P. Isherwood

Supplementation of cattle fed tropical grasses with microalgae increases microbial protein production and average daily gain

A series of 3 experiments were conducted to evaluate the use of microalgae as supplements for ruminants consuming low-CP tropical grasses. In Exp. 1, the chemical composition and in vitro protein degradability of 9 algae species and 4 protein supplements were determined. In Exp. 2, rumen function and microbial protein (MCP) production were determined in steers fed speargrass hay alone or supplemented with , , , or cottonseed meal (CSM). In Exp. 3, DMI and ADG were determined in steers fed speargrass hay alone or supplemented with increasing amounts of NPN (urea combined with ammonia sulfate), CSM, or . In Exp. 1, the CP content of and (675 and 580 g/kg DM) was highest among the algae species and higher than the other protein supplements evaluated, and sp. had the highest crude lipid (CL) content (198 g/kg DM). In Exp. 2, supplementation increased speargrass hay intake, the efficiency of MCP production, the fractional outflow rate of digesta from the rumen, the concentration of NHN, and the molar proportion of branched-chain fatty acids in the rumen fluid of steers above all other treatments. acceptance by steers was low and this resulted in no significant difference to unsupplemented steers for all parameters measured for this algae supplement. In Exp. 3, ADG linearly increased with increasing supplementary N intake from both and NPN, with no difference between the 2 supplements. In contrast, ADG quadratically increased with increasing supplementary N intake from CSM. It was concluded that and may potentially be used as protein sources for cattle grazing low-CP pastures.

Effect of treatment of cocoa-pods with Aspergillus niger on liveweight gain and cocoa-pod intake of Bali (Bos sondaicus) cattle in South-East Sulawesi.

Cocoa-pods, a by-product of the cocoa industry, could potentially be used as a feed resource for ruminants in eastern Indonesia. However, little is known regarding the optimal amount to be included in the diet or the effect of treatment with Aspergillus niger on cocoa-pod quality. In this experiment the effect of rate of inclusion (0 or 10 g DM/kg liveweight.day or ad libitum) of A. niger-treated or untreated cocoa-pods in the diet on intake and liveweight gain of Bali cattle (Bos sondaicus) was investigated. Ad libitum intake of cocoa-pods was greater when they were treated with A. niger (17.1 ± 0.07 g DM/kg liveweight.day; mean ± s.e.m.) compared with untreated cocoa-pods (13.9 ± 0.19 g DM/kg liveweight.day) when offered as the sole component of the diet. The digestibility of A. niger-treated cocoa-pods (448.9 ± 23.7 g/kg) was not different to untreated cocoa-pods (422.9 ± 13.9 g/kg) when fed ad libitum, which was lower than native grass (527.2 ± 10.7 g/kg). Animals offered A. niger-treated cocoa-pods lost less liveweight than animals offered untreated cocoa-pods when offered ad libitum (–0.104 ± 0.02 and –0.280 ± 0.02 kg/day, respectively), and grew faster when included in the diet at 10 g DM/kg liveweight.day (0.233 ± 0.02 and 0.129 ± 0.02 kg/day, respectively). In conclusion, in areas where cocoa plantations exist, cocoa-pods may be a useful feed resource for ruminants when fed at low levels of inclusion in the diet. The treatment of cocoa-pods with A. niger will result in increased liveweight gain. However, it is unlikely such treatments will be adopted by small-holder farmers due to the increased requirements for inputs, such as time, labour, funds, equipment, and technical skills.