Substitution of roughage by concentrates for dairy cows

In recent years, it has become increasingly clear that understanding nutrient partitioning is central to a much broader range of issues than just being able to predict productive outputs. The extent to which nutrients are partitioned to other functions such as health and reproduction is clearly important, as are the efficiency consequences of nutrient partitioning. Further, with increasing environmental variability, there is a greater need to be able to predict the ability of an animal to respond to the nutritional limitations that arise from the environment in which it is placed. How the animal partitions its nutrients when resources are limited, or imbalanced, is a major component of its ability to cope, that is, its robustness. There is mounting evidence that reliance on body reserves is increased and that robustness of dairy cows is reduced by selection for increased milk production. A key element for predicting the partition of nutrients in this wider context is to incorporate the priorities of the animal, that is, an explicit recognition of the role of both the cow's genotype (genetic make-up), and the expression of this genotype through time on nutrient partitioning. Accordingly, there has been a growing recognition of the need to incorporate in nutritional models these innate driving forces that alter nutrient partitioning according to physiological state, the genetically driven trajectories. This paper summarizes some of the work carried out to extend nutritional models to incorporate these trajectories, the genetic effects on them, as well as how these factors affect the homeostatic capacity of the animal. At present, there are models capable of predicting the partition of nutrients throughout lactation for cows of differing milk production potentials. Information concerning genotype and stage of lactation effects on homeostatic capacity has not yet been explicitly included in metabolic models that predict nutrient partition, although recent results suggest that this is achievable. These developments have greatly extended the generality of nutrient partitioning models with respect to the type of animal and its physiological state. However, these models remain very largely focussed on predicting partition between productive outputs and body reserves and, for the most part, remain research models, although substantial progress has been made towards developing models that can be applied in the field. The challenge of linking prediction of nutrient partitioning to its consequences on health, reproduction and longevity, although widely recognized, is only now beginning to be addressed. This is an important perspective for future work on nutrient partitioning.

Section: Introductionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Advances in predicting nutrient partitioning in the dairy cow: recognizing the central role of genotype and its expression through time

Friggens

Brun-Lafleur

Faverdin

et al. 2013

“…Milk response to concentrate however largely depends on the type of cow and genetic merit that determines partition of energy between milk and body reserves. The efficiency of concentrate supplementation at grazing is closely related to energy balance of the cows and substitution rate, thus increasing in high-producing cows, low-quality pasture and low PA (Faverdin et al, 1991;Stockdale, 2000). Concentrate supplementation also increases milk protein content and decreases milk fat content (10.2 g/kg and 0.6 g/kg per kg DM of concentrate, respectively).…”

Section: Variation Of Nutrient Supply At Grazing Relative To Animal Rmentioning

confidence: 99%

Managing variations in dairy cow nutrient supply under grazing

Peyraud

Delagarde

2013

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.

“…An increased intake of concentrate with a rapid rate of increase has shown to decrease the silage intake (Faverdin et al, 1991). The substitution rate (decrease in silage DM intake (DMI) per increase in concentrate DMI) between roughages and concentrates is affected by the state of lactation as well as the concentrate composition (Faverdin et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Effect of the rate of increase in concentrate allowance with concentrates high or low in starch on the performance of dairy cows in early lactation

Mäntysaari

Khalili

2008

The effect of the rate of increase in concentrate allowance after calving with two concentrate mixes (A and B) differing in composition was evaluated using 64 Finnish Ayrshire cows during the first 100 days of lactation. After calving, the concentrate allowance of multiparous cows was increased stepwise from 4 to 17 kg/day, and of primiparous cows from 3 to 13.5 kg/day over 12 days (F rate of increase; multiparous 1.08 kg/day, primiparous 0.88 kg/day) or 24 days (S rate of increase; mutiparous 0.54 kg/day, primiparous 0.44 kg/day). The concentrates were formulated to have similar crude protein and metabolizable energy concentrations but differing starch and NDF concentrations. For concentrate A the starch and NDF concentrations were 421 and 167 g/kg dry matter (DM) and for concentrate B 258 and 251 g/kg DM. All cows received grass silage ad libitum. The higher concentrate intake during weeks 1 to 4 of lactation with F compared with the S rate of increase caused higher DM, energy and protein intake. The higher concentrate intake for F than for S treatment in early lactation did not cause a large decrease in silage intake (8.8 v. 8.3 kg DM/day). The intake of concentrate A and B after calving did not differ for S treatment. However, for F treatment the intake of fibrous concentrate B increased faster than starch-rich concentrate A during weeks 1 to 4 of lactation. The concentrate composition had no effect on energy-corrected milk (ECM) yield during weeks 1 to 4 of lactation for S treatments, but with F treatments the cows fed B concentrate produced more milk. The F rate of increase in concentrate allowance compared with the S rate increased the calculated energy balance after calving. The rate of increase in concentrate feeding post partum or concentrate composition had no effect on DM, energy or protein intake during the whole 100-day experiment. The average ECM yield over days 1 to 100 of lactation was higher for S than for F treatments and tended to be higher with concentrate B than A. Results of this study showed that by the fast rate of increase in concentrate allowance after calving on a grass silage diet, it was possible to improve the energy status of the cows in early lactation. This had, however, no effect on production later in lactation.