The effect of lucerne (Medicago sativa) hay quality on milk production and composition of Jersey cows
The influence of lucerne hay quality on the milk production potential and milk composition of Jersey cows was investigated. Three different grades of lucerne hay (Prime, Grade 1, Grade 2; selected according to the New Lucerne Quality Index) were included in a total mixed ration (TMR) and fed to lactating cows. The three dietary treatments consisted of the same basal diet (53% lucerne hay, 7% wheat straw and 40% concentrate), differing only with respect to the lucerne hay quality. Fifty-seven lactating Jersey cows (389 ± 39.07 kg) were selected and blocked according to production potential (milk production, days in lactation, as well as lactation number) and randomly allocated to each of the dietary treatments (n = 19 animals per treatment). After a dietary adaptation period of 14 days, each treatment received their respective diets for the remaining period of 54 days. Average dry matter intake (DMI) and individual milk production was measured on a daily basis and production parameters were calculated accordingly. Milk composition samples were collected every second week. Grade 2 lucerne hay significantly decreased the voluntary DMI of the cows. However, the Prime lucerne hay significantly increased the metabolizable energy intake (MEI), as well as both the protein and milk urea nitrogen (MUN) content of the Jersey milk, compared to the Grade 1 and Grade 2 treatments. In contrast, the efficiency with which ME is utilized for milk production was significantly decreased following Prime lucerne hay inclusion. Milk yield as such was not affected by dietary treatment. Results of the present study seem to indicate that lucerne hay quality does affect the production performance, milk composition and efficiency of energy utilized for milk production purposes of Jersey cows.
Keywords: Dairy, index, lactation, nutrient, performance, roughage, TMR