Concentrate reduction and sequential roughage offer to dairy cows: effects on milk protein yield, protein efficiency and milk quality

Abstract

An experiment was conducted during 6 weeks to evaluate effects of a reduced dietary level of protein-rich concentrates in a moderate dairy production system on cows' performance, protein efficiency and milk quality including fatty acid profiles. Twenty-three lactating cows (Swiss Fleckvieh) were assigned either to a group receiving on average 2.4 kg/d individually fed concentrates (Prot+, n = 12) or to a group receiving no individually fed concentrates (Prot-, n = 11). All cows had ad-libitum access to a total mixed ration (TMR) mainly based on grass and maize silage, hay and little potatoes and soybean cake. In weeks 4-6 of the experiment, part of the hay was excluded from the TMR, and fed separately in the morning. Individual feed intake and milk yield were recorded during weeks 3 and 6 of the experiment; at the same time feed, faeces and milk samples were collected twice per week for analyses. Data were processed in linear mixed models. Omission of individual concentrates in Prot- was fully compensated by higher roughage intake in terms of dry matter. Crude protein (CP) and net energy intake was almost maintained. Despite a lower apparent CP digestibility in Prot-, the ratio of milk protein to ingested CP was the same in both groups, indicating a higher ruminal utilisation of degraded CP in Prot-. This corresponded with lower milk urea concentrations in Prot-. Milk quality was affected in terms of lower concentrations of linoleic and conjugated linoleic acid in milk fat of Prot-. Concentrations of odd- and branched-chain fatty acids in milk were increased in Prot-. Sequential offer of hay and TMR did not lead to considerable effects in intake, efficiency and milk quality. In conclusion, the results indicate that the efficiency of feed protein utilisation for milk protein is not impaired if concentrates are reduced in a moderate- to low-input dairy production system.

Graded supplementation of chestnut tannins to dairy cows fed protein-rich spring pasture: effects on indicators of protein utilization

“…A pre-treatment sampling week (week 0) served to collect baseline data. For the following 21 days (weeks 1-3), 30 lactating Swiss Fleckvieh cows were randomly assigned to three groups of ten animals each and allocated to treatments with pellets containing 0, 50 or 100 g/kg of chestnut tannin extract (TAN0, TAN50 or TAN100); targeted at approximately 0, 5 or 10 g extract/kg of total dietary dry matter (DM) based on supplementation of 2 kg pellets/day and an estimated total daily feed intake of 20 kg DM for all cows (Leiber et al, 2015a). Data and sample collection were carried out in weeks 0, 1 and 3.…”

“…With near infrared reflectance (NIR) spectroscopy (NIRFlex N-500, Büchi, Flawil, Switzerland) the concentrations of dry matter (DM), total ash, crude protein and fibre fractions (i.e., neutral and acid detergent fibre, NDF and ADF) in forage and faeces samples were determined. The NIR device was calibrated with 180 forage (from different grass-herb swards) and 45 faeces samples (from five different farms, including samples from the present study), which had been analyzed for proximate compounds with standard methods (Leiber et al, 2015a). The content of ash-free acid detergent lignin (ADL) in forage samples was determined with sulphuric acid (75%, v/v) (Fibretherm FT 12, C. Gerhardt GmbH & Co. KG, Königswinter, Germany).…”

Apparent recovery of C18 polyunsaturated fatty acids from feed in cow milk: A meta-analysis of the importance of dietary fatty acids and feeding regimens in diets without fat supplementation

“…Apart from fat supplementation, the principal diet type (e.g., forage proportion, grazing vs. conserved forage) considerably influences the levels of C18 PUFA in milk fat. For example, feeding pasture grass leads to higher contents of PUFA (Dewhurst et al, 2006) and dietary concentrates may enhance LLA proportion in milk fat Leiber et al, 2015). The level of intake of the respective FA and, therefore, their content in the diet is an obvious cause being discussed.…”

Graded replacement of maize grain with molassed sugar beet pulp modulated ruminal microbial community and fermentation profile in vitro

“…Grains are rich in starch, and feeding grains in large amounts increases the risk of metabolic disorders such as subacute ruminal acidosis in cows . Besides, the feeding of human edible grains contradicts the ruminants' ability to convert fibrous and human inedible plant material into high‐quality human edible protein sources and increases the food versus feed competition and the pressure on arable production land . Molassed sugar beet pulp (Bp), a by‐product of the sugar industry, has been commonly used in dairy cow nutrition for a long time as an alternative energy source for dairy cattle.…”

“…2 Besides, the feeding of human edible grains contradicts the ruminants' ability to convert fibrous and human inedible plant material into high-quality human edible protein sources and increases the food versus feed competition and the pressure on arable production land. 3,4 Molassed sugar beet pulp (Bp), a by-product of the sugar industry, has been commonly used in dairy cow nutrition for a long time as an alternative energy source for dairy cattle. Since Bp is inedible for humans, feeding of Bp to dairy cows offers an opportunity to convert human inedible plant material into milk and meat.…”