Utilization of Palm Kernel Cake as a Ruminant Feed for Animal: A Review

The study investigated the effect of in-feed administration of dried thyme leaf and celery seed mixture (at 1 : 1 DM basis) compared with salinomycin ionophore on milk production and milk nutritive value of Barki ewes. Thirty ewes (37.5 ± 1.8 kg), divided into 3 treatment groups, were fed: (1) a complete control diet comprising concentrates and fodder maize (Zea mays L.) at 60 : 40 dry matter basis, (2) the control diet plus 20 g of thyme and celery mixture supplementation and (3) the control diet supplemented with 1 g of salinomycin per ewe daily for 90 days. Inclusion of thyme–celery treatment increased (P < 0.05) weight gain, average daily gain, milk yield, milk component yields, and feed efficiency, without affecting milk composition. In addition, the thyme–celery treatment enhanced (P < 0.05) nutrient intake and digestibility, total ruminal volatile fatty acids, branched chain fatty acids, and acetate proportions and decreased ammonia-N concentration. Thyme–celery treatment increased (P < 0.05) serum glucose, thyroxine, and glutamate-pyruvate transaminase concentrations. It is concluded that the thyme and celery mixture (1 : 1 DM basis) at 20 g per lactating ewe daily can replace the salinomycin ionophore. Enhanced feed utilization and lactational performance as well as milk nutritive value for human consumption were observed with the natural additive mixture supplementation.

Efforts directed toward enhancing animals’ productivity are focused on evaluating the effects of non-traditional feed additives that are safer than antibiotics, which have been banned because of their health hazards. Many studies used an amino acid that contributes to heme biosynthesis, known as 5-aminolevulinic acid (5-ALA), to promote the productivity of farm animals. However, these studies demonstrate inconsistent results. In order to develop a clear understanding of the effects of 5-ALA in farm animals, we comprehensively searched PubMed and Web of Science for studies evaluating 5-ALA effects on the performance, iron status, and immune response of different farm animals. The search retrieved 1369 publications, out of which 16 trials were relevant. The 5-ALA-relevant data and methodological attributes of these trials were extracted/evaluated by two independent researchers, based on a set of defined criteria. Samples were comprised of pigs, chickens, and dairy cows. The 5-ALA doses ranged from 2 mg to 1 g/kg of feed, and treatment duration ranged from 10 to 142 days. Overall, 5-ALA improved iron status in most studies and increased white blood cells count in 3 out of 10 studies, in addition to improving animals’ cell-mediated immune response following immune stimulation with lipopolysaccharide. Inconsistent findings were reported for growth performance and egg production; however, a combination of 10 mg/kg of 5-ALA with 500 mg/kg of vitamin C promoted the highest egg production. In addition, 5-ALA improved milk protein concentration. In conclusion, 5-ALA can enhance farm animals’ iron status and immune response; however, the heterogeneity of the reviewed studies limits the generalizability of the findings. Standard procedures and outcome measures are needed to confirm the benefits of 5-ALA. Attention should also be paid to any adverse effects.