On the trail of the perfect suckler cow
A good suckler cow is hardy and milky.
Robert Davies reports on a trial which produces some surprising results and hints for the suckler producer looking for replacements
MORE research is needed to develop the ideal suckler cow which produces quality beef off grass.
This is the view of Arthur Davies, the officer in charge of the Institute of Grass and Environ-mental Research Institutes Bronydd Mawr facility, at Trecastle, in Powys.
He believes the need to finish cattle at a younger age will encourage the use of smaller, lower maintenance cows alongside big terminal sires with high growth potential.
With the emphasis certain to be on "natural" production methods, ability to use forage efficiently will become even more important. And some dairy breed genes are likely to be needed to get optimum milk production for calves, says Mr Davies.
Commercial production will be based on cow type, rather than a particular breed or cross. She will need to be able to make the most of particular farm conditions, as well as the management system implemented.
"Work done here shows a big variation between the responses of different types of suckler cows when contrasting levels of nutrition were supplied from grazed pasture," claims Mr Davies.
One of the biggest trials, run in association with the Macaulay Land Use Research Institute, compared Hereford x Friesian (HF), Angus x Friesian (AF) and Welsh Black (WB) suckler cows. All were spring calving and produced Charolais cross calves.
During the summer they grazed permanent pasture maintained at either 4-5cm (short), or 7-8cm (tall) sward heights. Many measurements, shown in the table, were analysed.
Body chemical composition changes of cows were predicted from liveweight and body condition score, using equations derived from information collected when sample cows were slaughtered at a range of body conditions.
Energy balances were calculated. Milk yields and compositional quality were measured by milking cows three times a year for four seasons. A milking bail was used and oxytocin injected to achieve milk let-down. Keeping units on cows that had never been milked before proved to be an interesting way of spending time, remembers Mr Davies.
The effect of sward height on animal performance was significant. Continually grazing at a height of 4-5cm resulted in lower cow herbage intake, liveweight gain, milk yield and calf liveweight gain, than grazing at 7cm to 8cm. At turnout WB cows were 25kg heavier on average than the HF and AF cows. Cows that were fatter at turnout had lower herbage intakes, liveweight gains and milk yields. Differences in yield between the HF and AF cows were small. The WB cows had significantly lower yields.
The WB and HF cows had similar liveweight gains, which were higher than the AF group. Researchers concluded that high milk yields are not necessarily associated with low potential to gain weight during lactation.
Factors other than partition of nutrients between milk and body reserves are important. One of these is herbage intake. Though Welsh Black cows had the highest absolute intake, they achieved similar liveweight gains to the HF cows, and produced less milk.
"This suggests extra intake is required to maintain the larger body mass, which is why I feel smaller cows will be used in future," Mr Davies says.
Calf liveweight gain was closely related to milk yield. The effect of sward height was greatest in calves suckling lower yielding WB cows on low height swards.
This could be explained by the fact that calves can only compensate for a lower milk supply by taking more herbage when grazing conditions allow. The HF and AF cows showed higher land use efficiency on short swards than WBs.
The conclusion drawn from the four-year trial was that dam attributes, such as body size, nutrient partitioning system, and milk yield potential all influence the efficiency of different cows in terms of energy and land use efficiency.
Mr Davies thinks assessment of the performance potential of other breeds under different grazing conditions would be a valuable guide for commercial suckler herd operators. *
• Variation in ability of different types of suckler cows to utilise herbage.
• Variation in partition of available nutrients – ie bodyweight and milk production.
• Calves have the ability to compensate for low milk supply if there is enough good quality grass.
• Milk yield advantage when dairy genetics included in suckler cow type.
• Bigger cows require more maintenance.
Cow and calf performance
Keeping units on suckler cows that have never been milked before proved to be an interesting way of spending time at IGERs Bronydd Mawr facility, Trescatle. But patience won at the end of the day.