M. T. Kidd

Dietary limitation of isoleucine and valine in diets based on maize, soybean meal, and meat and bone meal for broiler chickens

1. The dietary limitation of isoleucine (Ile) and valine (Val) was evaluated in broilers. Common diets were given to all broilers from 0 to 28 d of age. Experimental diets were provided from 28 to 42 d of age. 2. The experimental test diet was based primarily on maize, soybean meal, and meat and bone meal, and formulated to satisfy all nutrient recommendations with the exception of Ile and Val. 3. Diets were supplemented with L-Ile and L-Val at either 0·5 or 1·0 g kg−1 of diet, alone or in combination. A diet composed only of commercially available amino acids and formulated to satisfy all nutrient requirements served as a positive control. 4. Body weight gain was depressed by the test diet, but recovered to a weight similar to birds fed on the positive control when Val was added to the test diet either alone or in combination with Ile. Feed efficiency improved when Val and Ile were simultaneously supplemented. 5. Abdominal fat yield was reduced with the combined supplementation of Val and Ile. Breast meat yield appeared to be more sensitive to Ile supplementation than to Val. 6. The results suggest that live performance may be more sensitive to Val, while breast meat yield was maximised with Ile supplementation. However, their combination is required for optimised growth and meat yield.

Branched‐chain amino acids modulate the expression of hepatic fatty acid metabolism‐related genes in female broiler chickens

SCOPEnThe effects and roles of branched-chain amino acids (BCAAs) in hepatic fat metabolism are still unknown.nnnMETHODS AND RESULTSnHere, we used broiler chickens, in which lipogenesis occurs essentially in the liver as in human, to investigate the effects of three levels of BCAAs (control C, low L and exogenous supplemented diet L+S) on growth, carcass traits, immunity, and hepatic fat metabolism. Despite the same productive performance, immunity, and plasma BCAA levels between all groups, low BCAA levels significantly downregulated the hepatic expression of lipogenic genes particularly acetyl-CoA carboxylase alpha (ACCα) and stearoyl-coA desaturase 1 (p = 0.0036 and p = 0.0008, respectively) and upregulated the hepatic expression of mitochondrial β-oxidation- (uncoupling protein and NRF-1, p < 0.05) and dynamic-related genes (DNM1, p < 0.05). Concomitant with these changes, low BCAA levels increased the phosphorylation of AMP-activated protein kinase (AMPK)α(Thr172), ACCα(Ser79), and forkhead box protein O1 (FoxO1(Ser256)) and decreased the phosphorylation of mTOR(Ser2481) and P70 S6 kinase (Thr389). The mRNA abundance of the transcription factors SREBP1/2, peroxisome proliferator activated receptor alpha/beta, and FoxO1 were also increased in the liver of L group compared to the control.nnnCONCLUSIONnTogether our data indicate that low BCAA levels inhibit fatty acid synthesis and enhanced fatty acid β-oxidation in the liver of female broiler chickens and these effects were probably mediated through AMPK-mTOR-FoxO1 pathway.

Evaluation of carryover effects of dietary lysine intake by Cobb 500 broiler breeder hens

Two experiments were conducted to examine the progeny performance of broiler breeder (BB) hens fed diets differing in digestible lysine (dLys). A total of 240 Cobb 500 BB pullets and 40 cockerels, 20 wk of age, were used for each of 2 experiments. In experiment 1, treatment diets were fed from 35 to 45 wk of age. Treatment 1 and 2 diets were formulated with common feed ingredients and BB had dLys daily intakes of 1,200 (IDL-1,200) and 1,010 mg/hen per d (ID-1,010), respectively. Treatments 3 and 4 were composed of semipurified diets formulated to dLys intakes of 1,010 (SPL-1,010) and 600 mg/hen per d (SP-600), respectively. In experiment 1, chick weight at hatch was lower (P < 0.05) for those that came from the SP-600 and SPL-1,010-fed hens, but 42 and 56 d BW was similar for all treatments. Improvements (P < 0.10) in feed conversion ratio were seen at 42 and 56 d for chicks from ID-1,010-fed hens compared with IDL-1,200 hens. For experiment 2, diets were fed to BB hens from 24 to 42 wk of age. Treatment 1 was composed of corn-soybean meal and formulated to a dLys intake of 1,000 mg/hen per d (CS-1,000). Treatments 2, 3, and 4 had inclusion of 25% distillers dried grains with solubles (DDGS) with dLys intake levels of 1,000 (DDGS-1,000), 800 (DDGS-800), and 600 (DDGS-600) mg/hen per d, respectively. Progeny performance was evaluated from eggs collected at wk 26, 31, and 36. Chick hatch weight was similar for all 3 hatches. Chicks from 26-wk-old BB hens and fed DDGS-600 diets resulted in lower (P < 0.05) BW, carcass weight, and breast weight, and higher (P < 0.05) back half (drumsticks and thighs) yield, at 42 d of age. Growout studies performed on eggs laid during wk 31 and 36 revealed no effect on growth or carcass parameters. In conclusion, the results from experiments 1 and 2 may not be comparable, and therefore, the impact on progeny performance needs to be further evaluated.

Next-generation non-starch polysaccharide-degrading, multi-carbohydrase complex rich in xylanase and arabinofuranosidase to enhance broiler feed digestibility

&NA; This study was carried out to evaluate the effect of a multi‐carbohydrase complex (MCC) rich in xylanase (Xyl) and arabinofuranosidase (Abf) on overall broiler feed digestibility in broilers. Energy utilization and digestibility of dry matter (DM), organic matter (OM), protein, starch, fat, and insoluble and soluble fibers were measured using the mass‐balance method. The experiment was carried out on 120 broilers (3‐week‐old chickens). Broilers were distributed over 8 treatments to evaluate the effect of the dietary arabinoxylan content and nutrient density with and without MCC (Rovabio® Advance). The graded content of arabinoxylan (AX) was obtained using different raw materials (wheat, rye, barley, and dried distillers wheat). Diet‐energy density was modified with added fat. Measurements indicated that nutrient density and AX content had a significant effect on most digestibility parameters. Apparent metabolizable energy (AME) was significantly increased (265 kcal kg‐1) by MCC. The addition of MCC also resulted in significant improvement in the digestibility of all evaluated nutrients, with average improvements of 3.0, 3.3, 3.2, 3.0, 6.2, 2.9, 5.8, and 3.8% units for DM, OM, protein, starch, fat, insoluble and soluble fibers, and energy utilization, respectively. The interaction between MCC and diet composition was significant for the digestibility of OM, fat, protein, and energy. Nutrient digestibility and diet AME were negatively correlated with AX content (P < 0.001). However, the addition of MCC resulted in a reduction of this negative effect (P < 0.001). The AME of diets with and without the addition of MCC were successfully predicted by the diet digestible nutrient (i.e., starch, protein, fat, insoluble and soluble fibers) content with and without MCC (R2 = 0.87; RSD = 78 kcal kg‐1). This study confirms that the presence of AX in wheat‐based diets and wheat‐based diets with other cereals and cereal by‐products reduces nutrient digestibility in broiler chickens. Furthermore, the dietary addition of MCC, which is rich in Xyn and Abf, reduced deleterious effect of fiber and improved overall nutrient digestibility in broiler diets.

Effects of phytogenic additives on meat quality traits in broiler chickens1

Phytogenics have been reported to improve growth performances in farm animals and are thereby considered as potential key solutions for antibiotic-free livestock nutrition. Yet, their effects on meat quality are still not well defined; therefore, the aim of this study was to determine the effects of 5 experimental phytogenic additives (3 dietary and 2 water supplements) on growth and meat quality in broilers. One-day-old broiler chicks (n = 576) were assigned to 48 floor pens and divided into 6 treatments (Control, AV/HGP/16 premix [AVHGP], Superliv concentrate premix [SCP], bacteriostatic herbal growth promotor [BHGP], AV/SSL/12 [AVSSL], and Superliv Gold [SG]) in a complete randomized design (8 pens/treatment with 12 birds/pen, and 96 birds/group). Feed intake and BW were recorded, and birds were processed at 42 d to evaluate carcass traits. Breast muscle tissues were excised to determine stress- and antioxidant-related genes expression. Both AVSSL- and SG-treated broilers produced heavier (P < 0.05) slaughter weights compared with the control-fed broilers, whereas AVSSL supplementation decreased (P < 0.05) fat pad size and increased (P < 0.05) breast weights compared with the control-fed broilers. Although pH and a* values remained unchanged, L* was decreased (P < 0.05) in all treatment and b* was reduced (P < 0.05) in SG when compared with controls. The trained sensory panelists detected more (P < 0.05) green herb flavor in the breast meat from AVHGP than SCP, SG, and control birds. The expression of superoxide dismutase 2, extracellular signal-regulated kinase 1/2, and JNK gene was upregulated in AVHGP and BHGP compared with the control (P < 0.05). Together, these results indicated that phytogenic additives might improve meat quality of broilers through modulation of stress- and antioxidant-related pathways.