Effect of restricting silage feeding prepartum on time of calving, dystocia and stillbirth in Holstein-Friesian cows

A study was carried out to investigate the effect of restricting silage feeding on time of calving and calving performance in Holstein-Friesian cows. In the treatment group (n = 1,248 cows, 12 herds) silage feeding commenced in the evening (17:00 to 20:00 h), after a period of restricted access (2 to 10 h) while in the control group ad-libitum access to silage was provided over the 24 h period (n = 1,193 cows, 12 herds). Daytime and nighttime calvings were defined as calvings occurring between the hours of 06:30 and 00:29 and between 00:30 and 06:29, respectively. Restricting access to silage resulted in less calvings at night compared to cows with ad-libitum access to silage (18 vs 22%, P < 0.05). Cows with restricted access to silage had a higher percentage of difficult calvings (11 vs 7%, P < 0.001) and stillbirths (7 vs 5%, P < 0.05) compared to cows in the control group. The percentage of calvings at night was lower (13%) when access to silage was restricted for 10 h compared to 2, 4 or 6 h (22, 18, 25%, respectively) (P < 0.001). Calf sire breed, calf gender or cow parity did not influence time of calving. In conclusion, offering silage to pregnant Holstein-Friesian cows in the evening, after a period of restricted access, reduced the incidence of nighttime calvings, but increased the incidence of dystocia and stillbirth

Statistical practices of educational researchers: An analysis of their ANOVA, MANOVA, and ANCOVA analyses

Articles published in several prominent educational journals were examined to investigate the use of data-analysis tools by researchers in four research paradigms: between-subjects univariate designs, between-subjects multivariate designs, repeated measures designs, and covariance designs. In addition to examining specific details pertaining to the research design (e.g., sample size, group size equality/inequality) and methods employed for data analysis, we also catalogued whether: (a) validity assumptions were examined, (b) effect size indices were reported, (c) sample sizes were selected based on power considerations, and (d) appropriate textbooks and/or articles were cited to communicate the nature of the analyses that were performed. Our analyses imply that researchers rarely verify that validity assumptions are satisfied and accordingly typically use analyses that are nonrobust to assumption violations. In addition, researchers rarely report effect size statistics, nor do they routinely perform power analyses to determine sample size requirements. We offer many recommendations to rectify these shortcomings.Social Sciences and Humanities Research Counci

Impacts of alternative replacement breeding systems on biological and economic performance in beef suckler production using a herd level bio-economic model

AbstractA deterministic bio-economic model was used to investigate the impact of different heifer replacement breeding systems for beef suckler cow production in different environments. It was shown that measures of cow efficiency were highly correlated with profitability in suckled calf production. However, where significant genotype differences exist in final output value due to issues of carcass quality, then more complete characterization of system profitability is recommended. In systems utilizing a terminal sire mating policy for all matings in excess of replacement heifer requirements the proportion of terminal sire matings made are affected by female fertility. Reduced cow fertility combined with late attainment of puberty in heifers and low heifer fertility has a substantial negative effect on the proportion of terminal sire matings made. This illustrates an aspect of production that can be improved by the use of crossbreeding to exploit heterosis in reproductive traits. The time frame of impacts of the different systems was seen to vary. Grading up to a pure breed allowed exploitation of heterosis in the early years of the transition leading to a boost in profitability but this boost was lost as the herd became purebred. Composite and rotational crossing systems were seen to create a steady rise in financial margin to the point where they became stable in breed proportion and heterosis. The effect of cow size was evaluated in three different environments, representing UK lowland, upland and hill. It was found that small cows became more profitable in relation to large cows as food resources became more limiting. In a non-limiting environment large cows were more profitable than small cows.</jats:p