Animal diet quality during the grazing season in two mountain low-input dairy systems
2016
Mesquita, F L de S R | Farruggia, A | Andueza, D | Piccard, F | Le Morvan, A | Quereuil, A | Carvalho, PCF | Fournier, F | Pomiès, D
When animals graze swards at moderate or low stocking rate and hence have feeding choices to make within heterogeneous vegetation, the quality of their diet is difficult to assess. In such grazing conditions, the evaluation of the selected herbage digestibility through the analysis of the content of their faeces is a relevant alternative. The objective of this study was to examine the evolution of grazing animals’ diet quality in two experimental grassland-based dairy systems (called “extensive” and “intensive”), using this indicator. About 800 faeces samples from cows and heifers have been collected by rectal sampling when animals were grazing during three periods (spring, summer, autumn) over 4 years in both systems. Each system was designed with 12 Holstein cows, 12 Montbéliarde and heifers for herd renewal, a short calving season at spring, a low (0.66 LU per ha), or moderate (1.09 LU per ha), stocking rate, no concentrate or a weak amount (4 kg per d during 200 days). A significant decrease in cows’ diet digestibility (-4.9 per cent) was observed in the “extensive” system in summer while a slight, regular but significant decrease was assessed in the “intensive” system (-2.2 per cent). Significant difference of digestibility was found between breeds and between cows and heifers, within sys- tem. No positive relationship between digestibility and milk production was highlighted in the “intensive” system while significant correlations were found in summer and autumn in the “extensive” one, suggesting a limiting energy value of the diet at this period for this system
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