Summaries of ongoing research 2021

A2 genetics and production and fertility of organic Holstein dairy cows

Holstein cows (n = 1, 982) from 13 dairy herds across the Midwest and Northeast were genomic tested with CLARIFIDE® Plus for A2 status. Two-hundred fourteen cows were A1A1 (11%), 848 cows were A1A2 (43%) and 920 cows were A2A2 (46%). Milk production was not different for A1A1 (58 lb/day), A1A2 (60 lb/day), and A2A2 (61 lb/day) cows.  Survival to 2nd lactation was 83% for A1A1 cows, 97% for A1A2 cows, and 95% for A2A2 cows. There were no differences in production and fertility with regard to A1 or A2 genotype in organic dairy herds.  Survival may be biased against the A1 genotype which is indicated by lower survival rates in first lactation. 

Fatty acid profiles of Holstein, Grazecross and ProCROSS cows in an organic and low-input conventional dairy herd 

The fatty acid (FA) profiles of milk vary due to nutrition and breed of dairy cattle. Milk that is higher in short-chain FA is of interest to consumers who are concerned about their health. The objective of this study was to compare FA profiles from DHIA of Holstein cows (HO; n = 54) with Grazecross crossbred cows (n = 60) composed of the Normande, Jersey, and Viking Red breeds and ProCROSS crossbred cows (n = 120) composed of the Montbéliarde, Viking Red, and HO breeds. Total FA, De Novo FA (C4 to C14), Mixed FA (C16, C16:1, C17), Preformed FA (≥ C18) concentrations were provided by Minnesota DHIA (Buffalo, MN) from monthly DHIA test day.  Milk fat from Grazecross cows had +12.2% more Total FA than the other breed groups. Dairy producers interested in marketing milk with higher FA concentrations may implement the Grazecross 3-breed rotational crossbreeding system. 

Response to ad libitum milk allowance by crossbred dairy and dairy-beef calves in an automated feeding system 

The objective of this study was to determine growth and milk consumption traits of Pure Holstein, ProCROSS, Grazecross, and Limousin crossbred dairy and beef calves fed alternative milk allowances in an automated group feeding system.  Calves were introduced to the Holm & Laue HL 100 calf feeder (Holm & Laue GmbH & Co KG, Westerronfeld, Germany) at 5 d.  As expected, AL calves had larger milk cost ($193.66) than the 8L calves ($138.82). Limousin crossbred bull calves had the greatest (2.42 lb/dday) average daily gain (ADG) and Holstein heifer calves had the least (2.11 lb/day) ADG. Calves fed AL had a greater ADG than calves fed 8L (2.49 lb/day versus 1.94 lb/day, respectively). The results from this study show advantages to feeding calves AL or 8L with an automated feeding system depending on breed.