Managing variations in dairy cow nutrient supply under grazing

Abstract

Grazed pasture, which is the cheapest source of nutrients for dairy cows, should form the basis of profitable and low-input animal production systems. Management of high-producing dairy cows at pasture is thus a major challenge in most countries. The objective of the present paper is to review the factors that can affect nutrient supply for grazing dairy cows in order to point out areas with scope for improvement on managing variations in nutrient supply to achieve high animal performance while maintaining efficient pasture utilisation per hectare (ha). Reviewing the range in animal requirements, intake capacity and pasture nutritive values shows that high-producing cows cannot satisfy their energy requirements from grazing alone and favourable to unfavourable situations for grazing dairy cows may be classified according to pasture quality and availability. Predictive models also enable calculation of supplementation levels required to meet energy requirements in all situations. Solutions to maintain acceptable level of production per cow and high output per ha are discussed. Strategies of concentrate supplementation and increasing use of legumes in mixed swards are the most promising. It is concluded that although high-producing cow cannot express their potential milk production at grazing, there is scope to improve animal performance at grazing given recent developments in our understanding of factors influencing forage intake and digestion of grazed forages.

The effect of concentrate allocation on traffic and milk production of pasture-based cows milked by an automatic milking system

“…In our study, higher pasture nutritional values were observed compared with those reported by McEvoy et al (2008), Bargo et al (2002) and Pérez-Prieto et al (2011), promoting higher pasture intake and lower grass to concentrate substitution rate. The negative MR observed in May presumed a low substitution rate and could be explained by the high WSC content of spring pasture promoting increase in pasture intake and in MY, which is in accordance with other authors (Peyraud and Delagarde, 2013;John et al, 2016).…”

“…Following the literature (Dufrasne et al, 1996;Reis and Combs, 2000;Bargo et al, 2002;Kennedy et al, 2003;McEvoy et al, 2008;Auldist et al, 2013), several factors influence the effect of concentrates supplementation on average milk yield and composition -for example, pasture availability and quality, stage of lactation and genetic merit. At high pasture allowance, pasture quality influences pasture intake: Peyraud and Delagarde (2013) reported that pasture intake could vary from 18.9 kg DM/cow per day for excellent pasture quality to 15.5 kg DM/cow per day in very poor pasture quality. In our study, higher pasture nutritional values were observed compared with those reported by McEvoy et al (2008), Bargo et al (2002) and Pérez-Prieto et al (2011), promoting higher pasture intake and lower grass to concentrate substitution rate.…”

“…in May), closer figures to those reported in other studies would be obtained confirming that the effect of concentrates on MY was influenced by pasture availability and quality. Grazing management (strip-grazing modulating pasture allowance) could also be invoked to explain lower MR (Peyraud and Delagarde, 2013).…”

“…In parallel, the interest for combining robotic milking with grazing has increased (Lyons et al, 2013a;John et al, 2016). Grazing has several advantages with the most frequently cited ones including benefits for animal health (Burow et al, 2011) and for the environment (Peyraud and Delagarde, 2013) which are positively perceived by the consumers (De Olde et al, 2016). Including grazed pasture in cows' diet lowers milk production costs (Hongerholt et al, 1997;Dillon et al, 2005) in comparison with barn feeding, and increases the ratio of polyunsaturated fatty acids in cows' milk (Stockdale et al, 2003;Wales et al, 2009).…”

“…They concluded that concentrate supplementation was not effective at attracting the cows to the robot. Studies conducted on grazing cows demonstrated that concentrate supplementation induces a substitution rate effect decreasing cow pasture intake and impacting efficient utilisation of grazed pasture Peyraud and Delagarde, 2013). For grazing dairy cows milked by an AMS, the dilemma between efficient utilisation of pasture and cow traffic to the robot, encouraged by concentrate supplementation, has to be considered.…”