Factors Affecting Days Open, Gestation Length, and Calving Interval in Florida Dairy Cattle

Abstract

Effects of several factors on reproductive performance were evaluated. Mean performance and number of observations were for days from parturition to first service, 93 and 7730; days from first to successful service, 35 and 11,751; days open, 123 and 8571; gestation length, 280 and 13,612; and calving interval, 400 and 8524. Data covered 52 yr during which no detectable trends in calving interval occurred; other variables changed slightly. Jerseys had 8 fewer d from parturition to first service, 16 fewer d from first service to conception, 8 fewer d open, and 8-d shorter calving intervals than did Guernseys and Holsteins, which did not differ. Cows freshening in warm rather than cool weather suffered by 7, 7, 12, and 13 d for these variables. Repeatabilities ranged from .05 to .12; heritabilities were .05 and .06. Nonmaternal estimate of heritability of gestation length was .22. Phenotypic and genetic correlations between days from parturition to first service and calving interval were .48 and .87; for days open and calving interval, they were .97 and .96. Although days from first to successful service were essentially uncorrelated with days open and calving interval phenotypically (.05), genetic correlations were greater than 1.0 and estimated as unity. Results show no discrepancy between estimates for measures of reproductive performance in a subtropical environment and numerous studies in temperate areas. Large studies from subtropical areas are sparse; essentially none concerns long-term trends.

Fatores de variação e parâmetros genéticos dos períodos de serviço e seco em bovinos da raça Holandês no estado de Minas Gerais

“…No entanto, melhorias no manejo pré e pós-parto, que permitam melhor condição corporal no pré-parto, acompanhada de assistência sanitária mais criteriosa, bom manejo nutricional, apurada detecção de cio e, finalmente, uso correto das técnicas de inseminação, podem conjuntamente contribuir para redução do PSER. Na literatura, em sua maioria, as médias de PSER são muito variáveis com valores médios superiores 1008 PEREIRA et al (DIAS et al, 1985;SILVA et al, 1992;CAMPOS et al, 1994;CASTRO et al, 1995;e MAKUZA e McDANIEL, 1996) ou inferiores (RIBAS et al, 1995) ao estimado no presente trabalho.…”

“…As estimativas de herdabilidade (h 2 ) para PSER obtidas por análise univariada e bivariada (0,052 e 0,027, respectivamente) são baixas, sendo semelhantes às obtidas por RAHEJA et al (1989), HAYES et al (1992, SILVA et al (1992) e MOORE et al (1992) e, também, por MARTI e FUNK (1994) e VALENTE et al (1995, pelo método DFREML. As estimativas para PSER sugerem que a variância genética aditiva para esta característica é pequena, indicando que a sua expressão pode ser mais influenciada pela atuação de genes dominantes ou epistáticos ou, ainda, de fatores fisiológicos e de ambiente.…”

“…As estimativas de repetibilidade para o PSER, pelas análises uni e bivariadas, foram de 0,06. Valores superiores haviam sido obtidos por SILVA et al (1992). Estas estimativas inferiores devemse à baixa variância genética aditiva e do efeito permanente do animal.…”

Evaluation of gestation length and birth weight of offspring of Polish native cattle breeds in context of estimating genetic parameters

“…King et al (1985) found out that as far (1998) and McClintock et al (2003) proved that in summer calves were born after shorter gestation. However, earlier research done by Silva et al (1992) showed that temperature and seasonal feedstuff did not have a significant effect on gestation length. On the other hand, we found out that gestation length of cows calving in summer was highly significantly longer than of those calving in winter.…”

Parámetros Reproductivos Del Ganado Vacuno en La Cuenca Lechera De Lima

“…El IPPS es influenciado por la condición corporal (CC), el balance energético negativo (BEN), la estación del parto y el volumen de producción láctea (Inostroza y Sepúlveda, 1999; Echevarría et al, 2002). En casos de IPPS relativamente largos como el del presente estudio, extensos periodos de anestro postparto, problemas de expresión de signos de celo, fallas en la detección de celos, y deficiencia en el manejo de los registros pueden estar ocurriendo (Silva et al, 1992). Sepúlveda (2001) indica como una meta plausible que el 85% de las vacas deben ser observadas en celo dentro de los 60 días del parto, de lo contrario cabe pensar en ausencia de actividad cíclica ovárica.…”