Hempseed cake as a protein feed for growing cattle

Sammanfattning: Protein feeds used by Swedish animal producer's origin from different parts of the world. Protein feeds produced in Sweden are among all rape seed cake, peas and field bean. In addition soybean meal is imported and used as a high quality protein feed. Since 2003 there is also a new protein feed available on the market produced from hemp, Cannabis sativa, which can be grown in arable regions throughout Sweden. Hempseed cake, a by-product of the oil processing industry, provides a rich source of protein for the animal feed sector. Nutritionally, hempseed cake is equivalent to rape seed cake, potentially making it a viable alternative to imported soybean meal. This master thesis included two different trials with the aim to investigate hempseed cake as a protein feed for growing dairy cattle in comparison to feeding soybean meal. In one of the trials, there were 55 bull calves while the other trial consisted of 51 steers. The calves weighted 96 kg at the start of the experiment and were used in the trial until an average weight of 237 kg, whereas the steers initially weighed 366 kg (Swedish Holstein) and 400 kg (Swedish Red Cattle) and were studied until they had reached targeted live weights for slaughter. In both of the trials the animals were divided into two groups where one group was provided hempseed cake and the other group soybean meal as a protein supplement. The steers were also divided in two groups according to their live weights at slaughter, 600 and 650 kg, and in two groups according to breed, Swedish Holstein and Swedish Red Cattle. In both trials the effects on feed intake, daily weight gain and faecal traits were investigated. In the steers also the effects on carcass traits were studied. A basal diet consisting of barley and grass silage at a 60:40 ratio was fed ad libitum. Basal diet was supplemented by top dressing with either hempseed cake or a soybean/barley concentrate. Supplements were balanced to provide equivalent crude protein content. Animal daily feed intakes were calculated weekly and animal daily weight gain was calculated based on by-weekly weights. In faecal matter, number of long particles (>1 cm), number of kernels, consistency, pH and dry matter content were analyzed. At slaughter of the steers, carcass weights, conformation and fatness scores were recorded. Trim fat, bones and retail cuts from the right hind quarter were also weighed from every steer. The content of neutral detergent fibre (NDF) was 434 g kg-1 of dry matter in hempseed cake and 160g kg-1 of dry matter in the mixture of soybean meal and barley. This resulted in both trials of a higher NDF intake in animals fed hempseed cake compared to animals fed soybean meal. In the trial with the calves the dry matter intake and concurrent gross energy intake were higher in those animals given hempseed cake but there was no difference in feed consumption in the trial with the steers. No effect of protein feed on daily weight gain was found. The daily gain was on average 1310 g for the calves and 1220 g for the steers. Calves fed hempseed cake had, in comparison with animals fed soybean meal, higher feed intakes in combination with similar growth resulting in worse feed conversions. The faecal matter from steers fed hempseed cake was of a higher dry matter content and a firmer texture in comparison with faecal matter from steers fed soybean meal. In addition, in both trials, the faecal matter contained fewer long particles (>1 cm) when the animals were given hempseed cake in comparison to animals given soybean meal. The number of long particles (>1 cm) and the percentage of kernels in faeces, on a dry weight basis, were less for calves fed hempseed cake than for calves fed soybean meal. The group of steers given soybean meal and had a target slaughter weight at 650 kg live weight required a longer finishing period to reach the targeted weight compared to steers fed hempseed cake. However, dressing percentage was higher for steers fed soybean meal than for steers fed hempseed cake. Carcasses from steers slaughtered at a live weight of 650 kg had a higher fatness score than steers slaughtered at a live weight of 600 kg. The conformation score of Swedish Red Cattle was on average 0.8 classes better than the conformation score for Swedish Holstein. No further effects of breed or live weight at slaughter were found in the study. The higher NDF intakes in animals fed hempseed cake compared to animals fed soybean meal in combination with the lower numbers of long particles, higher dry matter content and firmer consistency in faeces indicates that feeding hempseed cake resulted in a better rumen function. The loose consistency and high numbers of particles from steers fed soybean meal indicates the feed is passing through the rumen too fast and resulting in a decreased degradation of the feed particles and more long particles remained in the faecal matter. A too fast rate of passage also results in a lower dry matter which could be seen in the faecal matter from the steers fed soybean meal. The conclusion from the two trials is that hempseed cake as a protein feed instead of soybean meal to intensively fed growing cattle, results in similar weight gain and carcass traits as well as an improved rumen function, due to the higher content of fibres in hempseed cake in comparison to soybean meal.