Abstract

Feeding birdsfoot trefoil (lotus, Lotus corniculatus) to dairy cows increases milk solids production and reduces methane production relative to ryegrass pasture. This study has measured the affect of lotus and lotus condensed tannins (CT) on milk protein and lipid composition. The trial involved 32 Friesian dairy cows offered either good quality perennial ryegrass pasture or lotus. Half of the cows given each diet were drenched with polyethylene glycol (PEG) to inactivate the CT. A daily milk sample was collected from all cows prior to and towards the end of the treatment period. Gross milk fat and milk protein concentrations were similar for cows fed lotus or ryegrass. Neither feed, nor CT affected individual proteins in the milk with the exception of lactoferrin (Lf) where the CT in lotus increased concentrations (138 vs 76 mg/l; P < 0.01). Forage type affected the composition of fatty acids (FA) in the milk with cows gazing lotus having higher concentrations of de novo synthesised (C4:0-C15:0; 28.3% vs 26.7%; P < 0.01) and lower concentrations of pre-formed (C17:0 and longer; 34.5% vs 39.0%; P < 0.05) FA than those grazing ryegrass. The CT in lotus appeared to affect ruminal biohydrogenation of FA, decreasing the concentration of saturated FA in the milk fat, and increasing in the concentrations of the omega-3 FA (1.5% vs 1.1%; P < 0.01). Changes in the saturation and proportions of FA may affect processing characteristics and functionality of milk from cows fed lotus. CT in lotus may also provide potential new avenues for increasing milk value on-farm. KEYWORDS: detailed milk composition; Lotus corniculatus; condensed tannins.

S-A, Turner, GC Waghorn, SL Woodward, and NA Thomson

Proceedings of the New Zealand Society of Animal Production, Volume 65, Christchurch, 283-289, 2005