Ferris, Conrad P.Watson, SallyGordon, Alan WesleyBarley, Jason2022-02-242022-02-242022-02-03Ferris, C.P., Watson, S., Gordon, A.W. and Barley, J. (2022) ‘Physical and economic performance of dairy cows managed within contrasting grassland-based milk production systems over 3 successive lactations’, Journal of Dairy Science. American Dairy Science Association. doi:10.3168/jds.2021-20315.0022-03021525-3198https://doi.org/10.3168/jds.2021-20315Publication history: Accepted - 11 December 2021; Published online - 3 February 2022.A diverse range of grassland-based milk produc- tion systems are practiced on dairy farms in temper- ate regions, with systems differing in relation to the proportion of grazed grass, conserved forages and concentrates in diet, calving season, duration of hous- ing, cow genotype, and performance levels. The current study was conducted to examine performance within diverse grassland-based systems of milk production under experimental conditions. This study examined 4 milk production systems over 3 successive lactations (20 cows per system during each lactation). With win- ter calving-fully housed (WC-FH), Holstein cows were housed for the entire lactation and offered a complete diet consisting of grass silage, maize silage, and con- centrates [approximately 50% forage on a dry matter (DM) basis]. With winter calving-conventional (WC- Con), Holstein cows were housed and offered the same diet from calving until turnout (late March) as offered with WC-FH, and thereafter cows were given access to grazing and supplemented with 5.0 kg of concentrate/ cow daily. Two spring-calving systems were examined, the former involving Holstein cows (SC-H) and the lat- ter Jersey × Holstein crossbred cows (SC-J×H). Cows on these systems were offered a grass silage-concentrate mix (70% forage on a DM basis) until turnout (late February), and thereafter cows were given access to grazing supplemented with 1.0 kg of concentrate/ cow per day. The contributions of concentrates (3,080, 2,175, 722, and 760 kg of DM/cow per lactation), conserved forages (3,199, 1,556, 1,053, and 1,066 kg of DM/cow per lactation), and grazed grass (0, 2,041, 2,788, and 2,692 kg of DM/cow per lactation) to total DMI (6,362, 5,763, 4,563, and 4,473 kg of DM/cow per lactation) with WC-FH, WC-Con, SC-H, and SC-J×H, respectively, varied considerably. Similarly, milk yield (9,333, 8,443, 6,464, and 6,049 kg/cow per lactation), milk fat content (44.9, 43.3, 42.8, and 49.0 g/kg), and milk protein content (34.6, 34.9, 33.6, and 36.3 g/kg) differed between systems (WC-FH, WC-Con, SC-H, and SC-J×H, respectively). The higher milk yields with the WC systems reflect the greater concentrate inputs with these systems, whereas the greater milk fat and protein content with SC-J×H reflect the use of Jersey crossbred cows. Crossbred cows on SC-J×H produced a similar yield of milk solids as Holstein cows on SC-H. Cows on WC-FH ended the lactation with a greater body weight (BW) and body condition score than cows on any other treatment. While Jersey crossbred cows on SC-J×H had a lower BW than Holstein cows on SC-H, cows on these 2 systems were not different for any of the other BW, body condition score, or blood metabolite parameters examined. Cows on WC-FH had a greater interval from calving to conception, a greater mastitis incidence, and a greater locomotion score than cows on the spring calving systems. Whole-system stocking rates and annual milk outputs were calcu- lated as 2.99, 2.62, 2.48, and 2.50 cows/ha, and 25,706, 20,822, 15,289, and 14,564 kg of milk/ha, with each of WC-FH, WC-Con, SC-H, and SC-J×H, respectively. Gross margin per cow was highest with WC-Con, gross margin per hectare was highest with WC-FH, and gross margin per kilogram of milk was highest with SC-J×H. This study demonstrated that diverse grassland-based milk production systems are associated with very dif- ferent levels of performance when examined per cow and per hectare.en© 2022, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Received February 16, 2021. Accepted December 11, 2021. *Corresponding author: conrad.ferris@afbini.gov.ukdairy cattlefully housedJersey crossbredsgrassland systemsArticle