This study sets out to measure CWU (litre/kg ECM, energy-corrected milk) of typical milk production systems in 60 dairy regions from 49 countries representing 85% of the world׳s milk production. The extended version of TIPI-CAL 5.2 including water model was used for data analysis.The results have shown the CWU/kg ECM ranged between 739L on the Danish farm to 5622 l on the Ugandan farm with a global average of 1833L. When looking at averages per region, the CWU was lowest in Europe (913L) and highest in Africa (3384L) with large intra- and inter-regional differences. Compared with grazing and intensive production system, low yielding cows on small-scale farms have the highest CWU/kg ECM. The key driver for variation in CWU/kg ECM is feed, accounting for 94–99% of the total CWU. Increasing milk productivity might be one of the promising ways to reduce CWU/kg ECM. However, this might also lead to the negative impact into water supply systems if this increase is dependent on land irrigation in water scarce areas. The findings of this study showed the need to address the location of the farm, the feed quality, feeding system and milk production intensity simultaneously when aiming at efficient water resource management which would help to contribute food production and livelihood security of dairy farmers worldwide.

Effect of evaporative cooling of pregnant dairy cows under heat load conditions during the dry and close-up period, on mammary gland enzymatic activity and intake of food and water, BCS, and milk performance after calving were measured in two consequent experiments. In experiment 1, 18 dry cows held in tie-stalls in a closed aerated barn under heat load conditions were used to measure the effect of evaporative cooling on the respiratory rate and body temperature, individual intake of food and water, enzymes expression level in mammary gland and adipose tissues, and BCS changes until calving. In experiment 2, two groups of 36 dry cows each, held in a commercial loose housing barn, were used to measure the effects of evaporative cooling under heat load conditions on calves' birth weight, colostrum quality and quantity, BCS changes and milk yield during 90 DIM. The non cooled (NC) cows responded to heat load by increasing their respiratory rate and daily water intake, while elevating their rectal temperature by 0.2-0.3 °C as compared with the cooled (C) cows. The external relief of heat load by the C cows in both experiments was expressed in increasing their voluntary DMI during the dry period as compared with the NC group. In experiment 2 the calves' birth weight of C cows was higher, and their colostrum quality and quantity were improved as compared with the NC group. Cooling also improved significantly BCS gain during the last 21 days until parturition, accompanied with higher cell proliferation process (based on enzymes expression at mRNA level) in the mammary gland of the C cows. Consequently, a significant increase in milk production by 5.3%, protein yield by 5.1%, ECM yield by 4.2% and FCM yield by 4.5%, was demonstrated in the C cows during 90 DIM as compared with the NC group.

L'herbe fraîche est un aliment de bonne valeur alimentaire pour les ruminants mais son ingestion par les vaches laitières reste limitée au regard de sa digestibilité. La forte teneur en eau de l'herbe fraîche pourrait limiter la quantité ingérée de MS d'herbe. L'effet de l'eau externe à la plante sur l'ingestion, le comportement alimentaire et l'encombrement ruminal a été étudié sur des vaches laitières nourries à l'auge avec du ray-grass anglais distribué ad libitum. Trois traitements ont été comparés : herbe verte témoin, fauchée une fois par jour (C)C plus de l'eau ajoutée sur l'herbe (SW) et C plus perfusion d'eau dans le rumen après chaque distribution (PW). La distribution d'herbe a été faite à 14:00 h, 19:00 h et 07:00 h le lendemain matin. L'eau de boisson était en accès libre. Dans le traitement SW, la teneur en MS de l'herbe offerte a été réduite de 161 à 117 g / kg brut ( P 0,02) sans changer la composition chimique de l'herbe. Par rapport à C et PW, la quantité brute ingérée d'herbe et la vitesse d'ingestion en brut ont fortement augmenté (respectivement + 36 et 39 pour cent), mais la quantité de MS d'herbe ingérée (16,4 kg MS/ j), la vitesse d'ingestion de MS (35,3 g MS/min) et les durées journalières d'ingestion (468 min) et de rumination (515 min) n'ont pas été modifiées. Perfuser l'eau dans le rumen n'a affecté ni l'ingestion ni le comportement alimentaire. Le poids total du contenu du rumen (150 kg), la teneur en MS du contenu (115 g/kg ), l'osmolarité du liquide ruminal, la proportion d'eau libre et d'eau liée ainsi que le taux de renouvellement des liquides n'ont pas été modifiés par les traitements. En conclusion, pour des vaches en production nourries à l'herbe, un apport même important d'eau externe ne constitue pas de limite à la prise alimentaire, ni à l'encombrement dans le rumen, et n'affecte pas la quantité de MS d'herbe ingérée