Dairy Farmers of Manitoba
Prepared by: Dr. Greg Penner
1. Activities during the reporting period
The project is progressing, generally, as planned. Firstly, 2 M.Sc. students have been recruited as a suitable PhD candidate was not identified.
Activities during the reporting period include:
Two M.Sc. students have been recruited for this project (Silvia Menajovksy and Keshia Paddick)
A total of 16 dairy cattle have been fit with ruminal cannula
Data and sample collection have been completed on the first 2 studies proposed
The first manuscript is currently under co-author review
This study was conducted to evaluate the effects of the forage-to-concentrate ratio of the partial (PMR) and the quantity of concentrate offered in the automated milking system (AMS) on the behavior and performance of dairy cows. Eight ruminally-cannulated multiparous Holstein cows were used in a replicated 4×4 Latin square balanced for carry-over effects. Diets were arranged in a 2×2 factorial consisting of a PMR that contained (DM basis) either a low (54:46; L-FOR) or a high (64:36; H-FOR) forage-to-concentrate ratio and AMS concentrate provided to achieve a low (2 kg/d; L-AMS) or a high (6 kg/d; H-AMS) intake. Each period consisted of 28 d with 6 d for dietary transition, 13 d of adaptation, and 9 d for data and sample collection. The first 4 d of the collection were used to evaluate behavioral data (milking frequency, feeding behavior, and standing and lying behavior) and ruminal pH. Subsequently, a rest day was provided and the last 4 days were used to evaluate ruminal fermentation and apparent total tract digestibility. All 8-d were used for measurement of DMI and milk yield. Cows fed the H-AMS consumed 3.5 kg less PMR while consuming 4.2 kg/d more AMS concentrate, but total DMI (PMR+AMS) was not affected by treatments averaging 27.3 kg/d. Although cows fed H-AMS had greater concentrate intake, they also had greater variability for AMS concentrate intake among days (0.85 vs. 0.25 kg/d, respectively). The number of PMR meals, and PMR eating behavior were not affected by the PMR or AMS treatments. Feeding H-AMS did not affect milking frequency, but tended to increase milk yield by 1.25 kg/d relative to L-AMS. Likewise, cows fed the L-FOR tended to have greater milk yield relative to H-FOR (39.3 vs 37.9 kg/d), but had greater holding area time. Minimum ruminal pH tended to be lower for cows fed a L-FOR compared to cows fed H-FOR but was not affected by the AMS treatment. When fed the L-FOR, feeding the H-AMS increased total short-chain fatty acid concentration in the rumen relative to cows fed L-AMS, while the response for H-FOR was not affected by the AMS concentrate. These data suggest that feeding H-AMS may improve milk yield but also increases the day-to-day variability in AMS concentrate consumption. Feeding a L-FOR PMR may increase milk yield without affecting variability in AMS concentrate consumption; however, it may reduce ruminal pH and increase holding area time relative to feeding a H-FOR PMR.
For the complete document please visit http://www.saskmilk.ca/images/pdfs/Research/15_Feb_2018_AMS.pdf