found least for mixed log function (1.70), followed by parabolic exponential function (3.55) and inverse polynomial function (4.61). It is therefore inferred that mixed log function fitted best for prediction and modeling of lactation curves based upon monthly milk yields.

Ruminal microbiota composition associated with ruminal fermentation parameters and milk yield in lactating buffalo in Guangxi, China-A preliminary study.

The ruminal microbiota of 15 dairy buffalo was characterized using high-throughput 16S rRNA gene amplicon sequencing. Results showed that Bacteroidetes was the dominant bacterial phylum in all rumen samples, followed by Firmicutes, Proteobacteria, Tenericutes and Verrucomicrobia. Butyrivibrio was positively correlated with average milk fat yield (R=0.55; p=0.03), average milk total solid yield (R=0.56; p=0.03) and standard milk yield (R=0.52; p=0.05). Acinetobacter were positively correlated with average milk protein yield (R=0.56; p=0.03), average milk total solid yield (R=0.60; p=0.02) and standard milk yield (R=0.57; p=0.03). Acetobacter was positively correlated with acetate (R=0.63; p=0.01), propionate content (R=0.55; p=0.03), butyrate content (R=0.61; p=0.02) and total VFA (R=0.62; p=0.01). The phyla Proteobacteria (R=0.53; p=0.04) and genus Prevotella (R=0.52; p=0.05) were positively correlated with butyrate content. Correlation analysis suggested that increased Butyrivibrio and Acinetobacter residing in the buffalo rumen could improve milk performance.

Development of standard lactation milk yield prediction models using monthly milk yield records in Marathwadi buffalo

Development of standard lactation milk yield prediction models using monthly milk yield records in Marathwadi buffalo

Comparison of service period and lactation milk yields in dairy cows with single- and twin-calving

Introduction. Twin-calving occurs in 3 to 5 % of Holstein Friesian cattle, and it is mostly followed by reproductive and economic problems. This evaluation will compare the service period and the milk yield in cows with single and twin births at a Hungarian large-scale farm. Materials and Methods. The data were collected from 4223 cows between 2000 and 2010. In Cox?s regression model (service period) and general linear model (milk production traits), the type of calving (single/twin), the construction code (referring to the Holstein Friesian blood proportion), the season and number of calvings were fixed effects, and furthermore, the year of calving was a covariate. Results and Conclusions. This analysis showed there was no significant difference in the length of service period (SP) between the two groups of cows. The total lactation milk yield produced a meaningful difference in performance: single-calving cows had greater milk yield (p=0.013), fat yield (p=0.030), and protein yield (p=0.028) than cows with twins. The standard lactation milk yield showed the same tendency at a stronger significance and a lower level of production. This unexpected and contradictory result in service period could be explained by the much longer period of open days in twinning cows, known from previous research. Regarding milk yield, an involuntary decrease for cows after twin calving was confirmed.

Artificial Intelligence for Prediction of Standard Lactation Milk yield in Deoni Cattle

A study was carried out on 1764 test day records of Deoni cattle breed located in cattle breeding farm, College of Veterinary and Animal Sciences, Udgir Dist- Latur Maharashtra, the western state of India. A multilayer feed forward neural network with back propagation of error learning mechanism was developed using artificial neural network. The network was trained and simulated using Bayesian regularization (BR) algorithms. The performance efficiency of the network model was evaluated using the value of coefficient of determination (R2-value) and root mean square error. It was observed that, the mean value of test days varies from 1.13 to 1.83 with standard deviation ranged from 0.50 to 1.01. Test day nine contributes highest (87.57%) to the total variability. The highest coefficient of determination i.e. 89.55 % was explained in fourth set with 2 layers and 10 neurons. It was inferred that, standard lactation milk yield of Deoni cows could be predicted on the basis of monthly test day milk records as early as 155th days of lactation with 89.55 % of coefficient of determination and 0.138 of root mean squares error.

Genetic and Environmental Correlation of Age at First Calving with Various Production Traits in Gir Cattle

The main objective of this study was to estimate genetic and environmental correlations between Age at First Calving and various production traits in Gir cattle. The production traits studied were: Standard Lactation Milk Yield, Peak Milk Yield, Lactation Length and Dry Period. The production records on 345 Gir cows with 1257 lactations sired by 52 bulls, maintained at Cattle Breeding Farm, Junagadh, Gujarat, over 24 years (1987–2010) were studied. The analysis revealed positive environmental correlation of Age at First Calving with Lactation Length (0.224 ± 0.234) and Dry Period (0.039 ± 0.195), while negative environmental correlation of Age at First Calving with Standard Lactation Milk Yield (-0.194 ± 0.178) and Peak Milk Yield (-0.070 ± 0.200). Genetic correlation of Age at First Calving with Standard Lactation Milk Yield (0.006 ± 0.178), Peak Milk Yield (0.069 ± 0.200), Lactation Length (0.752 ± 0.234) and Dry Period (0.058 ± 0.195) were found during this study, in which genetic correlation between Age at First Calving and Lactation Length was found highly significant. These indicated that selection for Age at First Calving would not reflect upon Standard Lactation Milk Yield and Peak Milk Yield.

English

This study was conducted in five dairy farms with different capacity (farms A with 47, B 12, C 10, D 14 and E 24 Simmental cows, aged between 4 and 5 years and body weight about 600 kg) in order to determine a relationship between rearing system, Animal Needs Index (ANI) and milk traits. Loose system of cow rearing was used in open stalls in farms A and C, while in other farms cows were tied in closed stalls. In two farms, there were outdoor pens, permanently available to cows on farm A, and during daytime on farm D. Rations for dairy cows were equal in all five farms and suitable for daily milk production about 20 kg with 4.0 % milk fat and 3.5 % milk protein. It was established that total ANI scores for farms were A 35.5, B 9.5, C 24.5, D 26.5 and E 10.5. The welfare levels in farms B and E were not sufficient, in farms C and D were very good, while in farm A it was excellent. A very significant influence of rearing system on cow welfare was found (p<0.001). A significant influence of rearing system (p<0.01) on average daily milk yield, milk yield in standard lactation, milk fat (kg), yield of 4 % fat corrected milk and yield of proteins (kg) were noticed. The influence of the rearing system on milk fat content (%), dry matter (%), protein (%) and lactose (%) was not statistically significant. Differences between ANI score, daily and standard lactation milk yield were very significant (p<0.001), as well as differences between ANI and the amount of milk fat (kg), protein (kg) and amount of 4 % fat corrected milk.

Association between body and udder morphological traits and dairy performance in Spanish Assaf sheep

Abstract. The relationship between 17 body and 8 udder measurements and phenotypic dairy performance were studied using information from 280 Spanish Assaf ewes from 2 to 4 years old belonging to 18 flocks. The influence of the environmental area on the dairy traits was assessed by fitting a fixed model including the flock effect and the age effect. A factor analysis was also carried out to determine the lowest number of independent factors that account for most of the variation in the traits. The flock was statistically significant for performance trait and predicted breeding value (PBV) while the age was only significant in 150 days standardized milk yield (MY150) and daily milk yield (DMY). In general, not much association was found between morphological and dairy performance traits. Few body traits showed significant phenotypic correlations; mainly those related to height, diameters, ears and tail, with the latter being the most correlated but unfavourable for DMY and PBV. Among udder conformation, udder depth and length were the most correlated traits to milk production, while deep udders and short teats were related to lower somatic cell counts. The different traits were classified for analyses into six factors relating mainly to: live weight; production and udder traits; cheese production; stature; teats and udder health; and udder dimensions. Trade of animals was concluded to be unreasonably based on morphological or even on performance traits. The participation of breeders in an appropriate breeding scheme based on accurate genetic evaluations is encouraged.

Relación entre la vida productiva y la producción de leche en la raza Assaf Española

Relationship between length of productive life and the milk production in the Spanish Assaf sheep breed The Spanish Assaf sheep breed has a National Breeding Program based on increasing milk production per lactation and its quality. This research attempts to determine the relationship between milk yield and length of productive life (number of lactations registered to culling) of the breed, using historic data from official dairy recording system until 2011. For each individual (27.170 dead and 36.268 alive animals) the average value of 150d standardized milk yield was calculated. Analysis of variance (GLM procedure of SAS) of milk production was performed using different models based on the state of sheep (alive or dead), flock, average type of birth, average number of dry days, and productive life. The average value of productive life was 3.76 lactactions/sheep (55.3% of the animals had between 2 and 3 lactations recorded to low). The results showed an increase in milk production over the years and a reduction of productive life.

ホルスタイン種牛群における管理指標としての標準乳量算出モデルの検討

ホルスタイン種牛群における管理指標としての標準乳量算出モデルの検討