Are by-product feed systems appropriate for high producing dairy cows?
Feeding non human edible by-products to dairy cows to produce palatable protein could be construed as a sustainable feeding strategy as farmers can utilise surplus foodstuffs, however the appropriateness of this feeding system for high yielding cows hasn’t been quantified. Suitability was examined by evaluating cow health and fertility traits, and milk quality characteristics, of two genetic lines of Holstein Friesian cows fed a diet consisting solely of by-product (BP) feeds. Data were obtained from the SRUC systems study. Genetic lines are selected for milk fat and protein, either the top 1% of UK genetics (S) or chosen to remain close to average genetics (C). Feeds consisted of straw, sugar beet pulp, breakfast cereal, biscuit meal, distillers’ grains, molasses and soya bean meal. Approx. 50 cows in the two genetic groups were continuously housed and managed to calve all year round. The regime was developed to meet the criteria of a complete by-product diet and could be considered as an extreme because farmers traditionally use these feedstuffs, to complement forages or other imported feeds. Results show that S cows achieved a 26% higher avg. yield than C cows, 10,602 litres for S vs 8,447 for C. Daily yields differed significantly between groups (p<0.001). Select cows consumed more food at 327 tons/year than the C group which averaged 296 tons. Daily DM intakes were significantly different (p<0.001) with means of 20.3 and 22.69 for C and S groups. Milk fat and protein levels were significantly different between groups (p<0.001), with S group means of 3.67 for fat, and 3.17 for protein, whereas the C group generated means of 3.34 for fat and 3.02 for protein. Milk from C cows was of poor quality, as penalties apply at levels of fat below 3.5%, and protein below 3%. Body condition scores and locomotion scores differed significantly between groups (p<0.001). Results show that dairy cows of diverse genetic merits have the ability to produce higher than average yields solely from BP however milk quality was compromised for animals of average merit.
Other Titles/Title of Conference
66th European Federation of Animal Science Annual Meeting, Warsaw, Poland
Wageningen Academic Publishers