The present study aimed at (1) describing age-related changes in faecal bacterial functional groups involved in carbohydrate degradation and in their activities in foals (n 10) from birth (day (d) 0) to 6 months (d180) and (2) investigating the effect of maternal supplementation (five mares per treatment) from d2 45 to d60 with fermented feed products on response trends over time of the foal bacterial carbohydratedegrading capacity. Maternal supplementation with fermented feed products stimulated foal growth from d0 to d60 and had an impact on the establishment of some digestive bacterial groups and their activities in foals from d0 to d5 but not in the longer term. Irrespective of the maternal treatment, total bacteria, total anaerobic, lactate-utilising and amylolytic bacteria were established immediately after birth (P, 0·05) and were active as shown by the significant increase in total volatile fatty acids. In the foals of supplemented mares, total anaerobes and lactate utilisers were established rapidly between d0 and d2 (P¼ 0·021 and 0·066, respectively) and the increase in the percentage of propionate occurred earlier (P¼0·013). Maternal supplementation had no effect on the establishment of fibrolytic bacteria and their activity. Cellulolytic bacteria and Fibrobacter succinogenes first appeared at d2 and d5, and increased progressively, reaching stable values at d30 and d60, respectively. From the second week of life, the increase in the molar percentage of acetate and the ratio (acetate þ butyrate):propionate (P, 0·05) suggested that fibrolytic activity had begun. From d60, only minor changes in bacterial composition and activities occurred, showing that the bacterial carbohydrate-degrading capacity was established at 2 months of age.

SUMMARYDespite practical information and applied results from numerous experimental studies and/or field observations, there is a persistent gap between scientific recommendations and on-farm reality. There are numerous published reports on the impact of dairy heifer herd management conditions on short-term, medium-term and long-term performances, but few studies on actual dairy heifer herd management practices – particularly in France. In an attempt to address this shortfall, a survey was conducted in 2010 on 449 herds located in the second largest dairy production region, the Pays de la Loire region (Western France). Economic-related aspects of heifer farming were not addressed. The essentially qualitative survey information was collected by 107 independent agricultural technologists. A quantitative analysis based on a small set of the most representative key production criteria was also conducted on a representative sub-sample of 286 herds. Mean herd size, at 46·6 cows per farm, and milk production, at 7953 kg milk/cow/lactation, were close to French national averages (47·3 cows per farm and 8109 kg milk/cow/lactation). The survey covered nine core themes and confirmed an all-round lack of precise monitoring on animal growth, as reported in earlier studies performed outside France. Most of the farmers surveyed considered animal weight a useful indicator for estimating growth performance. However, very few actually weighed their animals, despite the fact that 0·80 of the farmers surveyed aimed to calve their heifers before 30 months of age, with 0·55 of them setting a minimum calving weight target of at least 610 kg. Mean calf age at weaning was 2·9 months, but in practice this was >3·5 months in 0·31 of cases. Although farmers differ on certain practices, common core foci emerged: weight or age targets for pre-determined growth and development stages (at weaning or at service), recycling non-marketable milk for feeding young calves, essentially visual oestrus detection methods, and others. Based on the farmers’ declarations, the estimated time spent rearing a heifer from birth to calving ranges from 12 to 15 h per animal, with most farmers spending an estimated 0–2 h/day rearing their heifers. While almost two-thirds of farmers stated that rearing heifers was a necessity, 0·36 of this survey population claimed they enjoyed the work, whereas 0·02 of the farmers felt the work was purely a chore. Mirroring the conclusions from other countries, dairy heifer herd performances could be improved through better animal monitoring and management.

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