Enhancing the feed value of cassava tuber meal using different treatment methods for Jumbo quail hens.

Abstract

Globally, the human population is expected to grow by 2 billion over the next 30 years. To cater for this population growth, the current supply of poultry products as major protein sources must be diversified and increased. Diversification would imply the expansion of quail (Coturnix sp.) farming in mainstream poultry production. However, the continuous use of expensive energy sources such as maize (Zea mays) in conventional poultry diets poses socioeconomic and environmental sustainability challenges. This necessitates the identification and exploration of alternative feed sources. Cassava (Manihot esculenta) is a non-conventional energy source that has potential to completely replace maize in poultry diets. However, its efficient utilisation may be restricted by the presence of secondary metabolites such as hydrogen cyanides (HCN). This study was, therefore, designed to examine the effect of different heat treatment methods (autoclaving, boiling, and oven-drying) of cassava tuber meal(CTM) as a complete replacement of maize on productive performance, egg quality and shelflife parameters, haemato-biochemistry, welfare indicators, visceral morphometry, carcass characteristics and breast meat quality of Jumbo quail hens. A total of 240, five-week-old Jumbo quail hens (191g ± 16.60 live-weights) were randomly allocated into 60 cages (4 hens/cage) based on body weight to produce 12 replicates per dietary treatment. The diets were formulated to be isonitrogenous and isocaloric as follows: a conventional maize-based layer diet without CTM (CON), and CON in which 100% maize was replaced with raw (CTMR), boiled (CTMB), autoclaved (CTMA), and oven-dried CTM (CTMO). The experiment lasted from 6 - 14 weeks of age during which layer performance traits (e.g., feed intake (FI), feed conversion ratio (FCR), rate of lay (ROL), egg weight (EWT), and internal and external egg quality attributes) were determined. At 12 weeks of age, a total of 180 eggs (3 eggs/ cage) were used to determine shelf-life indicators (e.g., egg weight, albumen height, pH and Haugh unit (HU)) at days 1, 5, and 10 of storage under room temperature (20 - 25°C). At 14 weeks of age, all quail were slaughtered at local abattoir, while bleeding, about 4 mL of blood was randomly drawn from two randomly selected birds and immediately placed in sterilized test tubes for haemato-biochemical analysis. Thereafter, the carcasses were eviscerated and used to measure carcass characteristics, internal organ sizes and breast meat quality. All measured parameters were subjected to procedure of general linear models (PROC GLM) in SAS, while the welfare data was subjected to Kruskal-Wallis test. The raw or thermally-treated CTM samples showed variations on essential amino acids (AA; i.e., methionine, lysine, threonine, etc.), however, oven-dried CTM tended to have negative effects on AAs. Diet CON promoted higher (P <0.05) overall FI than diet CTMB. Furthermore, birds on diet CTMB had lower (P <0.05) overall BWG than birds on the CON diet. However, the CON group had the highest (P <0.05) final body weight (FBW), followed by those on diet CTMR and the lowest (P <0.05) FBW was from those on diet CTMB. There were no (P >0.05) dietary influences on overall FCR and mortality. Fourteen-week-old birds fed the CON diet had higher (P <0.05) ROL than diet CTMR. In weeks 10, 12 and 14, eggs from CON group had higher (P <0.05) egg colour values compared to CTMB, which promoted lower egg colour values. Furthermore, birds reared on diet CON had the least (P <0.05) shape index than those on diet CTMO. Fourteen-week-old birds fed diets CTMB and CTMO had smaller (P <0.05) egg diameter compared to those fed with diet CON. Moreover, diet CTMA resulted in heavier (P <0.05) shell weight than diet CTMR. Diet CON resulted in the lowest (P <0.05) yolk index whereas diets CTMA and CTMR resulted in the highest. At day 5 of shelf-life, eggs from the CON group had the highest (P <0.05) egg breaking strength while the lowest strength was from the CTMR group. At day 10, eggs from the CTMA group had the lowest (P <0.05) albumen pH, whereas the highest albumen pH was from the CON group. Quail hens fed with CON diet had heavier (P <0.05) carcass weights than those fed with diets CTMR and CTMB. Diets CTMO and CTMB resulted in heavier (P <0.05) wing weights than diets CON and CTMA. Diet CON caused lower (P<0.05) meat pH after 24 hours of slaughter than diet CTMB. The Kruskal-Wallis H test showed that there was a significant treatment effect on the latency-to-lie test [X2(2) = 10.18; P =0.0375]and not on gait and feather scores. Although the maize-based diet showed the best performance, the autoclaved and oven-dried cassava treatments performed better than the boiled cassava treatment in terms of productive performance, egg quality parameters, and indices of carcass quality. This study showed that boiling of CTM has no benefit for layer quail productiontherefore, it should not be considered when you want to maximize the production.