Influence of age, body weight and body condition score before mating start date on the pubertal rate of maiden Holstein–Friesian heifers and implications for subsequent cow performance and profitability

Abstract

The aim of this study was to assess the influence of age, body weight (BW) and body condition score (BCS) of maiden Holstein-Friesian heifers before mating start date (MSD) on the rate of puberty, subsequent production and longevity and their implications with regard to farm profitability. Data were available on 871 Holstein-Friesian heifers from 48 herds. BW was recorded electronically and BCS was recorded by a single operator on a scale of 1 to 5. Heifer age was calculated as the number of days from birth to the day of visit. All of the independent variables of interest were grouped into three or four categories. Three age categories (thirtiles), four BW categories (quartiles) and four BCS categories (<2.75, 3.00, 3.25 and >3.50) were formed. Heifers with an identifiable corpus lutuem (CL) in the presence or absence of large follicles and peri-ovulatory signs and with a plasma progesterone (P4) concentration >1 ng/ml were classified as pubertal. In addition, heifers without an identifiable CL in the presence or absence of large follicles and peri-ovulatory signs but with a P4 concentration >1 ng/ml were also classified as pubertal. Age, BW and BCS at MSD were all found to be significantly associated with pubertal rate (P , 0.05). Age was shown to have no practical implications on subsequent cow performance. BW at MSD was favourably associated with subsequent calving date (P , 0.05), subsequent cow BW (P , 0.001) and potential (305 days) milk fat plus protein yield (P , 0.001). BCS at MSD was found to be favourably associated with milk fat plus protein yield potential (P , 0.05) and BCS (P , 0.001) during lactation. The economic analysis undertaken indicated that larger, well-grown heifers will be more profitable because of superior production potential, all else being equal. However, because of the finding of poorer reproductive efficiency in heifers grown to more than 343 kg at MSD, heifers at ,330 kg at MSD are deemed optimal. This will correspond to mature cow BW of ,550 kg.

Ultrasonographic reproductive tract measures and pelvis measures as predictors of pregnancy failure and anestrus in restricted bred beef heifers

“…Although not validated against estrus or pregnancy outcomes during the breeding period following examination, Archbold et al [6] estimated the sensitivity of ultrasonography to determine pubertal status to be reduced during pro-estrus and metestrus, due to the relatively poor ability to visualise the regressing corpus albicans and the corpus haemoragicum respectively. We therefore assume that the reason why the absence of a follicle ≥13 mm remained an independent predictor in our models was either that some heifers that were pubertal at the time of examination had their first estrus in the few days after the examination, or that in postpubertal heifers a CL was not detected due to stage of the estrus cycle.…”

“…Reproductive tract score (RTS) predicts anestrus and pregnancy failure in heifers independently of age, body weight (BW) and body condition score (BCS), and is a valid selection tool to enhance reproductive performance of herds [3][4][5][6][7]. However, estrus cycle stage and proportion of heifers in anestrus affect the accuracy of RTS, the complexity of the RTS system affects its repeatability, and other tests with potential to improve RTS are available [5,[7][8][9].…”

Applications and cost benefits of sexed semen in pasture-based dairy production systems

“…An efficient heifer rearing system is essential to meet these targets and ensure that replacement heifers maximise their potential as lactating animals. Archbold et al (2012) demonstrated that larger, well grown heifers had greater pubertal rates at mating start date (MSD), and were more profitable over their lifetime due to superior milk production and greater longevity.…”

“…These heifer calves will be closely grouped in terms of age, and it would therefore be easier to manage them as one group to meet the optimal target of 60% of mature BW at MSD (Archbold et al, 2012).…”

Nutritional management to optimize fertility of dairy cows in pasture-based systems

“…The effects of inadequate nutrition in cattle include delayed puberty Archbold et al, 2012), prolonged postpartum anovulation (Rhodes et al, 2003), reduced body condition score (BCS) , and poor submission and conception rates (Buckley et al, 2003). Dairy production systems based on grazed pasture are primarily located in countries where environmental conditions support long growing seasons.…”