Farm Ireland

Sunday 25 February 2018

Get the best growth rates from your herd

Denis Minogue

The Derrypatrick Herd is a grass-based, spring- calving, suckler calf-to-beef system in which, bull and heifer progeny are slaughtered at 18 and 20 months of age, respectively. It comprises of four breed types; Limousin-cross Holstein-Friesian, Limousin-cross Simmental, Charolais-cross Limousin and Charolais-cross Simmental.

Calves are weaned in late October (7-8 months of age) and housed indoors. They are offered high quality grass silage and additionally, bulls are offered 2kg and heifers 1kg of concentrate per head daily. During the indoor winter period liveweight gain is 0.5kg/day for the heifers and 0.7kg/day for the bulls.

The objective of this modest growth rate is to take advantage of compensatory growth during the following grazing season. The yearling bulls spend around 100 days and the heifers 200 days at grass.

Bulls are offered concentrates ad-lib (following gradual adaptation) with 5kg of fresh silage/hd/day over 90 days, and heifers are offered grass silage ad-lib and 5kg of concentrate/hd daily over 60 days.

The calving season started on January 30, and 97pc of the herd have calved within 11.5 weeks. In seasonal grass-based systems, compact calving is a critical factor driving output. Calf mortality was high with seven dead calves. Post-mortem examinations did not reveal why they occurred.

One clear message being developed from this research herd is the importance of milk in the cow. Results from the cow breed evaluation have shown that the progeny (males and females) from Limousin-cross Holstein-Friesian were approximately 50kg heavier at weaning in each of the last two years than the progeny of the Charolais-cross Limousin cows (see the table, above).

This difference in liveweight at weaning was largely maintained right through until slaughter, resulting in a difference of 17kg in carcass weight (males and females). In order to incorporate more milk, and better fertility into our cows, long-term breeding strategies will have to be implemented.

Following turnout to pasture of all stock, the herd demand per hectare rises significantly. Currently, herd demand is about 67kg DM/ha/day, and as the animals grow this feed requirement will gradually increase to 80kg DM/ha/day by the middle of June. Therefore we are relying heavily on appropriate grazing guidelines during this period to prevent feed budget problems. In a typical year, grass growth peaks in late May-June.

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There are several events that relieve grazing pressure in the Derrypatrick system:

• From mid to late June, the yearling bulls are housed for finishing;

• In early August, following second cut silage, more paddocks are available for grazing;

• In mid-September, yearling heifers are housed for finishing;

• The weaning and housing of cows and new progeny.

With temperatures dropping and rainfall increasing, this combination of environmental effects can place highly stocked herds, such as Derrypatrick, under pressure. Thankfully, pasture covers accumulated during the early spring period were available. Heavy pasture covers are delaying the rotation enough to allow regrowth on grazed paddocks. The increased rainfall has meant we are not grazing as tight to minimise damage to the sward; as the farm comprises a proportion of a heavy clay soil.

Management details:

• At present, the herd is at a stocking rate of 5.56LU/ha (around 3,200kg liveweight/ha). Average farm cover is around 1,100kg DM/ha. Herd demand is around 67kg DM/ha, giving 16 days grazing. 90 cows and calves are at grass plus the yearling bulls and heifers. Pasture covers of approximately 2,500kg DM/ha are being grazed by the cows and calves to slow down rotation.

• The breeding season started on April 19. A Blonde D'Aquitane bull is running with 24 replacement heifers, and Charolais bulls are running with mature cows. Cows and heifers were vaccinated against BVD and Leptospirosis before breeding.

• Around 30ha was closed up for first cut silage on April 10. It received nitrogen (urea), nitrogen fertiliser and slurry. Expected harvest date is June 1.

Denis Minogue manages the Derrypatrick Research Herd at Teagasc Grange, Dunsany, Co Meath

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