Strategic nutritional enhancement of cow-calf performance in South Central Coastal Vietnam

The increasing demand for beef in Vietnam has opened up great opportunities for farmers to improve their income base. However, some deficiencies in animal nutrition and management need to be addressed before these opportunities are captured. Therefore, the aim of this thesis was to improve the productivity of the cow-calf system in the South Central Coastal (SCC) area of Vietnam through: i) identifying the characteristics and management practices in Nhon Khanh commune; and ii) determining the impact of supplementing cows with concentrate 3 months pre- and post-partum on liveweight (LW), body condition score (BCS) and calving to conception interval (CCI). Structured interviews of 103 smallholder farmers, who owned from 1 to 4 cows, were utilised to characterise management practices of the cow-calf production system, coupled with an evaluation of BCS and reproductive performance of 475 cows in Nhon Khanh from January to July 2014. In addition, 165 calves (0-6 months old) were weighed and body length and chest girth measured monthly to assess growth rate. Baseline results from this characterisation phase of the study indicated that feed shortage was considered by farmers to be the biggest constraint to cow-calf production in Nhon Khanh commune, as evidenced by over-grazing. Approximately 50-70% of households faced pronounced feed shortages, particularly in December and January. Cow body condition score was negatively correlated with CI and daily duration of grazing - cows spending more time grazing had lower BCS and longer CI compared to cows grazing for shorter periods. Subjective visual assessment of the physical body conformation of calves was adjudged to be the major determinant of sale price. Nearly all surveyed farmers fed concentrates, e.g., maize, rice bran, and cassava powder, and cooking was the most common method of preparing the concentrate. In order to improve the efficiency of use of the traditionally cooked concentrate, and to boost pre- and post-partum cow performance, an experimental phase utilising improved supplementary diets from local feed resources was the next logical step of the study. Twenty crossbred cows (initial average LW of 366 ¬¨¬± 53 kg and parity ‚Äöv¢¬ß5) in their third trimester of pregnancy were randomly allocated into one of four pre- and post-partum supplementation regimens: 1) Control diet only; 2) Control diet pre-partum and improved diet post-partum; 3) Improved diet pre-partum and control diet post-partum; and 4) Improved diets pre- and post-partum. The control diet was a mixture of maize powder and rice bran offered at 0.25% of body weight (BW) pre-partum (90 days) and 0.35% of BW post-partum (90 days). The improved diet was a mixture of maize powder (20%), rice bran (20%), peanut cake (20%) and cassava meal (39%) offered at 0.35% of BW pre-partum and 0.5% of BW post-partum. All treatment groups were fed a basal diet of 30% King grass and 70% rice straw of DM at 2% of their bodyweight. Feeding of the improved diet had a significant (P<0.05) positive effect on calf LW, body length and chest girth at birth, but not at 90 days of age. There was a significant effect of diet on the average cow BW (P<0.01), BCS (P<0.01) and CCI (P<0.0001). However, there was insufficient evidence for the effect of the timing of feeding the concentrate (pre- or post-partum) on cow LW, BCS and cow fertility.The CCI was longer for cows fed the control diet (212 days) than for cows fed the improved diet pre-partum (176 days). Cows fed the improved diet post-partum had the shortest CCI (144.5 days). Post-partum supplementation improved cow-calf performance and induced early cyclicity, thereby shortening CCI and enhancing overall reproductive performance under on-farm conditions. There are several implications of this research for beef production in Vietnam. Firstly, from the surveys, it found out some problems of cow-calf system in Vietnam such as inadequate feeding, especially in feed shortages period, poor grazing management, and lack of calf management. Secondly, this research pointed out that the efficient of cow-calf system can be increased if the cow-calf management and feeding system are improved. In addition, cow's BCS and reproductive performance could be improved by using improved diet post-partum for cows. In conclusion, the combined results from this study demonstrated the opportunity for smallholder farmers to increase the productivity of their cow-calf system through strategic supplementation with improved diets to mitigate against seasonal feed shortages and over-grazing of crowded communal land.