Well-grown dairy calves and heifers play an important role in the future success of all dairy farms, and the phase of growth occurring between birth and weaning may have major economic importance. Clearly, improvements in the first-lactation milk production would be the ultimate return for a greater investment in early calf rearing programs. Recent research has demonstrated that greater pre-weaning average daily gain (ADG) can have a positive effect on the future production (Moallem et al. Reference Moallem, Werner, Lehrer, Zachut, Liveshitz, Yakoby and Shamay2010; Soberon et al. Reference Soberon, Raffrenato, Everett and Van Amburgh2012; Soberon & van Amburgh, Reference Soberon and Van Amburgh2013), mainly due to higher growth rate during early life. However, not all studies agree and some have found there to be no effect of increasing whole milk or milk replacer intake during the neonatal period on first-lactation performance (Morrison et al. Reference Morrison, Wicks, Fallon, Twigge, Dawson, Wylie and Carson2009; Raeth-Knight et al. Reference Raeth-Knight, Chester-Jones, Hayes, Linn, Larson and Ziegler2009; Kiezebrink et al. Reference Kiezebrink, Edwards, Wright, Cant and Osborne2015). These studies did have a few issues which should be considered, for instance, Kiezebrink et al. (Reference Kiezebrink, Edwards, Wright, Cant and Osborne2015) housed the milk-reared calves in environmentally controlled conditions, which is different from common on-farm conditions. These discrepancies call for more research in this area, particularly with the use of bigger data sets, which was the first objective of this research. In addition, there has been a positive correlation found between dam parity and calf birth weight (Elzo et al. Reference Elzo, Quaas and Pollak1987), which can affect ADG (Gregory et al. Reference Gregory, Cundiff, Smith, Laster and Fitzhugh1978). To our knowledge, nobody has evaluated this parameter in Holstein cows; therefore, the second objective of this study was to determine the effect of dam parity on future milk yield of the progeny.
Material and methods
Animal and experimental design
Growth and production parameters of 332 Holstein calves born during June to November 2012 were collected from a commercial dairy farm that had 3000 lactating cows (Magsal, Qazvin, Iran). This farm is located in a tropical area (longitude 50·31°E and latitude 36·07°N) where average daily milk production was around 37·5 kg per head. Thirty-five Holstein Friesian first lactation heifers and two hundred and ninety-seven multiparous cows were included in the dataset. All calves were managed similarly and fed whole milk, making it possible to detect within-herd variations related to ADG and first lactation performance.
All the calves were separated from their dam within 2 h of birth; the animals were fed 2.5.l of colostrum at each of the first 2 feedings (i.e. within 1·5 h after birth and in 12 h after the first feeding). Colostrum feeding was continued for the first 2 d of life. Calves were fed 4 l of whole milk in 2 separate feeds at 0800 and 1600 h, 4 l per day from 4 to 20 d of age, 5 l per day from 20 to 50 d of age, 2 l per day from 50 to 60 d of age, followed by milk being fed 1 l per day fed in one meal daily from 60 to 65 d of age in order to facilitate weaning. All calves were dehorned at 7 to 14 d of age using dehorning paste. Calves had unlimited access to water from day 3 onward. After weaning they were kept in groups of 12 calves per pens for 2 to 3 weeks, after which they were moved into groups of 24 calves per pen. At 3 of month of age onwards they all were kept in groups containing 80 calves per pen. All calves were offered cereal based starter from 3 d until 40 d of age, followed by which they were fed a mixed ration containing 10% alfalfa hay and 90% cereal based starter through until they were 3 months of age. Details of the diet are presented in online Supplementary Table S1.
Birth weight, weaning weight, hip height at weaning, age at weaning and age at calving were recorded for each calf. The ADG was calculated as: (weaning weight – birth weight)/days in period. Heifers were bred according to their body weight (BW; at least 360 kg) and hip height (130 cm) at 13 to 15 months of age and following. After calving, milk yield was recorded monthly. They were milked 3 times a day at 0600, 1400 and 2200. Milk fat and protein contents were analysed by CombiFoss 5000 (Foss Electric, Hillerød, Denmark). Actual 305-d milk yield as well as milk fat and protein yield were calculated from available data.
Statistical analysis
All data related to birth BW, weaning BW, age and height at weaning, pre-weaning ADG, age at calving, 305-d milk yield and milk fat and protein yield were analysed with the dam parity as independent variable in the model and data was analysed using MIXED procedures in SAS 9.4 (SAS Institute Inc., Cary, NC). To realise whether there is any relationship between early life performance and future production, regression of birth weight, weaning BW, age and height at weaning, pre-weaning ADG, age at calving and dam parity on 305-d milk yield was generated using PROC REG. Data were reported as least square means and were considered significant if P < 0·05.
Results and discussion
The data on birth weight, pre-weaning ADG, hip height at weaning, age at first calving and 305-d milk yield (Table 1) was analysed. The average birth BW was 37·46 ± 4·97 kg, with a range from 21 to 55 kg. As expected, when mean birth BW was considered separately for primiparous and multiparous cows, the heifer calves from cows were 2·5 kg heavier than progeny from primiparous animals (35·31 vs 37·71 kg; P < 0·007). Across the whole dataset, mean ADG was 566 g/d with a range of 269 to 1016. This range of ADG was narrower than reported by Soberon et al. (Reference Soberon, Raffrenato, Everett and Van Amburgh2012) and greater than reported by Yaylak et al. (Reference Yaylak, Orhan and Daşkaya2015). Both of these authors presented data obtained across several years. We did not collect information regarding quality of colostrum offered, and this may have influenced ADG (Faber et al. Reference Faber, Faber, McCauley and Ax2005), although farm management mandated offering frozen colostrum if dam colostrum was of insufficient quality. Dam parity did not significantly affect pre-weaning ADG (P > 0·05), with 536 vs 570 g/d for progenies of primiparous vs multiparous cows, respectively. As a result, weaning BW also followed a similar trend and multiparous cows had heavier calves at weaning (P < 0·01). Yaylak et al. (Reference Yaylak, Orhan and Daşkaya2015) reported that a one kg increase in birth BW caused an increase of 890 g in weaning weight and a decrease of 1·26 g in daily live weight gain. Kertz & Loften (Reference Kertz and Loften2013) suggested that at increase of 680 g in ADG would double calf birth weight by the end of 2 months of age. Our data suggests that this relationship does not apply across all farms, as the calves in our study were able to more than double body weight at lower ADG. This further suggests that optimal calf growth may depend on initial body weight.
Growth and performance data on heifers’ and cows’ offsprings
Hip height at weaning tended to be lower in calves from primiparous dams compared to calves from multiparous dams (P < 0·06). Overall height of weaned calves (83·7 cm) was nearly 10 cm lower than that reported by Soberon et al. (Reference Soberon, Raffrenato, Everett and Van Amburgh2012), which may be due to different genetics and differences in mature body sizes of cows between our dataset and theirs. Similarly, the cows in our study were older at first calving compared to the data reported by Soberon et al. (Reference Soberon, Raffrenato, Everett and Van Amburgh2012), and may reflect the different management strategies in the two countries.
Although the actual 305-d milk yield tended to be greater in calves from primiparous dams compared to calves from multiparous dams this difference was not significant (P > 0·05; Table 1). There was no difference in milk fat and protein yield between parities. Older data (Lubritz et al. Reference Lubritz, Forrest and Robison1989) using Hereford cattle, found that calves born to young dams produced more milk. The present study found a similar relationship between dam parity and milk production. Recent data (Hinde et al. Reference Hinde, Carpenter, Clay and Bradford2014; Græsbøll et al. Reference Græsbøll, Kirkeby, Nielsen and Christiansen2015) showed that milk production at first and second lactation could be affected by the sex of the calf at first calving, it appears that these kind of data should be interpreted with caution and more studies are needed to clarify the relationship between pre-weaning ADG, age of dam and calf sex on first lactation milk yield.
Milk production and pre-weaning ADG tended to be positively correlated, (P = 0·06; Table 2). This observation is in agreement with Soberon & Van Amburgh (Reference Soberon and Van Amburgh2013) and Soberon et al. (Reference Soberon, Raffrenato, Everett and Van Amburgh2012) who showed, in milk replacer fed calves, the higher pre-weaning ADG the more milk production in first lactation. Soberon et al. (Reference Soberon, Raffrenato, Everett and Van Amburgh2012) suggested that a 400 g increase in pre-weaning ADG would result in 621 kg more milk production in the first lactation and there is no plateau in response to pre-weaning nutrient intake. In contrast with the current study, more recently Kiezebrink et al. (Reference Kiezebrink, Edwards, Wright, Cant and Osborne2015) indicated that higher whole-milk feeding and, in turn, greater ADG was not translated to more milk production in first lactation. However, the calves in their study were kept under a controlled environment which is completely different from what happens in the real conditions inside the farm.
Correlation coefficient and equations developed from linear regression of the following pre-weaning and management parameters with 305 d milk yield
In conclusion the results of this study show that under farm conditions, the effects of pre-weaning ADG (obtained by whole milk feeding) and dam parity on future milk production are relatively small, albeit with a tendency for a positive effect of higher ADG.
Supplementary material
The supplementary material for this article can be found at http://dx.doi.org/10.1017/S0022029916000558
The authors gratefully thank Dr A. Bach for his instructive guidance in statistical analysis. We thankfully acknowledge Dr R. A. Patton and Mr Saman Jamshidi for English improvement of this paper.
