Abstract

The objective of this study was to use the Large Ruminant Nutrition System simulation (LRNS) model to evaluate inclusion of different proportions of fodder beet (FB) with several feed supplements to determine if these dietary combinations meet the nutrient requirements of dry cows and growing one-year-old (R1) heifers over winter. The LRNS simulations demonstrated deficiencies in Ca and P when diets contained 60 and 80% of FB, especially for dry cows up to 21 days before calving and in R1 heifers. When FB comprised 60-80% of the diet of R1 heifers, there was insufficient metabolisable protein to support maximum average daily gain and insufficient physically effective neutral detergent fibre (peNDF) in diets containing over 60% FB. Diets containing more than 40% FB had a negative rumen degraded protein balance (RDPB) and an excess non-fibre carbohydrate (NFC) concentration. Recommendations based on this modelling are for a maximum of 60% FB in diets and forage supplements must provide sufficient crude protein (CP) as well as supplementation of Ca for R1 heifers and dry cows up to 21 days before calving and P for both dry cows and R1 heifers.

A, Jonker, DE Dalley, RR Woods, RA Dynes, D Pacheco, MA Khan, JP Edwards, and KJ Hammond

New Zealand Journal of Animal Science and Production, Volume 82, Online, 39-44, 2022