No abstract

There has been a dramatic increase in duck meat consumption. As a result, ducks are an interesting alternative type of livestock. Animal-based proteins such as fishmeal and animal by-products are valuable nutrients with high digestibility, but they are associated with cost fluctuations, pathogen contamination, and environmental impacts. Therefore, plant-based proteins are used, but they have the disadvantages of inappropriate amino acid profiles, anti-nutritional factors, and mycotoxin contamination. Insect meal contains favorable nutrients and low production costs and is environmentally friendly; however, there is a large number of insect species. Therefore, the purpose of this investigation is to screen insects for their potential use as a protein source in the duck diet. Insect meal with a high proportion of low-digestible components was shown to have low digestibility. Yellow mealworm larvae, giant mealworm larvae, lesser wax moth larvae, house fly larvae, mulberry silkworm pupae, and American cockroach nymph have the potential to be alternative protein sources for ducks. Insect meal has been widely studied and is used in animal nutrition to replace common protein sources that have several disadvantages and to promote sustainability in animal production. Two-step in vitro digestibility using crude enzyme extracts from digestive tracts of meat-type ducks (Cherry Valley) was performed on general protein sources and insect meals to compare the in vitro digestibility of organic matter (OMd) and crude protein (CPd). Variation in chemical components between different types of insect meal was found. A positive correlation was found between OMd and the ether extract composition in insect meal, whereas a negative correlation was shown between crude fiber and acid detergent fiber. Contrasting relationships were found between CPd and crude fiber and acid detergent fiber in insect meal. In conclusion, the yellow mealworm larvae (Tenebrio molitor), giant mealworm larvae (Zophobas morio), lesser wax moth larvae (Achroia grisella), house fly larvae (Musca domestica), mulberry silkworm pupae (Bombyx mori), and American cockroach nymph (Periplaneta americana) are potential protein sources for ducks based on OMd and CPd digestibility after screening with an in vitro digestibility technique.

ObjectiveComplete mtDNA D-loop sequences of four Thai indigenous chicken varieties, including Pra-dhu-hang-dam (PD), Leung-hang-khao (LK), Chee (CH), and Dang (DA) were explored for genetic diversity and relationships with their potential ancestor and possible associates to address chicken domestication in Thailand.MethodsA total of 220 complete mtDNA D-loop sequences of the four Thai indigenous chicken varieties were obtained by Sanger direct sequencing of polymerase chain reaction amplicons of 1,231 to 1,232 base pair in size. A neighbor-joining dendrogram was constructed with reference complete mtDNA D-loop sequences of Red Junglefowl (RJF) and those different chicken breeds available on National Center for Biotechnology Information database. Genetic diversity indices and neutrality test by Tajima’s D test were performed. Genetic differences both within and among populations were estimated using analysis of molecular variance (AMOVA). Pairwise fixation index (FST) was conducted to evaluated genetic relationships between these varieties.ResultsTwenty-three identified haplotypes were classified in six haplogroups (A–E and H) with the majority clustered in haplogroup A and B. Each variety was in multiple haplogroups with haplogroups A, B, D, and E being shared by all studied varieties. The averaged haplotype and nucleotide diversities were, respectively 0.8607 and 0.00579 with non-significant Tajima’s D values being observed in all populations. Haplogroup distribution was closely related to that of RJF particularly Gallus gallus gallus (G. g. gallus) and G. g. spadiceus. As denoted by AMOVA, the mean diversity was mostly due to within-population variation (90.53%) while between-population variation (9.47%) accounted for much less. By pairwise FST, LK was most closely related to DA (FST = 0.00879) while DA was farthest from CH (FST = 0.24882).ConclusionAll 4 Thai indigenous chickens are in close relationship with their potential ancestor, the RJF. A contribution of shared, multiple maternal lineages was in the nature of these varieties, which have been domesticated under neutral selection.

Heat stress is a life-threatening factor in commercial broilers raised in the tropics (e.g., Thailand) without temperature-controlled housing facilities. However, these temperature-controlled facilities are hardly affordable by small-scale farmers. To avoid such limitations, a Thai indigenous crossbred line (C line), selected as a candidate meat-type chicken to survive in the tropical environment, was examined for its capacity to tolerate the tropical climate and for its immune functions. Comparisons, in terms of the stress and innate and humoral immune responses using the heterophil-to-lymphocyte ratio, abdominal exudative cell phagocytic activities, and serum anti-SRBC titer, were made between C-line chicks and the corresponding cohorts from their low-meat-yielding Thai indigenous (T line) parents and from high-meat-yielding commercial broiler (B line) chickens. The responses were evaluated in the 3 different seasons of Thailand (monsoon, summer, and winter). Significantly higher stress levels (P < 0.001), based on the heterophil-to-lymphocyte ratios, were detected in the B line chicks compared with those in the T and C lines at all ages regardless of the season, suggesting that the B line chicks were vulnerable to tropical heat stress whereas the T and C lines were well adapted, with no significant differences detected between the latter two. The innate and humoral immunities of B-line chicks were significantly lower (P < 0.001) than those of T-and C-line chicks. The differences were immense in the summer, when the immunity of the C-and T-line chicks outperformed that of the B-line chicks, with mean opsonized-SRBC phagocytic activities of 7.90, 8.31, and 4.74 and mean IgG titers of 8.00, 8.40, and 5.10, respectively. This could be a consequence of the heat stress causing immunosuppression in B-line chicks, and could represent a noteworthy adaptation to the tropical conditions of the C-and T-line chicks. The apparent climate-tolerant capacity conserved in the C-line chickens, with approximately 50% T genetics, could serve as a guideline for further genetic improvement toward a high-meat-yielding chicken that retains a suitable heat tolerance.

Pathogen contamination in fishmeal (FM) and the imbalanced amino acid profile in soya meal (SYM) are the disadvantages of the common protein sources in broiler diets. Therefore, FM, SYM and three species of cricket powder (Acheta domesticus: AD, Gryllus testaceus: GT and Gryllus bimaculatus: GB) were screened based on the in vitro digestibility of dry matter (DMd), organic matter (OMd) and crude protein (CPd) to assess whether these insects could be a sustainable alternative protein source for broiler nutrition. Stomach mucosa, duodenal mucosa and pancreas were extracted from broilers to obtain crude enzyme extract (CTX) using two stages of in vitro digestibility. The first stage was performed using gastric mucosa CTX, whereas CTX from the duodenal mucosa and pancreas were added for the second stage. SYM and GB had similar DMd, which were lower than FM, AD and GT (P<0.01). The highest OMd was observed in FM, followed by AD, GT, GB and SYM (P<0.01). A higher CPd was found in the crude protein calibration group (CPd-Cal), in which substrates were adjusted to obtain an equivalent crude protein level as the non-calibration group (CPd-Non). Interestingly, a strong correlation (r=0.99, P<0.01) was found between CPd-Cal and CPd-Non, with the highest CPd presented in FM, followed by SYM, AD, GB and GT (P<0.01). A significant negative correlation was found between the CPd from both groups (CPd-Cal and CPd-Non) and crude fibre (r=-0.96 and -0.95, P<0.05, respectively), whereas a positive correlation was observed for ash (r=0.91 and 0.93, P<0.05, respectively). AD has great potential as a protein source for broilers, greater than other cricket species, based on its DMd, OMd and CPd. However, the CPd of all insect species was lower than that of FM and SYM. Therefore, pre-treatment protocols should be performed to improve nutrient utilisation.