Milk production responses to different strategies for feeding supplements to grazing dairy cows

Abstract

Milk production responses of grazing cows offered supplements in different ways were measured. Holstein-Friesian cows, averaging 45 d in milk, were allocated into 8 groups of 24, with 2 groups randomly assigned to each of 4 feeding strategies. These were control: cows grazed a restricted allowance of perennial ryegrass pasture supplemented with milled wheat grain fed in the milking parlor and alfalfa hay offered in the paddock; FGM: same pasture and allowance as the control supplemented with a formulated grain mix containing wheat grain, corn grain, and canola meal fed in the parlor and alfalfa hay fed in the paddock; PMRL: same pasture and allowance as the control, supplemented with a PMR consisting of the same FGM but mixed with alfalfa hay and presented on a feed pad after each milking; and PMRH: same PMR fed in the same way as PMRL but with a higher pasture allowance. For all strategies, supplements provided the same metabolizable energy and grain:forage ratio [75:25, dry matter (DM) basis]. Each group of 24 cows was further allocated into 4 groups of 6, which were randomly assigned to receive 8, 12, 14, or 16 kg of DM supplement/cow per d. Thus, 2 replicated groups per supplement amount per dietary strategy were used. The experiment had a 14-d adaptation period and a 14-d measurement period. Pasture allowance, measured to ground level, was approximately 14 kg of DM/d for control, FGM, and PMRL cows, and 28 kg of DM/d for the PMRH cows, and was offered in addition to the supplement. Positive linear responses to increasing amounts of supplement were observed for yield of milk, energy-corrected milk, fat, and protein for cows on all 4 supplement feeding strategies. Production of energy-corrected milk was greatest for PMRH cows, intermediate for FGM and PMRL cows, and lowest for control cows. Some of these differences in milk production related to differences in intake of pasture and supplement. Milk fat concentration decreased with increasing amount of supplement for all feeding strategies, but the decline was most marked for the control cows. Milk protein concentration increased for all groups as the amount of supplement increased, but was greater for FGM, PMRL, and PMRH cows than control cows. It is concluded that when supplements are fed to grazing dairy cows, inclusion of corn grain and canola meal can increase milk production even at similar metabolizable energy intakes, and that it does not matter whether these supplements are fed as a PMR or in the parlor and paddock.

Challenges of feeding dairy cows in Australia and New Zealand

“…Relationship between DM intake (% liveweight) and feed conversion efficiency (kg energy-corrected milk/kg DM intake) for cows in early lactation consuming either cereal grain in the dairy at milking time and forage in the paddock (&), or partial mixed ration (PMR), including canola fed twice daily on a feedpad (PMR; ·). Data are from Auldist et al (2014Auldist et al ( , 2016 0.6 to 0.75 to 1.0 m and feeding behaviour improved, with the effects being greatest for subordinate cows (Hetti Arachchige et al 2014).…”

“…Environmental benefits are also possible through the use of supplementary feeding to dilute N intake and increase milk production, which increases the efficiency of N use and potentially reduces N leaching. Beukes et al (2014) suggested that N-use efficiency of standard pasture only was~14% and we calculated that diets based on formulated grain mixes can improve the conversion of dietary crude protein intake to milk protein to 26%, on the basis of data presented in Auldist et al (2016).…”

Incorporating mixed rations and formulated grain mixes into the diet of grazing cows: Effects on milk composition and coagulation properties, and the yield and quality of Cheddar cheese

“…These responses were associated with higher and less variable ruminal pH and increased DMI of both pasture and supplement. Further, a companion paper to the current experiment (Auldist et al, 2016), showed that most of the milk production benefits of PMR feeding strategies could be obtained by feeding the grain components of the PMR (i.e., cereal grain, corn grain, and canola meal) in the parlor using the existing automated feeding infrastructure. Such feeding strategies would be relevant to a larger proportion of producers in the pasture-based dairying regions of Australia, the majority of whom do not own mixer wagons or feed pads.…”

“…These diminishing returns are probably partly due to increases in the variation of ruminal fluid pH and the time per day that the pH is below 4197 6.0 (Wales and Doyle, 2003). This can be associated with impaired rumen fermentation and NDF digestion (Mould et al, 1983;Dixon and Stockdale, 1999;Wales et al, 2000) and reduced DMI and milk production when high amounts of grain are ingested over a short period (Auldist et al, , 2016.…”

Effect of increasing dietary metabolizable protein on nitrogen efficiency in Holstein dairy cows

“…Similarly, a variation in MNE exists due to difference in stage of lactation [6]. In intensive production system, MNE varies from 25% to 35% [7] and from 21% to 27% in pasture based extensive production system [8]. The environmental temperature also affects MNE and it decreases with increasing temperature [9].…”