Effects of different dietary inclusion levels of macadamia oil cake on growth performance and carcass characteristics in South African mutton merino lambs.

Growth performance and carcass characteristics of South African mutton merino fed graded levels of macadamia oil cake were assessed. A total of 60 South African mutton merino lambs were used in the experiment (initial live weight 25.0 ± 0.45 kg). Five diets with different inclusion levels of macadamia oil cake (MOC) were formulated: T1 (0% MOC, control), T2 (5% MOC), T3 (10% MOC), T4 (15% MOC) and T5 (20% MOC). Effects of inclusion level of MOC on average daily gain (ADG) and average daily feed intake (ADFI) were not significant (P > 0.05). Effects of inclusion levels of MOC on feed conversion ratio (FCR) of sheep were significant (P < 0.05). Highest proportion (71.2%) of sheep in the study had a carcass fat classification of 2, followed by a proportion of 17.3% sheep with a carcass fat classification of 3 and lastly 11.5% sheep had carcass fat classification of 4. Warm and cold carcass mass, chest circumference, carcass length and dressing percentage were higher in sheep fed on 5% MOC compared to other treatment diets (0, 10, 15 and 20% MOC) (P < 0.05). Fat rib eye had a greater area in sheep fed on 5% MOC (P < 0.05). It was concluded that 5% MOC provided the best results in terms of carcass characteristic measurements in sheep.

The potential of replacing soyabean oil cake with macadamia oil cake in broiler diets.

A study was conducted to evaluate the potential of macadamia oil cake (MOC) as a replacement of soyabean oil cake (SOC) in Ross broiler diets. The 600 1-day-old male broiler chicks were randomly blocked into 30 equal-weight groups of 20 chicks. For each growth phase, basal and summit diets were blended in various proportions (100 % SOC and 0 % MOC, 75 % SOC and 25 % MOC, 50 % SOC and 50 % MOC, 25 % SOC and 75 % MOC, and 0 % SOC and 100 % MOC) to form five treatments. The diet with 100 % MOC had the least feed intake, final body weight and weight gain compared to other diets (P < 0.05). The increased abdominal fat of broilers fed more than 50 % levels of MOC could be due to high levels of lipids in MOC compared to soyabean oil cake. The feed conversion ratio did not differ significantly for most of the treatments (P > 0.05). It was concluded that the threshold of 25 % MOC can replace soybean oil cake meal in the diets of broiler provided that this alternative feed ingredient is readily available at an affordable cost.

Responses of male broiler chickens from two genetic groups to different stocking densities in a semi-arid subtropical environment.

The effects of stocking densities of 30, 35, 40 and 45 kg body weight (BW)/m(2) on the growth performance of Ross 308 and Hubbard broiler chickens were studied in a 49-day production period. Ross 308 was superior to Hubbard in weight gain and market weight and consumed more feed (p<0.05) but the strains did not differ significantly in feed efficiency, mortality rate and abdominal fatness. Overall, birds raised at stocking densities of 30, 35 and 40 kg BW/m(2) performed equally well in weight gain, feed consumption and 49-day live weight and outperformed those raised at 45 kg BW/m(2) (p<0.05). It is suggested that for profitable broiler production under tropical conditions Ross 308 and stocking density of 40 kg BW/m(2) be considered.

Effects of strain and different skip-a-day feed restriction periods on the growth performance of broiler chickens.

The effects of 6, 10 and 14 days of skip-a-day feed removal during the starter and grower periods on the growth performance of Ross 308 and Hubbard broiler chickens were studied in a 49-day production period. Ross 308 was superior to Hubbard in weight gain, market weight and feed utilization but consumed more feed, deposited more abdominal fat and had a higher mortality rate. Overall, feed removal improved feed efficiency, had insignificant effects on abdominal fatness and mortality rate and reduced feed intake, weight gain and market weight. On each restricted-feeding regime, the birds gained as much weight as their fully fed counterparts during the period of resumed full feeding but were unable to compensate fully for the weight loss and were lighter at the end of the trial. It is suggested that for profitable broiler production under tropical conditions, Ross 308 and skip-a-day feed removal for less than 6 days from 7 to 17 days of age be considered.