Context
To be competitive and increase profits, farmers have to reduce their production costs. In suckling cattle systems, management of heifers for early calving can help to reach this target. This practice reduces the unproductive life time of the animal by 6 to 12 months and, theoretically, with a same calving number, leads to decrease the stocking rate at the farm level. Albeit technically feasible, this practice is fairly uncommon and farms practising it tend to be more intensive(more concentrate feed and more fertilizers for forage production). The main factor restricting early calving remains heifers live weight at first insemination. They must reach 65 to 70 % of their adult weight to say 400 to 420 kg at 14-15 month-old. In such context, the average daily gain (ADG) from birth to first insemination must reach, at least, 0.750 kg.
Objectives
The objective of this 3 years study is to show that it is possible to lead heifers for early calving with an optimal utilisation of grass and forages produced on farm. To reach such an objective, 2 trials were defined :
- one to determine the impact of winter diets on heifer performances during he following grazing period.
- one to determine the grazing performances of 6 month-old heifers during their first grazing season.
Results obtained
IMPACT OF WINTER FEEDING ON GRAZING PERFORMANCES
The main results of this 3 years experiment are summarized in table 1. Winter ADG was significantly influenced by the basal diet (forage = FOR or concentrate = CON) and by the level of nitrogen supplementation (115N or 100N) with no interaction between these factors. Concentrate-fed heifers were heavier at spring. Differences in live weight at the end of winter were 20 to 30 kg at the benefit of heifers receiving concentrate-based diets. The same observation can be made for the nitrogen level of the diet : 115N diets lead to the best animal performances. Nevertheless, from an economical point of view, forage-based diets remained the cheapest with an averaged daily cost of 0.91 € per animal per day. CON diets were 0.31 € more expensive with an averaged daily cost of 1.22 € per animal per day. For a 150 days period under cowsheet, this difference is important. But had winter diet an impact on performances during the next grazing season? For the 4 winter diets, ADG decreased at the beginning of grazing season. This decrease was sharper for heifers that previously had the best winter performances. Heifers previously fed with forage diets maintained their level of performances and at the end of the grazing season, there was any weight difference between the both basal diets (FOR or CON). In average, the weight of 420 kg was reached for all 15 to 18 months heifers. [image]
UTILISATION OF GRAZED GRASS BY 6 MONTH-OLD HEIFERS
With a good quality grass (940 VEM, 89 g of digestible protein in the intestine (DVE in Dutch system), 16.5 % of crude protein) supplemented with 0.5 to 1 kg of breeding concentrate, grazing performances reached 0.576 kg/day (averaged value for the 3 years heiferstrials). The between year variability was high. If 2001 and 2003’s ADG were similar with 0.649 and 0.765 g/day, it was lower in 2002 (0.311 kg) with the same grass quality and availability! During the following stalling period, heifers fed with grass silage had higher daily intake. Level of intakes for hay or concentrate diets were smaller and similar. ADG was significantly higher for concentrate diet with 0.885 kg. Performances of forage based diet were lower with 0.746 and 0.630 kg/day respectively for hay and grass silage. From the zootechnical point of view, concentrate and hay diets allowed to reach the best performances but, as in the first experiment, forage diets remained economically interesting. All heifers could be inseminated between 15 and 18 months but concentrate fed heifers weighed 420 kg 1.5 months earlier. To conclude, at the end of those 3 years, it is possible to achieve early calving with feeding schemes including 50 to 70 % of farm forage in the diet. Protein overfeeding doesn’t improve performances and is expensive. Close attention needs to be paid to forage quality if an ADG of 0.750 kg is to be reached. This practice should benefit to suckling cattle breeders both in term of technico-economical and environmental performances.
Contribution
The Farming Systems Section is the project leader. It was occupied of the establishment and the follow-up of the project, as of the analysis of the results.
Partners
DGA : financial participation.
Local breeders : experimental animals loan.
CRAW off coordinator
Ir. Virginie Decruyenaere
CRA-W – Section Systèmes agricoles
Rue de Serpont, 100
B-6800 Libramont-Chevigny
Tel. : +32 (0)61 23 10 10
Fax : +32 (0)61 23 10 28
Email : decruyenaere@cra.wallonie.be
Funding
- CRA-W - Walloon Agricultural Research Centre
- DGARNE
Team
