Sire marbling score expected progeny difference and weaning weight maternal expected progeny difference associations with age at first calving and calving interval in Angus beef cattle.

Abstract

Field records from the American Angus Association were used to study the associations of sire marbling score EPD and sire weaning weight maternal (milk) EPD with age at first calving (AFC) and calving interval (CI). Cows were selected based on the accuracy of their sire's milk (> or =.7) or marbling (> or =.6) EPD. The data were screened using biological constraints, and regression models were used to identify records that were greater than 5 SD from the mean. The AFC was modeled for both milk and marbling data sets to account for effects of year, sire EPD, and their interaction. The CI was subdivided into first, second, and mature calving interval traits and modeled to account for state, year, calf sex, calf birth weight (BW), calf weaning weight (WW), sire EPD, and interactions of EPD with year and state. Derivative-free REML was used to estimate heritability and genetic correlations for AFC and CI. Sire milk EPD and marbling EPD were predictors of AFC (P < .001); however, pooled estimates were unreliable because of state x EPD interactions (P < .001). Increases in sire milk EPD resulted in reductions in AFC; however, there was no consistent pattern to effects of marbling EPD increases. Models accounted for < 8% of variation in AFC. Sire milk EPD was not a predictor of first, second, or mature CI (P > .1). Sire marbling score EPD was not a predictor of second, or mature CI (P > .1); however, it was associated (P = .059) with first CI, although regression estimates varied across states and prevented pooling. The BW, sex, and WW were predictors of CI (P < .001). Increases in BW resulted in longer mature CI, and mature CI decreased as WW increased. The AFC was heritable (.22), and CI traits had heritabilities ranging from .01 to .03. The AFC was genetically correlated with first CI (-.6) and mature CI (-.93). Genetic correlations between CI traits were uninterpretable because of low additive genetic variances. In conclusion, sire marbling score and milk EPD do not seem to be reliable predictors of AFC or CI. The BW and WW have significant but small effects on AFC and CI. Selection for AFC is possible, but earlier calving heifers may have longer calving intervals.

Importance of dam BW change and calf birth weight in double-muscled Belgian Blue cattle and its relationship with parity and calving interval

“…Factors affecting CI The mean CI of 404 days observed for DMBB cows in this study was considerably longer than reported for most other beef breeds (Osoro and Wright, 1992;Frazier et al, 1999; Fiems and Ampe Pilarczyk and Wójcik, 2008). Reasons for the reduced reproductive performance are related to the double-muscling phenomenon (Fiems, 2012).…”

“…Hanzen et al (1994) reported an average CI of 435 days in suckled DMBB cows compared with 364 days for Blue-Grey cows (Osoro and Wright, 1992), 370 days for Angus cows (Frazier et al, 1999), 377 days for Simmental cows, 387 days for Salers cows, 381 days for Limousin cows and 393 days for Hereford cows (Pilarczyk and Wójcik, 2008). It averaged 364 days for Charolais and Limousin multiparous cows, and 385 and 389 days, respectively, for Charolais and Limousin primiparous cows (Agabriel et al, 1992).…”

Heredabilidad de características reproductivas de vacas Indubrasil.

“…Por el contrario, Frazier et al (1999) con ganado Angus, Oyama et al (2002) con ganado Japonés Negro y Azevêdo et al (2006b) con ganado Nelore encontraron que intervalo entre partos es escasamente heredable con valores de 0,03, 0,05 y 0,05, respectivamente. Se ha reportado que bajos estimadores de heredabilidad para intervalo entre partos se pueden deber a: 1) la poca disponibilidad de animales en la estimación, 2) la fuerte influencia ambiental sobre la característica, 3) la necesidad de ajustar mejor los efectos fijos, y 4) al uso de modelos que no pueden explicar adecuadamente la estructura de la población evaluada (Goyache y Gutiérrez 2001).…”

A deterministic simulation study of embryo marker-assisted selection for age at first calving in Nellore (Bos indicus) beef cattle

“…A lower AFC has a positive impact on both economic and breeding aspects of cattle production, such as reduced costs of raising heifers and reduced female generation interval. Despite the importance of AFC, many breeding programs do not include this trait in the breeding goal because of its low heritability, sex-limited expression and antagonistic relationships with production traits (Frazier et al, 1999;Nogueira, 2004, Forni andAlbuquerque, 2005;Pereira et al, 2006).…”