Abstract
Two hundred sixteen crossbred ($Landrace{\times}Yorkshire$) castrates with an average weight of $7.4{\pm}0.3kg$ were used in a $3{\times}3$ factorial treatment array. The treatments were three levels of Herb mixture (HM; 0, 0.40 and 0.80 g/kg BW/day) and three levels of dietary nutrient (17.30% CP, Level-1; 17.90% CP, Level-2; and 18.50% CP, Level-3). The influence of HM intake and nutrient level on growth performance and ADG in 0.40- and 0.80-HM pigs increased significantly (p<0.01) as nutritional level was elevated. Although very little enhancement of ADG was observed at Level-1, peak ADG occurred in 0.8-HM treated pigs at Level-3. Feeding of 0.80 g HM/kg/d to pigs consuming Level-1 diet resulted in a 8.7% increase in ADG compared with control pigs, whereas the increase in ADG as a result of 0.80-HM with Level-3 treatment was 39%. ADFI in Level-2 pigs improved linearly (p<0.01) as HM level was increased. Treatment with HM resulted in a 12.0% increase ranging 4.7 to 20% in the ADFI compared with respective controls. ADFI at all nutritional level was significantly higher in 0.80-HM pigs (p<0.02). F/G in Level-2 pigs improved significantly as HM was fed (p<0.01), and in HM-0.80 pigs was also significantly improved as nutritional level was increased (p<0.05). Pigs fed HM had higher bone mineral density (BMD) at Level-1, longer dorsal spine length (DSL) at level-2 (p<0.05) than pigs fed basal diets. Pigs fed HM tended to higher BMD and DSL than those fed basal diets. The level of GH secretion declined with age. There was no difference between treatments (p>0.05) in the serum growth hormone at the same age. The GH was higher in pigs fed HM than those fed basal diets and increased in all pigs after 2wks feeding. A positive effect of added Herb-Mix on growth performance in weaned pigs was demonstrated by measuring the serum growth hormone, bone mineral density and length of dorsal spine.