Genetic analysis of fertility traits of Holstein dairy cattle in warm and temperate climate / Análise genética de traços de fertilidade em vacas leiteiras Holstein em climas quentes e temperados

The edited data set for the estimation of heritability, genetic and phenotypic correlations of fertility traits contained up to 23,402 records from 10,894 cows calved between 2001 and 2015. Heritability estimates for success in first service (FS), gestation length (GL), number of inseminations (NI), insemination outcome (IO), calving interval (CI), calving birth weight (CBW) and days open (DO) were low and ranged between 0.016 (DO) and 0.123 (GL). Repeatability of fertility traits was estimated to vary from 0.021 (FS) to 0.411 (IO). The genetic correlations between DO × CI, DO × NI and CI × NI were positive and nearly perfect (0.98, 0.88 and 0.88, respectively), while those between DO × IO and CI × IO were negative (-0.98 and -1, respectively). Further, the phenotypic correlations between DO × CI, DO × NI, CI × NI, CBW × IO and SF × IO were 0.99, 0.83, 0.83, 0.99 and 1, respectively, while those between DO × IO, CI × IO, GL × IO and NI × IO were -0.99, -0.99, -0.99 and -1, respectively. Overall genetic parameters imply a good practical management in heat stress conditions will be essential for improving fertility efficiency.(AU)

Os dados editados para definir a estimativa de herdabilidade, correlações genéticas e fenotípicas de características de fertilidade continham até 23,402 registros a partir de 10,894 vacas paridas entre 2001 e 2015. As estimativas de herdabilidade para o sucesso no primeiro serviço (SF), duração da gestação (GL), número de inseminações (NI), resultado de inseminação (IO), intervalo entre partos (CI), peso ao nascer (CBW) e dias abertos (DO) foram baixas e variaram entre 0,016 (DO) e 0,123 (GL). A repetitividade das características de fertilidade foi estimada e variou entre 0,021 (SF) e 0,411 (IO). A correlação genética entre DO × CI, DO × NI e CI × NI foi positiva e quase perfeita (0,98, 0,88 e 0,88, respectivamente), enquanto que aquela entre DO × IO e CI × IO foi negativa (-0,98 e -1, respectivamente). A correlação fenotípica entre DO × CI, DO × NI, CI × NI, CBW × IO e SF × IO foi 0,99, 0,83, 0,83, 0,99 e 1, respectivamente, enquanto aquela entre DO × IO, CI × IO, GL × IO e NI × IO foi -0,99, -0,99, -0,99 e -1, respectivamente. Os parâmetros genéticos constatados implicam que será essencial uma gestão bem prática na condição de estresse por calor para melhoria da eficiência da fertilidade.(AU)

Genetic and phenotypic trends of fertility traits for Holstein dairy population in warm and temperate climate

The main objective of this study was to investigate genetic and phenotypic trends for fertility traits in Holstein dairy population under warm and temperate climate. Fertility traits were: success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open. The edited data set included up to 23,402 records from 9,486 cows. The mean and standard deviation for fertility traits were 0.32 ± 0.003, 278.2 ± 5.58, 2.73 ± 1.94,0.31 ± 0.001, 415.99 ± 79.62, 40.4 ± 6.08 and 140.36 ± 76.16 for success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open, respectively. In general, there were decreasing genetic trends for all traits over the years. On the other hand, there were decreasing phenotypic trend for days open, calving interval, gestation length, number of inseminations and calving birth weight, but estimates of phenotypic trends were positive for success in first service and insemination outcome over the years. It was concluded decreased trend for days open, calving interval, gestation length, number of inseminations and calving birth weight and increased trend for success in first service and insemination outcome traits over time indicated that Holstein dairy producers in warm and temperate climate were successful in managing and improving in nutrition during 1999 to 2013> (AU)

Genetic analysis of fertility traits of Holstein dairy cattle in warm and temperate climate / Análise genética de traços de fertilidade em vacas leiteiras Holstein em climas quentes e temperados

The edited data set for the estimation of heritability, genetic and phenotypic correlations of fertility traits contained up to 23,402 records from 10,894 cows calved between 2001 and 2015. Heritability estimates for success in first service (FS), gestation length (GL), number of inseminations (NI), insemination outcome (IO), calving interval (CI), calving birth weight (CBW) and days open (DO) were low and ranged between 0.016 (DO) and 0.123 (GL). Repeatability of fertility traits was estimated to vary from 0.021 (FS) to 0.411 (IO). The genetic correlations between DO × CI, DO × NI and CI × NI were positive and nearly perfect (0.98, 0.88 and 0.88, respectively), while those between DO × IO and CI × IO were negative (-0.98 and -1, respectively). Further, the phenotypic correlations between DO × CI, DO × NI, CI × NI, CBW × IO and SF × IO were 0.99, 0.83, 0.83, 0.99 and 1, respectively, while those between DO × IO, CI × IO, GL × IO and NI × IO were -0.99, -0.99, -0.99 and -1, respectively. Overall genetic parameters imply a good practical management in heat stress conditions will be essential for improving fertility efficiency.

Os dados editados para definir a estimativa de herdabilidade, correlações genéticas e fenotípicas de características de fertilidade continham até 23,402 registros a partir de 10,894 vacas paridas entre 2001 e 2015. As estimativas de herdabilidade para o sucesso no primeiro serviço (SF), duração da gestação (GL), número de inseminações (NI), resultado de inseminação (IO), intervalo entre partos (CI), peso ao nascer (CBW) e dias abertos (DO) foram baixas e variaram entre 0,016 (DO) e 0,123 (GL). A repetitividade das características de fertilidade foi estimada e variou entre 0,021 (SF) e 0,411 (IO). A correlação genética entre DO × CI, DO × NI e CI × NI foi positiva e quase perfeita (0,98, 0,88 e 0,88, respectivamente), enquanto que aquela entre DO × IO e CI × IO foi negativa (-0,98 e -1, respectivamente). A correlação fenotípica entre DO × CI, DO × NI, CI × NI, CBW × IO e SF × IO foi 0,99, 0,83, 0,83, 0,99 e 1, respectivamente, enquanto aquela entre DO × IO, CI × IO, GL × IO e NI × IO foi -0,99, -0,99, -0,99 e -1, respectivamente. Os parâmetros genéticos constatados implicam que será essencial uma gestão bem prática na condição de estresse por calor para melhoria da eficiência da fertilidade.

Genetic and phenotypic trends of fertility traits for Holstein dairy population in warm and temperate climate

The main objective of this study was to investigate genetic and phenotypic trends for fertility traits in Holstein dairy population under warm and temperate climate. Fertility traits were: success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open. The edited data set included up to 23,402 records from 9,486 cows. The mean and standard deviation for fertility traits were 0.32 ± 0.003, 278.2 ± 5.58, 2.73 ± 1.94,0.31 ± 0.001, 415.99 ± 79.62, 40.4 ± 6.08 and 140.36 ± 76.16 for success in first service, gestation length, number of inseminations, insemination outcome, calving interval, calving birth weight and days open, respectively. In general, there were decreasing genetic trends for all traits over the years. On the other hand, there were decreasing phenotypic trend for days open, calving interval, gestation length, number of inseminations and calving birth weight, but estimates of phenotypic trends were positive for success in first service and insemination outcome over the years. It was concluded decreased trend for days open, calving interval, gestation length, number of inseminations and calving birth weight and increased trend for success in first service and insemination outcome traits over time indicated that Holstein dairy producers in warm and temperate climate were successful in managing and improving in nutrition during 1999 to 2013>

Effect of calf birth weight on milk production of Holstein dairy cattle in desert climate

The hypothesis in this study was that calf birth weight (CBW) would effect on cow"s milk production. Data were collected from two commercial dairy milking 15,000 Holsteins in central region of Iran from 2006 to 2012. Animals were enrolled at parturition until 7,737 calvings were available for analysis. Data consisted of on-farm measurements of calf birth weight and milk production, and data were analyzed using a multivariable regression model. Independent variables were parity, herd-year-season, calving interval, calving age, retained placenta, days open, dry period length, days in milk, linear and quadratic CBW. The mean CBW was 40.84 ± 4.9 kg (SD) with a range of 20 to 60 kg. There was a trend for milk305 based on calf birth weight, i.e., the amount of milk305 of dam was significantly dependent on that weight of calf was born (P 0.01). Cows with CBW between 20 and 25 kg had the lowest of milk production. By increasing of CBW range up to 40 and 45 kg, the trend of milk production increased and then decreasing trend observed. In conclusion, calf birth weight could be considered as an important trait in dairy cattle breeding programs.

Effect of calf birth weight on milk production of Holstein dairy cattle in desert climate

The hypothesis in this study was that calf birth weight (CBW) would effect on cow"s milk production. Data were collected from two commercial dairy milking 15,000 Holsteins in central region of Iran from 2006 to 2012. Animals were enrolled at parturition until 7,737 calvings were available for analysis. Data consisted of on-farm measurements of calf birth weight and milk production, and data were analyzed using a multivariable regression model. Independent variables were parity, herd-year-season, calving interval, calving age, retained placenta, days open, dry period length, days in milk, linear and quadratic CBW. The mean CBW was 40.84 ± 4.9 kg (SD) with a range of 20 to 60 kg. There was a trend for milk305 based on calf birth weight, i.e., the amount of milk305 of dam was significantly dependent on that weight of calf was born (P 0.01). Cows with CBW between 20 and 25 kg had the lowest of milk production. By increasing of CBW range up to 40 and 45 kg, the trend of milk production increased and then decreasing trend observed. In conclusion, calf birth weight could be considered as an important trait in dairy cattle breeding programs.(AU)