Sustainable milk production systems in humid areas using farm resources

Abstract

The study in this Thesis of "Sustainable Milk Production Systems In Humid Areas Using Farm Resources" contributes to the knowledge of the main factors to control for reducing feeding costs of milk production in humid areas of the European Arc Atlantic as Galicia (NW Spain). The base of this research is in the use of available farm resources and the management of the grazing system with emphasis on some of the factors derived from pasture (stocking rate, pre-grazing herbage mass, daily herbage allowance, residence time at pasture, source of forage/concentrate in the ration and levels of supplementation at pasture) and animal (state and number of lactation, cow genotype and animal behaviour at grazing/in confinement) that influence on the complex interaction between both. It seeks, thereby, to achieve an efficient conversion from grass into milk, in a competitive and profitable way taking into consideration the current context of the region in which the quality and fatty acid profile of the final product has become particularly relevant in recent years. The work carried out during the current Thesis was divided into three major sections associated to six experimental trials conducted at different European Research Institutes. It was examined some of the most important factors that influence on the interaction between pasture and animal, with the aim of obtaining a multidisciplinary approximation to sustainable pasture-based milk production systems using fresh grass as a main ingredient of the diet in dairy cows. From the trials undertook, it was highlighted the importance of applying appropriate grassland management practices at farm level, whether increasing the stocking rate (Trial 1.1.- CIAM) or changing the sward structural characteristics, combining pre-grazing herbage mass and daily herbage allowance per animal (Trial 1.2.- Moorepark), in order to achieve greater herbage utilization, with lower post-grazing residues and maintain higher sward quality on subsequent grazing rotations. The quality of pastures in these conditions, with lower dry matter and fiber content (acid and neutral detergent) and higher levels of crude protein, water soluble carbohydrates and digestibility provided higher milk quality (with higher content of protein and fat). Choose the type of cow more adapted to the milk production system selected improved its efficiency and in this thesis two milk production systems were evaluated using two cow genotypes (Holstein-Friesian vs. Normande), fed with and without concentrate at pasture (Trial 2.1.- Pin au Haras). The behavioral activities of two cow genotypes (Holstein-Friesian vs. Jersey crossbreed), during daily time budget, were determined in animals managed in a low inputs grazing system vs. a high inputs confinement system (Trial 2.2.- Hillsborough) related to food demands and needs of lying and rumination in both herds. Due to in pasture-based milk production systems, there is a high dependence on fresh grass in the diet of dairy cows it was possible to increase the added value of the final product (milk) with higher content of conjugated linoleic acid. This fatty acid is considered beneficial for human health and its intake was increased using a grazing diet in those Galician farms that relied on pastures for feeding their cows (Trial 3.1.- CIAM). The use of concentrate containing oilseeds in the diet of dairy cows was considered also as a way to improve the fatty acid profile of milk, both at grazing and in stable (Trials 3.1.- and 3.2.- CIAM). In the future, using proper grassland management strategies will be crucial in humid areas in order to optimize sward quality and daily pasture dry matter intake, maximizing milk production per cow and per hectare, with an increase also in milk quality due to better fatty acids profile, and making Galician dairy farms more sustainable and competitive.