Fodder beet and kale forage crops are an important tool for wintering in the south. Fodder beet bulbs are low in crude protein, fibre, phosphorus and calcium and usually make up a large proportion of fodder beet diets, meaning recommended daily intake of these nutrients may not be supplied. This can reduce animal production and impair animal health. Increasingly farmers were concerned about poorer than expected performance after calving, following fodder beet feeding. Issues included lower than expected milk production based on body condition score (BCS) at calving and levels of feeding in early lactation, the unknown impact of fodder beet feeding on lifetime performance, reproductive performance, and links with metabolic disease.
To investigate this, a winter feeding trial was conducted in winter 2017 at the Southern Dairy Hub to compare winter diets of fodder beet or kale with baleage, each at two allocation rates: ‘target’ and ‘high’.
Target = offered a maximum of 70% of the diet as crop and used the DairyNZ winter crop allocation calculator to determine feed required to achieve sufficient BCS gain to meet a BCS target at 5 at calving.
High = offered at least 80% of the total diet as crop and crop was offered ad libitum with baleage.
Diets with FB were lower in fibre, phosphorus, sulphur and calcium, but had higher metabolisable energy and sugars, compared with kale diets.
Average body condition score gain before calving was similar for fodder beet and kale cows.
Crop type had a greater impact on cow performance than allocation rate.
Cows wintered on fodder beet had better reproductive performance and great average milk solids, fat and protein yield than cows wintered on kale.
Fodder beet cows had lower blood urea and phosphate levels, and higher magnesium levels while on crop and pre-calving, compared to kale cows.
FB cows spent less time lying and took more daily steps than kale cows.
Animal behaviour differed in fair and adverse weather conditions. In adverse weather conditions, lying time was reduced and steps increased.