Persistency Of Milk Yield Research Articles

Lactation performances in primiparous Holstein cows following short and normal gestation lengths.

Despite decades of research, little is known regarding physiologic temporal limits for initiation of lactation in pregnant non-lactating cattle the aim of this study was to compare the lactation performances in primiparous Holstein cows after a short gestation length (GL) or abortion to those after a normal GL. The data were collected using an automated data collection system. The 94 herds evaluated were located in Belgium, France, Italy, the Netherlands and Germany. Data from a wide range of physiological cow-life events including birth and calving events, reproduction events (insemination, pregnancy checks, and abortions), and milking events were collected. The GL was defined as the interval between the last insemination and the subsequent calving (or abortion) within a range of 150-297 days. Animals were categorized into one of five categories based on GL quantiles (C-I to C-V). Lactation curve parameters including the scale, ramp, and decay were estimated using the Milkbot model. Then, the derived 305-day milk yield (M305-d), peak yield, and time to peak were compared between different GL categories. Of 13,732 lactations, 15 (0.11%) were found with a GL shorter than 210 days (ranging from 158 to 208 days). The 305-day milk yield was significantly lower in the C-I (7,566 ± 186) and C-II groups (7,802 ± 136 kg), compared to the C-III (8,254 ± 116 kg), C-IV (8,148 ± 119 kg), and C-V (8,255 ± 117 kg) groups. The same trends were found for the scale and peak yield of the lactation; the lowest scale were found for the C-I (31.5 ± 0.73) and C-II (32.8 ± 0.53) groups, and the highest were found for the C-III (34.5 ± 0.46), C-IV (34.9 ± 0.45), and C-V (35.0 ± 0.45) groups. Peak yield increased significantly from C-I (27.8 ± 0.66 kg) and C-II group (28.8 ± 0.48 kg) to the C-III (30.2 ± 0.42 kg) and further to the C-IV (30.6 ± 0.40 kg) and C-V (30.6 ± 0.41 kg) groups. Moreover, primiparous cows in the C-II GL category showed a higher milk yield persistency (decay of 1.30E-4 ± 3.55E-5) compared to those belonging to the C-IV (decay of 1.38E-4 ± 2.51E-5) and C-V (decay of 1.38E-4 ± 2.58E-5) group. In conclusion, results showed that primiparous cows with a shorter GL produced significantly less 305-day milk and peak yields, had a higher lactation persistency, and showed a lower upward slope of the lactation curve compared to those with a normal GL.

Genetic aspects of Wood's lactation curve parameters in Jersey crossbred cattle using Bayesian approach.

The study was undertaken to estimate the genetic parameters of lactation curve parameters of Wood's function in Jersey crossbred cattle using the Bayesian approach. Data on 33,906 fortnightly test day milk yields of 1,718 lactation records of Jersey crossbred cows, maintained at the ICAR-National Dairy Research Institute in West Bengal, were collected over a period of 40 years. The lactation curve parameters including 'a' (initial milk yield after calving), 'b' (ascending slope up to peak yield) and 'c' (descending slope after peak yield) and lactation curve traits, peak yield (ymax), time of peak yield (tmax) and persistency of milk yield (P) of individual cow for each lactation were estimated using the incomplete gamma function (Wood's model) by fitting the Gauss-Newton algorithm as an iteration method using PROC NLIN procedure of SAS 9.3. Variance components and genetic parameters of lactation curve parameters/traits were estimated by a repeatability animal model using the Bayesian approach. Estimates of heritabilities were found to be 0.18 ± 0.05, 0.09 ± 0.03 and 0.11 ± 0.04 for parameters 'a', 'b' and 'c', respectively and 0.24 ± 0.05, 0.12 ± 0.04, and 0.15 ± 0.05 for ymax, tmax and P, respectively. Repeatability estimates were 0.31 ± 0.03, 0.21 ± 0.04 and 0.30 ± 0.04 for parameters 'a', 'b' and 'c' respectively and 0.39 ± 0.03, 0.24 ± 0.03 and 0.37 ± 0.03 for ymax, tmax and p, respectively. Genetic correlations among lactation curve parameters/traits ranged from -0.75 to 0.95. Existence of genetic correlations among lactation curve parameters/traits indicated substantial genetic and physiological relationships among lactation curve parameters/traits of Jersey crossbred cattle.

Lactation performance of dairy cows on feeding rumen-protected choline

The experiment was designed to assess the effect of supplemental feeding of 40 g/day rumen-protected choline (33.5% w/w) in the total mixed ration of lactating cows on nutrient intake, lactation, reproduction, feed efficiency, and feed cost during 294 days of the lactation. The study was conducted at Livestock Research Station, Anand during 2018 to 2021. A total of sixteen cows were randomly distributed into two groups of eight each based on descending order of previous standard lactation yield and lactation numbers. An intake and milk yield were calculated for 1-21 biweekly periods. The milk composition was assessed four times during lactation. The body condition score (BCS) on a 1-5 point scale with an increment of 0.25 points was measured at -21, -14, -7, 0, 7, 14, 21, 35, 49, 63, 91, and 119 days of calving. The supplemental feeding of rumen-protected choline (RPC) in T2 group resulted in lower nutrient intake, lesser insemination to conceive, and service period with higher 4% fat corrected milk (FCM) yield in dairy cows. The body condition score and milk yield persistency were higher along with improved feed efficiency and feed economics in the T2 group as compared to the T1 group. The daily feeding of 40 g RPC during -21 to 120 days of calving resulted in significantly lower nutrient intake with improved 4% FCM yield, reproductive performance, feed efficiency, and feed economics in dairy cows.

Effect of Breeds on Milk Yield and Persistency of Cows Raised under Extensive Management System in Nigeria

Milk persistence in dairy cows is an economically important trait that will determine profit for the dairy industry and will help to overcome immeasurable diseases in dairy. cows. This study looked at the best breed that will maintain persistency for a certain time and ranked the animals based on milk yield and persistency. The study used a total of 60 nursing cows, 20 Sokoto Gudali, 20 White Fulani, and 20 Red Bororo were used for the daily milk collection. The total milk collected in a week was added together and divided by seven days to get the average daily milk yield for each breed (Sokoto Gudali, White Fulani and Red Bororo). The duration of the milking periods was recorded in days. Persistency of milk yield was computed by the ratio of the lactation period and divided into four equal periods of 30 days each. The total 30-day milk yield of each period per cow was calculated. Data collected were analyzed using the general Linear Model of the SAS program while significant means were separated using the Duncan Multiple Range Test. The results revealed that the Sokoto Gudali cows yielded significantly (P < 0.05) higher daily milk (4.13 - 4.31 L/day) whereas Red Bororo (0.72 - 0.94 L/day) was lowest in week 1. At week two, Sokoto Gudali (4.09 - 4.31 L/day) had the highest milk whereas Red Bororo (0.82 - 1.04 L/day) was the least. At week three, Sokoto Gudali (4.19 - 4.39 L/day) had a significantly (P < 0.05) higher daily milk whereas Red Bororo (0.74 - 0.90 L/day). In week 4 same trends were also observed. Sokoto Gudali (4.19) was ranked to be superior (1), followed by the White Fulani (1.62) with the breed (2) whereas the Red Bororo (0.89) was the least (3) in terms of total milk yield. The average weekly milk yield persistency showed that Sokoto Gudali and the Red Bororo breeds were maintained at high persistency from week one through week four without a significant decline. Breeds influenced daily milk yield from week 1 to week 4. The overall ranking of breeds on milk yield revealed that Sokoto Gudali was ranked the highest followed by White Fulani and the least was Red Bororo.

Validation of single-step genomic BLUP random regression test-day models and SNP effects analysis on milk yield in French Saanen goats

The shape of the lactation curve is linked to an animal's health, feed requirements, and milk production throughout the year. Random regression models (RRM) are widely used for genetic evaluation of total milk production throughout the lactation and for milk yield persistency. Genomic information used with the single-step genomic BLUP method (ssGBLUP) substantially improves the accuracy of genomic prediction of breeding values in the main dairy cattle breeds. The aim of this study was to implement an RRM using ssGBLUP for milk yield in Saanen dairy goats in France. The data set consisted of 7,904,246 test-day records from 1,308,307 lactations of Saanen goats collected in France between 2000 and 2017. The performance of this type of evaluation was assessed by applying a validation step with data targeting candidate bucks. The model was compared with a nongenomic evaluation and a traditional evaluation that use cumulated performance throughout the lactation model (LM). The incorporation of genomic information increased correlations between daughter yield deviations (DYD) and estimated breeding values (EBV) obtained with a partial data set for candidate bucks. The LM and the RRM had similar correlation between DYD and EBV. However, the RRM reduced overestimation of EBV and improved the slope of the regression of DYD on EBV obtained at birth. This study shows that a genomic evaluation from a ssGBLUP RRM is possible in dairy goats in France and that RRM performance is comparable to a LM but with the additional benefit of a genomic evaluation of persistency. Variance of adjacent SNPs was studied with LM and RRM following the ssGBLUP. Both approaches converged on approximately the same regions explaining more than 1% of total variance. Regions associated with persistency were also found.

Reducing milking frequency from 3 to 2 times daily in early lactation: effects on milk production, health and body condition.

The objective of this experiment was to investigate the effect of reducing early lactation milking frequency on milk yield and persistency through lactation and early lactation fat mobilization, measured by body condition score (BCS) and BHB in milk. We hypothesized that milking cows twice per day in early lactation before milking them 3 times per day for the remaining lactation would cause less fat mobilization in early lactation, a lower peak milk yield but improved persistency throughout lactation compared with milking cows 3 times per day for the entire lactation. The experiment took place on 2 commercial dairy farms in Denmark. All cows calving in a period of nine months (n = 239) in their current first and later parities were randomly allocated at dry-off to 1 of 3 treatments based on expected calving date. The treatments were (1) cows milked 2 times per day for 1 week after calving, (2) cows milked 2 times per day for 4 weeks after calving and (3) cows milked 2 times per day for 7 weeks after calving. All cows were then milked 3 times per day for the remaining lactation. Milk yield peaked 3.3 and 3.6 d later and milk yield persistency improved with 18 and 19 g per day when cows were milked 2 times per day for 4 and 7 weeks, respectively, compared with milking 2 times per day for 1 week after calving. We found a significant highest milk BHB in treatment 2, but the underlying effect of milking cows 2 times per day for 4 weeks compared with 1 or 7 weeks was unclear. In conclusion, we did not confirm our hypothesis that milking cows 2 times per day compared to 3 times in early lactation would reduce fat mobilization and reduce peak yield. We did, however, find an improved milk yield persistency, which partially offset a numerical reduction in peak yield, and hence there was no significant effect of reducing early lactation milking frequency on total lactation (305 DIM) milk yield.

Test day yield, lactation curve and production potential of Gir cattle under hot and humid conditions of Tamil Nadu

Test day milk yield records (5130), milk production and milk composition traits from 19 lactations of Gir cows collected for two years (2019 and 2020) were used to understand the performance of Gir breed in hot and humid conditions of Tamil Nadu. Different lactation curve models were used for modelling test day records and model diagnostics like adjusted R-square, BIC and RMSE were used to obtain the model of best fit. The mean test day yield, fat per cent, SNF (%), total milk yield, peak yield, days to attain peak yield and calving interval observed were 5.78 kg, 5.05%, 7.65%, 1507 kg, 9.23 kg, 46.5 days and 447 days respectively. Ali and Shaeffer model offered the best fit for lactation curve in Gir cows. Mahadevan method and Gamma function were used to calculate the persistency of milk yield which was obtained as 1.33 and 6.348 respectively. Results of the study indicated that Gir cattle were able to adapt themselves through maintenance of reproductive traits comparable with that of the native tract but the new humid environment has caused a slight decrease in the performance of milk production traits.

Estimation and comparison of different lactation persistency methods in Tharparkar cattle

The present study was undertaken to estimate the various measures of lactation persistency and to estimate effect of various non-genetic factors affecting the persistency of milk production and comparison of different persistency indices using standard error as percentage of mean in Tharparkar cattle. Total 322 lactation records of 138 Tharparkar cattle were collected from Animal Genetics and Breeding Division of National Dairy and Research Institute, Karnal from 1996 to 2018 for the estimation of lactation persistency. Lactation persistency was estimated using Ratio method (P1), Prasad method (P2), Solkner and Fuchs variation method in 200 days (P3) and 305 days (P4).The least squares of means for persistency of milk yield were 149.6 ± 3.07, 0.53 ± 0.007, 1.83 ± 0.05 and 2.28 ± 0.07 in P1, P2, P3 and P4 respectively in Tharparkar cattle. Based on standard error as percentage of mean, the best method was Prasad method (1.1%). The highest values of least squares means were found for first calvers in P1 but in P3 and P4 fourth calvers were more persistent. The cows calved during rainy season were more persistent as estimated by P1 and P2 but based on P3 and P4 winter calvers were more persistent. There was a highly significant (P<0.05) positive correlation of total milk yield with all the method of persistency indices.

The evaluation of the relationship of lactose to production and reproduction traits in different breeding conditions of the Slovak Spotted dairy cows

The evaluation of the relationship of lactose to production and reproduction traits in different breeding conditions of the Slovak Spotted dairy cows

Association of lactation persistency with genetic variants of bovine growth hormone gene in Indian Sahiwal cows

The aim of this study was to determine the associations of persistency with genetic variants of bovine growth hormone (bGH) gene in Indian Sahiwal cows. The data pertaining to the monthly test day milk yield (MTDMY) and first lactation length (FLL) of 305 lactating Sahiwal cows over a period of 23 years (1993–2016) were subjected to analysis. Persistency of milk yield was estimated by using test day based ratio method and Wilmink b function. Mean LL was 220.06±8.15 days in all studied Sahiwal cows, however, 276.67±10.25 days in cows with ≥100 days of LL and having 500 kg MY. The peak of milk yields was achieved at third TD of the first lactation. Macrophage stimulating protein 1 (MspI) and Arthrobacter luteus1 (AluI) restriction endonucleases were used to digest the amplified regions in intron 3 and exon 5, respectively of bGHgene. The bGHMspI restriction fragment length polymorphism (RFLP) yielded TT, CT and CC genotypes, whereas bGH-AluIRFLP yielded CC, CG and GG genotypes. Significant association was found between first lactation persistency estimated using test day based ratio method and bGH-MspI polymorphism. No significant association was found between first lactation persistency and bGH-AluI polymorphism. In summary, results of present study revealed that the TT genotype of bGH–MspI gene in Sahiwal cows has better lactation persistency than other genotypes.

Estimation of genetic parameters for dairy traits and somatic cell score in the first 3 parities using a random regression test-day model in French Alpine goats

Lactation curve shape can affect an animal's health, feed requirements, and milk production throughout the year. We implemented a random regression model for the genetic evaluation of lactation curve shapes of dairy traits in French Alpine goats for their first 3 parities. Milk, fat, and protein yields, fat and protein contents, somatic cell score, and fat/protein ratio were considered. The data consisted of test-day records from 49,849 first lactation Alpine goats during their first 3 lactations. The reference model used a Legendre polynomial of order 2 for each parity to describe the genetic and permanent environmental effects, and was compared with a model that combined the second and third parities. A rank reduction of the variance-covariance matrix was also performed using an eigenvalue decomposition for each parity from the 2 models. Genetic parameters were consistent between the models tested. With a reduction to rank 2 and combining the second and third parities, the first 2 principal components correctly summarized the genetic variability of milk yield level and persistency, with a near-nil correlation between the 2, and with a much shorter computation time than the reference model. A favorable correlation of +0.43 between milk yield persistency and fat/protein ratio persistency at the beginning of the lactation was found from buck estimated breeding values.

Assessment of lactation curve parameters for test-day milk yield, Fat% and SNF% in Murrah Buffalo

A lactation curve can reveal abundant information about the pattern and persistency of lactation in an individual dairy animal. Identifying buffalo with particular pattern and persistency of lactation milk yield can serve as additional selection criterion for a dairy herd. Wood’s incomplete gamma function fitted well to the monthly test-day milk, fat% and SNF% yields of Murrah buffaloes and can be used in prediction of milk and milk constituents yield with higher accuracy. We also report that exponential function (Wilminks model) also can be used in prediction of milk constituents in Murrah buffaloes when constant k is changed in the model from 0.05 to 0.06 or 0.07. Thus, these functions can be used to make breeding and management related decisions particularly selection of desired and persistent buffaloes and thus improving the production of the herd by culling non-desired type of Murrah buffaloes.

Genetic parameters for first lactation dairy traits in the Alpine and Saanen goat breeds using a random regression test-day model

BackgroundRandom regression models (RRM) are widely used to analyze longitudinal data in genetic evaluation systems because they can better account for time-course changes in environmental effects and additive genetic values of animals by fitting the test-day (TD) specific effects. Our objective was to implement a random regression model for the evaluation of dairy production traits in French goats.ResultsThe data consisted of milk TD records from 30,186 and 32,256 first lactations of Saanen and Alpine goats. Milk yield, fat yield, protein yield, fat content and protein content were considered. Splines were used to model the environmental factors. The genetic and permanent environmental effects were modeled by the same Legendre polynomials. The goodness-of-fit and the genetic parameters derived from functions of the polynomials of orders 0 to 4 were tested. Results were also compared to those from a lactation model with total milk yield calculated over 250 days and to those of a multiple-trait model that considers performance in six periods throughout lactation as different traits. Genetic parameters were consistent between models. Models with fourth-order Legendre polynomials led to the best fit of the data. In order to reduce complexity, computing time, and interpretation, a rank reduction of the variance covariance matrix was performed using eigenvalue decomposition. With a reduction to rank 2, the first two principal components correctly summarized the genetic variability of milk yield level and persistency, with a correlation close to 0 between them.ConclusionsA random regression model was implemented in France to evaluate and select goats for yield traits and persistency, which are independent i.e. no genetic correlation between them, in first lactation.

Estimation of genetic persistency of milk yield in Sahiwal cattle using random regression model

ABSTRACT Genetic persistencies of milk yield up to six parities were estimated for the first time in India to assess the sustainability of Sahiwal cattle. Monthly test day milk yield records of Sahiwal cattle were analyzed using Random regression model. Two different methods were used for estimation of genetic persistencies of milk yield, i.e. P1 and P2. Method P1 estimated genetic persistency as summation of deviation of estimated breeding value on days to attain peak yield from each test days after days to attain peak yield to different lactation days in different parities. P2 assessed genetic persistency as the extra genetic yield (gained or lost) from average days to attain peak yield to estimated breeding value on test days after attainment of peak yield relative to an average Sahiwal cattle having the same yield on days to attain peak yield. The overall mean genetic persistency on TD3, TD4, TD5, TD6, TD7, TD8, TD9, TD10 and TD11 was estimated as 0.103, 0.301, 0.583, 0.951, 1.396, 1.935, 2.561, 3.272 and 4.069, respectively, by P1 and 1.282, 5.384, 11.923, 21.249, 33.231, 47.794, 64.973, 83.997 and 99.484, respectively, by P2. An increasing trend in the values of genetic persistency was observed by both methods with increase in the days in milk. Sahiwal animals may be persistent for more lactation but due to less number of observations in seventh lactation only six lactations were considered in the present study.

Genetic and environmental relationships among milk yield, persistency of milk yield, somatic cell count and calving interval in Holstein cows

Background: Fertility and health traits, other than production traits, have a major role in the profitability of dairy cattle. Therefore, it seems necessary to include the afore mentioned traits in breeding programs. Hence, genetic parameters are needed to establish breeding plans. Objective: To estimate heritabilities as well as genetic and environmental relationships among total milk yield (TMY), persistency of milk yield (PMY), mean somatic cell count (SCC), mean loge somatic cell count (LnSCC), standard deviation of somatic cell count (stdSCC), and calving interval (CI) using two-trait and multi-trait analyses in Iranian Holstein. Methods: The dataset consisted of 25,883 first lactation records collected from 2002 to 2007 in 97 Holstein dairy herds in Iran. Four criteria of persistency of milk yield (PMY) were calculated using the Wood's gamma function. The WOMBAT1.0 software was used to estimate the (co)variance components using the Average Information Restricted Maximum Likelihood algorithm. Results: Total milk yield (TMY) resulted in the highest heritability estimate (0.29). Heritability estimates for different criteria of persistency of milk yield (PMY) ranged from 0.05 to 0.10. The unfavorable genetic correlation between TMY and calving interval (CI) was 0.71, while that of PMY with CI was 0.46. The estimated environmental correlations were lower than the genetic correlations for all traits, but the trends were generally similar. Conclusion: The results indicate that including PMY in the breeding goals could increase TMY and CI, and decrease somatic cell count (SCC).Keywords: breeding goal, correlation, fertility, heritability, Wood's gamma function. ResumenAntecedentes: Las características de fertilidad y salud, además de las de producción, tienen un papel importante en la rentabilidad de los hatos lecheros. Por lo tanto, parece necesario incluir los rasgos mencionados en los sistemas de mejoramiento. Por ende, los parámetros genéticos son necesarios para establecer planes de cría. Objetivo: Estimar la heredabilidad, así como las relaciones genéticas y ambientales entre el rendimiento total de leche (TMY), la persistencia del rendimiento lechero (PMY), el recuento medio de células somáticas (SCC), el recuento de células somáticas de loge promedio (LnSCC), la desviación estándar del recuento de células somáticas (stdSCC) y el intervalo de partos (CI) en vacas Holstein mediante análisis de dos rasgos y análisis múltiples. Métodos: Se analizaron registros de primera lactancia de 25.883 vacas Holstein, recolectados entre 2002 y 2007 en 97 rebaños lecheros de Irán. Se calcularon cuatro criterios de persistencia del rendimiento lacteo utilizando la función gamma de Wood. El software Wombat1.0 se utilizó para estimar los componentes de (co)varianza que emplean el algoritmo de máxima verosimilitud restringida de información promedio. Resultados: El rendimiento de leche (TMY) obtuvo la mayor heredabilidad estimada (0.29). Las estimaciones de heredabilidad para diferentes criterios de persistencia del rendimiento de la leche variaron de 0,05 a 0,10. La correlación genética desfavorable entre TMY e intervalo entre partos fue 0,71, mientras que la de PMY con el CI fue de 0,46. Las correlaciones ambientales estimadas fueron inferiores a las correlaciones genéticas para todos los rasgos, pero las tendencias fueron, en general, similares. Conclusión: Incluir el PMY en la meta de cría podría aumentar el TMY y CI, además de disminuir el recuento de células somáticas (SCC).Palabras clave: correlación, fertilidad, función gamma de Wood, heredabilidad, objetivo de cría. ResumoAntecedentes: As características de fertilidade e saúde, além das características de produção, têmum papel importante narentabilidade das vacas leiteiras. Por isso, parece necessário incluir as características já mencionadas nos sistemas de melhoramento genético. Assim, são necessários parâmetros genéticos para estabelecer planos de melhoramento genético. Objetivo: Estimar herdabilidade, bem como as relações genéticas e ambientais entre a produção total de leite (TMY), persistância da produção de leite (PMY), contagem médiade células somáticas (SCC), contagem média de células somáticas loge (LnSCC), desviopadrao da contagem média de células somáticas (stdSCC) e intervalo de pertosem (CI) vacas Holstein por duas análises de características e traços multiplos. Métodos: O conjunto de dados consistiuem registros de 25.883 vacas Holstein de primeira lactação coletadas de 2002 a 2007 em 97 rebanhos leiteiros em Iran. Foram calculados quatrocritérios de persistência da produção de leite utilizando a função gama de Wood. O software Wombat1.0 foi usado para estimar os componentes de (co)variância que empregam o algoritmo de máxima verossimilhança com informações restritas. Resultados: A maior herdabilidade (0.29) foi estimada para produção de leite. As estimativas de herdabilidade para diferentes critérios de persisténcia da produção de leite variaram 0,05 a 0,10. A correlação genética desfavorável entre o intervalo TMY eo intervalo de parto foi de 0,71 enquanto que a de PMY com CI foi de 0,46. As correlações ambientais estimadas foram inferiores às correlações genéticas para todos os traços, mas as tendencias foram geralmente semelhantes. Conclusão: Os resultados indicaram que a inclusão de PMY na meta de reprodução poderia aumentar TMY e CI, no entanto, diminuir a contagem de células somáticas.Palavras chave: correlação, fertilidade, função gama do Wood, herdabilidade, objetivo de criação.

Persistency of milk yield in Indonesian Holstein cows

Milk yield is an important trait in dairy industry; thus, information regarding this phenotype is essential to measure the productivity of a farm. Total milk yield in one lactation period was often predicted using information from samples collected within certain time intervals. The rate of change of milk production between two-time intervals is defined as persistency. This article aims to estimate the persistency of milk yield between lactation 1, 2 and 3 in Indonesian Friesian Holstein (IFH) cows. Data was collected from Limpakuwus stable, Baturraden Dairy Cattle Breeding Centre, Central Java Indonesia. Records were obtained from cows which started lactating on 2013 until the end of third lactation around the beginning of 2016. Milk yield from the first (L1), second (L2) and third (L3) lactations of 21 cows were recorded in kilograms. Samples were collected in 30 days basis interval started from the 10th day of lactation up to the 10th month. In this population, the cows first calving was around February – April 2013; while the second and third calving occurred all over the relevant year. The mean of milk yield for L1, L2 and L3 were 17.77±3.70, 16.09±5.17 and 13.73±4.02 Kg respectively. The peak of milk yields was achieved at the second month of the lactation for L1, L2 and L3. The persistency from the second to the tenth test days were 97, 93 and 94% for L1, L2 and L3, respectively. Milk yield persistency is representing ability of cow in maintain milk production after peak during lactation period. The more persistent shows better performance of dairy cattle as well as farm management. For that, persistency value could be used as valuable information in evaluating the management in Indonesian dairy farms.

Genetic analysis of persistency in HF crossbred cattle at an organized farm of northern India.

The present study was undertaken to estimate effect of various genetic and non-genetic factors on persistency of milk production and to identify the most appropriate persistency method that fits best in our environment. In the present study, effects of different non-genetic factors, viz. year, season, days to attain peak yield, and genetic group based on the level of exotic inheritance on persistency of milk yield in crossbred cattle were studied. Data comprised of 686 first lactation daily milk yield records of crossbred cattle that were maintained at GADVASU dairy farm over a period of 25years from 1991 to 2015 were utilized to calculate persistency coefficients by four methods, viz., Ludwick and Peterson method (P1), Mahadevan method (P2), ratio method (P3), and Prasad et al. method (P4). Overall least squares means for persistency by Ludwick and Peterson method (P1), Mahadevan method (P2), ratio method (P3), and Prasad et al. method (P4) were 0.896 ± 0.096, 1.385 ± 0.224, 187.207 ± 26.398, and 0.621 ± 0.098, respectively. Effect of sires was significant (P < 0.05) on P2 and P4 methods. Effect of genetic group on all four methods was non-significant. Period of calving had significant (P < 0.01) effect on persistency of milk yield (P2, P3, and P4 methods). Effect of season of calving on persistency of milk yield was found to be significant in all estimates obtained by the four methods. Summer and autumn calvers were most persistent whereas spring and winter calvers were least persistent for (P2, P3, and P4 methods). Persistency of milk yield was significantly (P < 0.05) affected by days to attain peak yield in P1 and P2 methods. Maximum persistency was obtained in animals attaining peak at 41-57days of lactation and minimum in < 41days for Mahadevan method and ratio method. The highest heritability of persistency and minimum value of standard error was estimated as 0.275 ± 0.11 for the Mahadevan method followed by the Prasad method (0.197 ± 0.10) by half sib correlation method. The maximum coefficient of variation which indicates available variability was estimated as 20.788% for persistency by the Mahadevan method followed by 18.969% for the Prasad method. The highest correlation was also observed between P1 and P3 methods by Spearman's and Pearson's correlation for least squares breeding value of the sires. On the basis of heritability, standard error of heritability, and coefficient of variation, it can be concluded that the Mahadevan method followed by the Prasad method suits best to our environment for animals in first lactation as well as they can be utilized for effective selection for higher persistency in crossbred animals of Punjab.

Genetic perspective of milk yield persistency in the first three lactations of Iranian buffaloes (Bubalus bubalis).

The objectives of this study were to estimate the genetic parameters and genetic trends for different measures of persistency (PM) for milk yield in Iranian buffaloes using a random regression test day model. Test day records of the first three lactations of buffaloes within 715 herds comprising 43 014, 38 941 and 33 937 records, respectively, were obtained from the Animal Breeding Center of Iran during 1992 to 2012. Legendre polynomial functions were chosen to fit the lactation curves in the framework of a random regression test day model for estimating (co)variance components. Three measures of persistency were modified based on the lactation curve conditions of buffaloes: (1) The average of estimated breeding values (EBVs) for test day milk yields from day 226 to day 270 as a deviation from the average of EBVs from day 44 to day 62 (PM1), (2) A summation of contribution for each day from day 53 to day 247 as a deviation from day 248 (PM2), (3) The difference between EBVs for day 257 and day 80 (PM3). The highest heritability estimates were observed for PM2 over the first three lactations (0·29, 0·80 and 0·42, respectively). Estimates of genetic correlations between persistency measures and milk yield varied from -0·48 to 0·29 (first lactation), from -0·12 to 0·48 (second lactation), and from -0·62 to 0·63 (third lactation). Estimate of genetic trend for first lactation PM2 was negative (-0·0088 ± 0·0043; P < 0·05). It is essential to include milk yield persistency in the breeding goal of Iranian buffaloes along with other important traits such as milk yield or reproductive traits.

Prediction of lactation persistency in crossbred cattle using genotype profile of lactation curve traits

The objective of the present study was to identify the best fit lactation model in relation to bovine leptin gene and to assess lactation persistency based on lactation curve traits in crossbred Karan Fires cattle. Incomplete gamma (Wood) function and exponential (Wilmink) function tests were used to describe the characteristics of lactation curve in first lactation. Woods model showed a comparatively better fit. Different types of lactation curves depicted by these cattle using data spread over a period of 15 years (1994 to 2009) were grouped into desired and nondesired type of lactation curve. Subsequently, genotype profiling was done using PCR-RFLP. A single nucleotide polymorphism identified in exon-2 region of bovine leptin gene, was associated with desired type of lactation curve and animals having TT genotype showed better persistency of milk yield. The results validated in test population had shown positive relationship between leptin genotypes and lactation curve traits. The inference from work has a potential application in breeding program of the country, where it may give support to existing expected producingability (EPA) based selection methodology followed for selection of dairy animals, by adding leptin genotype as one additional selection criterion for early selection in crossbred dairy bulls and cattle.

Evaluation of Different Measures of Milk Yield Persistency in Iranian Holstein Dairy Cows

Test-day lactation records of primiparous Holstein cows over an eleven-year period were evaluated for persistency and estimates of its heritability and correlation with other lactation traits computed. In this study, 435390 test day records of the first lactation Holstein cows that calved between 2001 and 2011 from 659 herds were analyzed using various procedures of SAS. Per1% (dividing total milk yield between 101-200 days by the yield of the first 100 days of lactation) measure was preferred in the selection of animals for milk yield persistency because of higher heritability (0.084 ± 0.009) and the lower phenotypic correlation with 305 days milk yield (0.424) compare to other persistency measures. The result showed that cows which calved during summer and autumn had slightly higher persistency in comparison to cows that calved in spring or winter. The persistency can be affected by the age at first calving, as cows that calved at a younger age had lower persistency.