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African leaf meal let pigs grow

Alternative ingredients for animal diets are constantly tested. One of them is Vachellia tortilis leaf meal, made from a native African tree.

Leguminous tree forages, such as Vachellia, formerly subgenus Acacia are important in livestock production since they can be used as protein sources. These leguminous tree leaves contain high amounts of crude protein of almost 218 g/kg DM and favourable mineral concentration. Low levels of leguminous leaf meal diets can decrease the harmful effects of saturated fatty acids of pork meat due to the presence of polyphenolic compounds and natural antioxidants. The trees are abundant in the dry zones of the African continent.

Average daily feed intake decreased quadratically with increasing inclusion of V. tortilis leaf meal. Photo: Koos Groenewold
Average daily feed intake decreased quadratically with increasing inclusion of V. tortilis leaf meal. Photo: Koos Groenewold

Diet changes need adaption time

Although the use of Vachellia leaves as feed sources for pigs has been reported earlier the adaptation of pigs to these diets has not been assessed. A South African research team therefore looked at Vachellia tortilis leaf meal inclusion in the diet of fattening pigs and recorded the adaptation periods. It was hypothesised that the amount of proanthocyanidins and fibre present in Vachellia leaf meals may prolong the adaptation phase. To further test this, a total of 48 clinically healthy male Large White × Landrace male pigs with a mean (± SD) body weight of 63.8 ± 3.28 kg aged 14 weeks were used. Pigs were assigned to individual pens in a completely randomised design and allotted to each of 6 experimental diets which contained 0, 30, 60, 90, 120 and 150 g/kg DM of V. tortilis leaf meal (Table 1). The adaptation period was measured daily while average daily feed intake (ADFI) and average daily gain (ADG) were calculated weekly with gain: feed ratio (G: F) of pigs.

Higher inclusion level, longer adaptation

Average daily feed intake decreased quadratically with increasing inclusion of V. tortilis leaf meal. There was a positive linear relationship in ADG with increasing inclusion level of V. tortilis leaf meal Increasing inclusion levels of V. tortilis leaf meal displayed a quadratic increase in G: F ratio of pigs (Figure 1). Inclusion levels of V. tortilis leaf meal had a linear increase on the adaptation period of pigs. Inclusion level of V. tortilis leaf meal diets increases the adaptation period of pigs. As the leaf meal inclusion increased by 1 g/kg DM, the adaptation period increased by 0.027 days. Variation of feed intake, expressed as a coefficient of variation of feed intake, increased linearly with increasing inclusion level of V. tortilis leaf meal.

Conclusions

Performance characteristics of pigs were influenced by increasing inclusions of Vachellia tortilis leaf meal diets. Increasing inclusion level of V. tortilis leaf meal diets caused a positive relationship in the adaptation period of pigs. As the leaf meal inclusion increased by 1 g/kg DM, the adaptation period increased by 0.027 days. In addition, V. tortilis leaf meal inclusion also increased the variation of feed intake across the diets. It is, however, necessary to investigate the behaviour of pigs fed on V. tortilis leaf meal inclusion and the extent of the adaptation period even in sows so that V. tortilis leaf meals can also be used in both sows and boar diets.

The full paper can be read here.