Effects of different strategies for feeding supplements on milk production responses in cows grazing a restricted pasture allowance
- 1 February 2013
- journal article
- research article
- Published by American Dairy Science Association in Journal of Dairy Science
- Vol. 96 (2), 1218-1231
- https://doi.org/10.3168/jds.2012-6079
Abstract
Milk production responses of grazing cows offered supplements in different ways were measured. Holstein-Friesian cows, averaging 227 d in milk, were allocated into 6 groups of 36, with 2 groups randomly assigned to each of 3 feeding strategies: (1) cows grazed perennial ryegrass pasture supplemented with milled barley grain fed in the milking parlor and pasture silage offered in the paddock (control); (2) same pasture and allotment supplemented with the same amounts of milled barley grain and pasture silage, but presented as a mixed ration after each milking (PMR 1); and (3) same pasture and allotment, supplemented with a mixed ration of milled barley grain, alfalfa hay, corn silage, and crushed corn grain (PMR 2). For all strategies, supplements provided the same metabolizable energy and grain: forage ratio. [75:25, dry matter (DM) basis]. Each group of 36 cows was further allocated into 4 groups of 9, which were assigned to receive 6, 8, 10, or 12 kg of supplement DM/cow per day. Thus, there were 2 replicated groups per supplement amount per dietary strategy. The experiment had a 14-d adaptation period and an 11-d measurement period. Pasture allotment was approximately 14 kg of DM/d for all cows and was offered in addition to the supplement. Positive quadratic responses to increasing amounts of supplement were observed for yield of milk, energy-corrected milk (ECM), and fat and protein, and positive linear responses for concentrations of fat and protein for cows on all 3 supplement feeding strategies. No difference existed between feeding strategy groups in yield of milk, ECM, or protein at any amount of supplement offered, but yield and concentration of fat was higher in PMR 2 cows compared with control and PMR 1 cows at the highest amounts of supplementation. Responses in marginal ECM production per additional kilogram of supplement were also greater for PMR 2 than control and PMR 1 cows when large amounts of supplement were consumed. For all diets, marked daily variation occurred in ruminal fluid volatile fatty acids and pH, especially in cows fed the largest amounts of supplement. It was concluded that when supplements are fed to grazing dairy cows, a simple mix of grain and pasture silage has no benefit over traditional strategies of feeding grain in the parlor and forage in the paddock. However, yield of milk fat and marginal milk production responses can be greater if the strategy uses an isoenergetic ration that also contains alfalfa hay, corn silage, and corn grain.Keywords
Funding Information
- DPI and Dairy Australia
This publication has 29 references indexed in Scilit:
- Evaluating development options for a rain-fed dairy farm in GippslandAnimal Production Science, 2010
- The Definition of Acidosis in Dairy Herds Predominantly Fed on Pasture and ConcentratesJournal of Dairy Science, 2008
- Feed conversion efficiency as a key determinant of dairy herd performance: a reviewAustralian Journal of Experimental Agriculture, 2007
- Effect of grain processing degree on intake, digestion, ruminal fermentation, and performance characteristics of steers fed medium-concentrate growing diets1Journal of Animal Science, 2005
- NUTRITIONAL REGULATION OF MILK FAT SYNTHESISAnnual Review of Nutrition, 2003
- Invited Review: Production and Digestion of Supplemented Dairy Cows on PastureJournal of Dairy Science, 2003
- Ruminal Digestion and Fermentation of High-Producing Dairy Cows with Three Different Feeding Systems Combining Pasture and Total Mixed RationsJournal of Dairy Science, 2002
- Synchronization of Carbohydrate and Protein Sources on Fermentation and Passage Rates in Dairy Cows,,Journal of Dairy Science, 1999
- Associative effects between forages and grains: consequences for feed utilisationAustralian Journal of Agricultural Research, 1999
- Lactational Response of Dairy Cows to Diets Varying in Ruminal Solubilities of Carbohydrate and Crude ProteinJournal of Dairy Science, 1989