Comparing Holstein-Friesian cows with Jersey X Holstein-Friesians milkers on three different levels of concentrate input confirmed that crossbred cattle are more fertile, but found that extra meal fed had no impact on fertility!
Key, practical conclusions from applied research projects completed at the request of milk producers, who provided financial support through AgriSearch, the Northern Ireland Agricultural Research and Development Council.
Dr Elaine Vance, who worked on this AgriSearch supported research as a PhD student, has now presented the final outcomes of the breed comparison component of this study
The ‘Comparison of three contrasting systems of milk production for spring calving dairy cows’ trial comprised two separate components:
1) a comparison of cow performance associated with three contrasting milk production systems
2) an evaluation of the performance of Holstein-Friesian and Jersey x Holstein-Friesian cows when managed on these three milk production systems.
The three grassland-based systems were defined as low concentrate (LC), medium concentrate (MC) or high concentrate (HC). Total concentrate intakes with LC, MC and HC were 530, 1092 and 1667 kg/cow/lactation, respectively.
Dry matter intakes during the early lactation (pre-turnout) period were unaffected by genotype and similarly, during the grazing periods there was no evidence of a difference in herbage intake between genotypes as the smaller J x HF cows modified their grazing behaviour to allow them to achieve intakes similar to the larger Holstein-Friesian cows.
On average, HF cows produced 625 kg more milk than J x HF cows, while milk fat and protein concentrations were 5.8 and 2.9 g/kg higher with the J x HF cows. Fat plus protein yield (milk solids) was unaffected by genotype. Milk yield and fat plus protein yield were higher with MC and HC systems, than with LC.
Table 1 Effect of dairy cow genotype and management system on ‘days in milk’, total lactation concentrate intake and total lactation milk production (mean of Years 1, 2 and 3)
|
|
Genotype (G) |
|
System (S) |
|
|
|
|
|
HF |
J x HF |
|
Low Conc. |
Medium Conc. |
High Conc. |
|
Days in milk |
305 |
302 |
|
299 |
304 |
307 |
|
Concentrate intake (kg DM) |
947 |
963 |
|
466 |
961 |
1467 |
|
Milk yield (kg) |
6252 |
5627 |
|
5399 |
6084 |
6336 |
|
Milk composition (g/kg) |
|
|
|
|
|
|
|
Fat |
42.0 |
47.8 |
|
44.3 |
45.9 |
44.5 |
|
Protein |
33.0 |
35.9 |
|
34.1 |
34.6 |
34.6 |
|
Milk solids yield (kg) |
|
|
|
|
|
|
|
Fat + protein |
467 |
471 |
|
421 |
488 |
498 |
Thus the current study demonstrate that crossbreeding Holstein-Friesian dairy cows with Jersey sires will normally result in a loss in milk yield, but in most cases, no loss in the yield of milk constituents.
Within the range of concentrate levels examined, J x HF cows had the genetic potential to exhibit similar milk yield and milk constituent yield responses as pure bred HF cows. The implication of this is that crossbreeding may have a role within higher concentrate input systems of milk production, rather than being restricted to lower concentrate input systems.
Table 2 Effect of dairy cow genotype and management system on cyclicity, reproductive performance and health parameters (mean of Years 1, 2 and 3)
|
|
Genotype |
|
System (S) |
|
|||
|
|
HF |
J x HF |
|
|
Low Conc. |
Medium Conc. |
High Conc. |
|
Fertility performance (proportional basis unless stated otherwise) |
|
|
|
|
|||
|
Days to first observed heat |
50.5 |
41.7 |
|
|
41.1 |
47.7 |
49.6 |
|
Conception to first service (proportion) |
0.35 |
0.58 |
|
|
0.50 |
0.47 |
0.37 |
|
Conception to first and second service (proportion) |
0.52 |
0.81 |
|
|
0.71 |
0.62 |
0.62 |
|
Pregnancy rate at end of breeding season (proportion) |
0.73 |
0.89 |
|
|
0.80 |
0.79 |
0.82 |
|
Interval from calving to conception (days)2 |
97.5 |
90.1 |
|
|
96.0 |
87.7 |
97.6 |
|
Health parameters |
|
|
|
|
|
|
|
|
Proportion of cows with at least one case of mastitis |
0.29 |
0.16 |
|
|
0.25 |
0.20 |
0.28 |
|
Proportion of cows with at least one case of lameness |
0.19 |
0.11 |
|
|
0.04 |
0.16 |
0.25 |
|
Mean locomotion score |
2.6 |
2.6 |
|
|
2.6 |
2.6 |
2.6 |
HF, Holstein-Friesian; J x HF, Jersey x Holstein-Friesian; LC, Low Concentrate; MC, Medium Concentrate; HC, High Concentrate
2, for cows that became pregnant
In addition, conception rate to first service, conception rate to first and second service and pregnancy rate at the end of the breeding season were 23, 29 and 16 percentage points higher with the J x HF cows, compared to the HF cows.
Previous studies have highlighted the association between negative energy balance, excessive tissue mobilisation during early lactation and reduced fertility performance. However the improved fertility performance with the J x HF cows within the current study occurred despite similar levels of condition score loss with the two genotypes. Hybrid vigour is likely to have been a significant contributor to the improved fertility performance observed with the crossbred cows.
Thus, the findings of this experiment suggest that crossbreeding Holstein dairy cows with Jersey sires is a means to overcome some of the fertility problems widely reported with the Holstein breed. But crossbreeding should not be seen as the way to avoid fertility problems that are due to poor management of the herd.
Although concentrate inputs increased from 530 kg/cow with LC to 1667 kg/cow with HC, there was no evidence that fertility performance increased with increasing concentrate levels.
Somatic cell count was unaffected by genotype in the current study, with previous research suggesting that the effect of hybrid vigour on SCC is low. However, the proportion of cows with one or more cases of mastitis was approximately 45% higher with the HF cows.
There is a perception that Jersey crossbred dairy cows have improved hoof health compared to Holstein cows. Although not significant within the current study, there was a tendency for HF cows to have more cases of lameness perhaps due to Jersey and Jersey crossbred cows having harder hooves.