Does the amount of pellet, and rate of increase affect performance of fresh cows milked with an automatic milking system?

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Source: SaskMilk, Jennifer Haisan, Masahito Oba and Greg Penner

About the author:

Jennifer is a student at the University of Alberta and conducted this study as a part of her PhD. Jennifer came to the Rayner Dairy Facility to conduct the study as the facility can measure intake of cows housed on an automated milking system (AMS). This data will be presented at the Western Canadian Dairy Seminar during the Student Research Competition on March 12, 2020

Background:

Previous research conducted at the Rayner Dairy Facility by Dr. Greg Penner and his lab using the AMS, with guided cow traffic, has found that there may be no benefit to feeding increased amounts of concentrate through the AMS. These studies, conducted with mid to late lactation cows found that feeding low amounts of concentrate through the AMS (<4 kg/d) did not compromise milk production, milkings per day or dry matter intake (DMI). However, researchers at the University of Guelph compiled data from 9 AMS herds and found that there may be benefits to offering increased amounts of concentrate to early lactation cows to improve energy balance.

Therefore, the objective of this study was to determine if the amount of pellet offered through an AMS, and the rate of increase for the pellet allocation affects DMI, milking frequency, and milk and milk component yield of fresh cows.

What we did:

Fifty-nine cows were fed the same partial mixed ration (PMR; 19.3% starch, DM basis) and assigned to one of three pellet (39.6% starch, DM basis) allowances. Cows received (DM basis) either a Low (3 kg/d), or 1 of 2 High allocations (8 kg/d). Pellet allocations for High treatments increased at a moderate (Mod; increased from 3 to 8 kg over 15 days) or rapid (Rap; increased from 3 to 8 kg over 5 days) rate. All cows stayed in a maternity pen for the first day following calving and were then moved to a free-stall group and milked on the AMS with feed-first guided cow traffic. Amount of AMS pellet offered, PMR intake, milk yield and milking frequency were recorded daily. Milk samples were analyzed weekly for components.

What we found:

The study was conducted for the first 56 days in milk (DIM), however, only data from the first 28 DIM is available at this time.

The average amount of pellet offered to cows during the first 28 DIM were 2.84, 4.15 and 3.96 kg/d for Low, Mod and Rap. PMR intake did not differ between Low and High (15.3 kg/d), however, PMR intake tended to be greater for Mod than Rap (15.4 vs. 14.3 kg/d). Total DMI did not differ between treatments. There were no differences in milking frequency (3.1 milkings/d) or milk yield (40.7 kg/d); however, milk fat concentrations tended to be reduced when High was fed as compared to Low (3.41 vs. 4.09%), resulting in reduced fat yield when High was fed (1.45 vs. 1.66 kg/d).

Take home message:

Offering a High amount of pellet through the AMS did not affect DMI, milk yield or milking frequency; however, there may be negative impacts on milk fat concentrations and yield. Overall, this data suggests there is no benefit to offering increasing amounts of pellet to fresh cows.

Data for the entire 56 day period will be summarized in the coming months and presented in future SaskMilk publications.