Rearing strategy and optimizing first-calving targets in dairy heifers: a review

Experiment was conducted to evaluate the effect of weaning age on growth performance, feed intake, feed efficiency (FE) and blood metabolites in Nili-Ravi male buffalo (Bubalus bubalis) calves. Twenty-four male buffalo calves were assigned to one of the three treatment groups: continuous milk feeding (CMF), limited milk feeding (LMF) and early weaning (EW), and weaned off milk at 12, 10 and 8 weeks of age, respectively. For the first 3 days after birth, calves in all three treatments were fed colostrum, and were then moved to individual milk feeding at 10% of BW for the next 6 weeks. Thereafter, the provision of milk to the CMF group was gradually tapered to zero through week 12, using week 6 intakes as a base. The LMF calves were fed milk at 7.5%, 5.0%, 3.5%, and 1.5% of BW during weeks 7 to 10, respectively. Lastly, calves in the EW group were fed milk at 5.0% and 2.5% of BW at weeks 7 and 8, respectively. Calf starter (CS) feed was also provided ad libitum from weeks 2 to 12 and individual intakes were recorded on a daily basis. Blood samples were taken from weeks 6 to 12, on a weekly basis; whereas, the BW, heart girth, withers height and hip width were measured at the start of experiment and later on a weekly basis. Weight gain, average daily gain, and body measurements were the same across all three groups. Milk intake was lower ( P , 0.05), whereas CS intake was greater (P , 0.05) in the EW calves compared with the other treatment groups. Dry matter intake was greater (P , 0.05) in the EW and LMF calves compared with the CMF calves. The FE was greater ( P , 0.05) in the CMF calves compared with the LMF and EW treatment groups. Blood glucose concentration was similar among the treatments; however, blood urea nitrogen was greater ( P , 0.05) in the EW calves compared with the CMF and LMF groups. Plasma concentration of non-esterified fatty acids was higher (P , 0.05) in the EW calves compared with the CMF calves. In light of these results, it is evident that buffalo calves can be successfully weaned as early as 8 weeks of age without negatively affecting their growth performance.

Section: Discussionmentioning

confidence: 99%

Influence of weaning regimen on intake, growth characteristics and plasma blood metabolites in male buffalo calves

Rashid

Pasha

Jabbar

et al. 2013

“…No adverse effect of increasing BW (BW gain) on production potential was evident in the current study. The negative effects of feeding intensity pre-puberty on milk yield potential because of mechanisms responsible for reduced mammary development have been widely documented (Le Cozler et al, 2008). However, this effect is less certain under grass-based systems (Macdonald et al, 2005), likely because of the less intensive nature of the rearing process.…”

Section: Discussionmentioning

confidence: 99%

“…During this visit, heifers were weighed, body condition scored, blood samples were collected and transrectal ultrasonography was conducted. As cows, they were weighed and body condition scored once during May and June 2006, 2007and 2008. These visits coincided with the breeding period, which in Irish seasonal calving herds typically begins in late April (Buckley et al, 2003 …”

Section: Methodsmentioning

confidence: 99%

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

Archbold

Shalloo

Kennedy

et al. 2012

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.

“…This requires the heifer to have an adequate growth rate to ensure an appropriate BW at calving. AFC, growth rate and BW at first calving are all correlated, making their effects on future performance hard to separate (Le Cozler et al, 2008). Heifer fertility is a critical component of AFC.…”

Section: Introductionmentioning

confidence: 99%

Heifer fertility and carry over consequences for life time production in dairy and beef cattle

Wathes

Pollott

Johnson

et al. 2014

141

116

The rearing period has a key influence on the later performance of cattle, affecting future fertility and longevity. Producers usually aim to breed replacement heifers by 15 months to calve at 24 months. An age at first calving (AFC) close to 2 years (23 to 25 months) is optimum for economic performance as it minimises the non-productive period and maintains a seasonal calving pattern. This is rarely achieved in either dairy or beef herds, with average AFC for dairy herds usually between 26 and 30 months. Maintaining a low AFC requires good heifer management with adequate growth to ensure an appropriate BW and frame size at calving. Puberty should occur at least 6 weeks before the target breeding age to enable animals to undergo oestrous cycles before mating. Cattle reach puberty at a fairly consistent, but breed-dependent, proportion of mature BW. Heifer fertility is a critical component of AFC. In US Holsteins the conception rate peaked at 57% at 15 to 16 months, declining in older heifers. Wide variations in growth rates on the same farm often lead to some animals having delayed first breeding and/or conception. Oestrous synchronisation regimes and sexed semen can both be used but unless heifers have been previously well-managed the success rates may be unacceptably low. Altering the nutritional input above or below those needed for maintenance at any stage from birth to first calving clearly alters the average daily gain (ADG) in weight. In general an ADG of around 0.75 kg/day seems optimal for dairy heifers, with lower rates delaying puberty and AFC. There is some scope to vary ADG at different ages providing animals reach an adequate size by calving. Major periods of nutritional deficiency and/or severe calfhood disease will, however, compromise development with long-term adverse consequences. Infectious disease can also cause pregnancy loss/abortion. First lactation milk yield may be slightly lower in younger calving cows but lifetime production is higher as such animals usually have good fertility and survive longer. There is now extensive evidence that as long as the AFC is > 23 months then future performance is not adversely influenced. On the other hand, delayed first calving > 30 months is associated with poor survival. Underfeeding of young heifers reduces their milk production potential and is a greater problem than overfeeding. Farmers are more likely to meet the optimum AFC target of 23 to 25 months if they monitor growth rates and adjust feed accordingly.