Hempseed cake as a protein feed for ruminants

• Increasing the use of locally produced protein feeds in ruminant production systems in northern Europe would be a valuable development. Hemp (Cannabis sativa L.) can be cultivated at high latitudes and cold-pressing the seeds to extract the oil produces a residue, hempseed cake (HC), with a high protein content. The overall aim of the studies presented in this thesis was to investigate the possibilities of using HC as a protein feed for ruminants. The in vitro gas production technique was developed further in order to estimate rumen protein degradation; the effective protein degradation (EPD) of HC determined by this method was low (0.33). When calculated from in situ crude protein (CP) disappearance, HC had a high EPD value (0.71-0.84) and a low in vitro intestinal digestibility (0.18-0.31) for the rumen undegradable protein (RUP). Moist heat treatment could be used to shift the site of CP digestion from the rumen to the small intestine. The highest temperature considered, 130°C, was associated with the largest amount of RUP and rumen undegraded amino acids with the highest intestinal digestibility. A high proportion of the neutral detergent fibre in HC was indigestible (0.85), which contributed to a low calculated metabolisable energy value (9.5 MJ/kg dry matter). Increasing the proportion of HC (0, 143, 233 or 318 g/kg dry matter) in the diet of dairy cows produced effects on the yields of milk, energy corrected milk and milk protein, fat and lactose that could be described by quadratic functions; the highest production was achieved by cows fed the diet containing 143 g HC/kg dry matter. There were linear decreases in the concentration of milk fat and protein and CP efficiency (milk protein/CP intake), and a linear increase in milk urea, with increasing proportions of HC. Supplementing barley-based diets with peas or rapeseed cake improved the growth performance of lambs, but inclusion of HC resulted in an average daily gain similar to that achieved with the control diet containing no protein supplement. The results from the studies underlying this thesis indicate that the nutritional value of HC will limit its use as a protein feed for ruminants.

Ämnesord

LANTBRUKSVETENSKAPER  -- Husdjursvetenskap -- Husdjursvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Animal and Dairy Sience -- Animal and Dairy Science. (hsv//eng)

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