Genetic Parameters and Trends of Milk, Fat, Days Open, and Body Weight After Calving in North Carolina Experimental Herds

Abstract

The main objective of this study was to estimate genetic trends for 3.7% FCM, fat yield, days open, and predicted body weight after calving in six experimental dairy herds owned by the State Farm Division of the North Carolina Department of Agriculture. Body weights were predicted from heart girths measured at or before the first test day after calving. Data analyzed were 23,052 records from 8575 cows, daughters of 681 bulls. Heritabilities and breeding values were estimated using the multiple-trait, derivative-free REML programs and a single-trait repeatability model. Breeding values of cows were averaged by and regressed on birth year to estimate genetic trends. Genetic correlations between traits were estimated by correlating breeding values. Estimates of heritability were 0.25 for 3.7% FCM, 0.28 for fat yield, 0.03 for days open, and 0.17 for predicted body weight. Unfavorable genetic relationships were found between yields and days open and between yields and body weight. Genetically, cows that were heavier after calving produced less milk and fat but conceived earlier than smaller cows. Genetic changes in yields and days open were greater for cows born after 1970, but the greatest genetic changes were after 1980 (FCM, 94.7 kg/yr; fat yield, 3.46 kg/yr; days open, 1.1 d/yr). Breeding values for body weight increased for cows born from 1950 to 1970, decreased until 1980, and increased for later parities. The results of our study suggest that AI organizations may need to include fertility traits in progeny testing and relax the emphasis on increased body weight.

Analysis of culling records and estimation of genetic parameters for longevity and some production traits in Holstein dairy cattle

“…The estimated heritability for fat yield (0.16) was lower than that of milk yield (0.25). These results were in agreement with Abdallah and McDaniel (2000) and Makgahlela et al (2008). The estimates of heritability for herd life and length of productive life were 0.11 and 0.09, respectively, which were similar to the reports of Strandberg and Solkner (1996).…”

Caracterização fenotípica e genética da produção de leite e do intervalo entre partos em bubalinos da raça Murrah

“…A herdabilidade para o intervalo entre partos foi de 0,02, valor em concordância com aqueles normalmente relatados na literatura sobre bovinos de leite, os quais são baixos (Abdallah & McDaniel, 2000;Silva et al, 2001). Lôbo et al (2000) revisaram informações de 52 artigos com bovinos leiteiros em regiões tropicais e relataram herdabilidade média de 0,11 para essa característica.…”

“…A magnitude da repetibilidade indica a possibilidade de se utilizar as primeiras produções das búfalas como indicativo de sua produção futura, e de escolher, assim, as fêmeas que continuarão no rebanho. A repetibilidade para o intervalo entre partos foi 0,06, valor inferior ao relatado em búfalos (0,14), por Aziz et al (2001), e em bovinos leiteiros, por Abdallah & McDaniel (2000), Pereira et al (2000) e Silva et al (2001).…”

“…Zambianchi et al (1999) relataram correlação genética positiva, porém, indesejável entre produção de leite e intervalo entre partos. Abdallah & McDaniel (2000) frisaram que nos vários trabalhos disponíveis na literatura com bovinos, em que foi avaliada a tendência genética, foram analisados basicamente os registros de produção de leite e de seus componentes, e não foram consideradas as possíveis alterações nas características reprodutivas, em decorrência da seleção direta, ou como resposta correlacionada da seleção para as características de produção.…”

Association of the occurrence of some diseases with reproductive performance and milk production of dairy herds in southern Brazil

“…That may be attributed to the occurrence of negative energy balance during the post-partum period, which has negative effects on the resumption of ovarian cyclicity (Reist et al, 2003). Thus, milk production and reproductive efficiency are negatively associated (Abdallah & McDaniel, 2000), indicating that genetic improvement prioritized milk production instead of fertility traits (Dobson et al, 2007).…”