An investigation into reduced milk production following dietary alteration on an Irish dairy farm

Nutritional management of the dairy cow has significant influence on health, production and reproduction particularly around parturition and early lactation [9,7]. Monitoring nutritional status of the transition cow involves an assessment of nutritional inputs, body condition score changes, milk production performance, the incidence of production diseases, and blood parameters for mineral status and energy balance. A holistic preventative approach incorporating these elements has been outlined previously [7]. Using this approach, if shortfalls (differences between farm targets and performance) in cow health or production are identified, an investigation into feeding management and dietary composition is indicated to assess nutritional status in greater detail. Several nutritional modelling software packages are available to aid advisors in designing appropriate diets for specific performance criteria [1,8]. The accuracy of predictions made by such programmes depends on how accurately data entered by the advisor reflects the on-farm situation. There are a large number of on-farm variables that make accurate dietary evaluation and formulation challenging. This report describes an investigation into nutritional management of transition cows on an Irish dairy farm and an unexpected reduction in production performance following dietary alteration.A visit was conducted to an 80-cow dairy herd on January 29, 2010 to initiate nutritional monitoring. The 2009-2010 calving pattern and lactation status of each cow on the day of the visit is shown in Figure 1. Lactating cows (n = 56) were housed together and fed a single total mixed ration (TMR) ad-libitum plus home blended concentrates in-parlour at two rates for early (n = 26; average days in milk 44; range 3 - 110) and late lactation (n = 30; average days in milk 318; range 150 - 704) cows respectively. Dry cows (n = 20) were housed separately and fed a separate TMR. Details of all diets were gathered from farmer interview a