ABSTRACT
Background and Aim: The meat supply of local poultry for human consumption is greater than that of fast-growing poultry in Niger. However, meeting the protein needs of these local chickens is a major challenge due to the availability of protein sources and their cost. Nowadays, insect larvae such as houseflies are used and even recommended as animal feed; hence, the need to evaluate the effect of housefly (Musca domestica) larvae on the growth performance of local chickens. This study investigated the feeding effects of housefly larvae on the growth performance and carcass characteristics of local Nigerien chickens and determined the rate of fish meal substitution, in fresh or dry larvae form, whichever would be preferable. Materials and Methods: A total of 165 3-week-old local unsexed chickens of the salmon variety, weighing 120.3 ± 15.43 g, were used to evaluate the effect of housefly (M. domestica) larvae on their growth performance and carcass yield (CY). The experiment consisted of five treatments with three replicates, that is, 15 batches of 11 animals each. Five iso-protein-caloric diets were developed with 25%, and then 50% fish meal substitution with fresh and dried housefly larvae. The chicks were reared together during the first 3 weeks for their adaptation, during which they were fed an imported starter commercial feed, ad libitum. After that, they were weighed weekly for 12 weeks. Next, the body weights (BWs) were taken weekly for all chicks, feed daily intake and mortality were recorded daily, and average daily gain, feed conversion ratio (FCR), and viability rate were calculated. In the end, four chickens (two males and two females) per batch were slaughtered for the CY evaluation, breast meat, drumstick and tight (legs), and wings. Statistical analyses were performed using a linear mixed model for repeated data. Results: The weight, FCR, and carcass traits were unaffected by either the rate or larvae state. Conversely, the growth rate was improved, and feed consumption was increased. Notably, the chickens consumed more feed but grew faster with fresh larvae and at a higher substitution rate. Conclusion: This study reported that 50% fresh or dried housefly larvae substituted into the fish meal in growing local chicken's diets had no effect on their BW, FCR, and carcass traits but increased the growth rate and feed consumption.
ABSTRACT
The objective of this paper is to study the influence of physiological factors that affect the energy balance, such as lactation stage and parity, on milk yield and composition, milk and blood fatty acid concentrations, blood metabolites and hormones in healthy early lactation cows. Thirty-two Holstein dairy cows from five Belgian commercial farms were followed. The grass silage-based diets fed to cows fell within normal composition ranges typically offered to dairy cows on commercial dairy farms in the region. Milk and blood were sampled at each official milk recording and used for the determination of milk fat and protein, milk and blood fatty acids, blood metabolites and hormones concentrations. The considered period was 7 to 150 days in milk. As lactation progressed, concentrations of milk 18:0 and 18:1c9, as well as blood non-esterified fatty acids and ß-hydroxybutyrate, decreased, and those of milk C4-C14, blood cholesterol, triglycerides, insulin and IGF-I increased, agreeing with the extensive mobilization of body reserves in early lactation. Lower concentrations of milk C4-C14 and 16:0 and concomitant higher concentrations of milk 18:0 and 18:1c9 suggest a larger body reserve mobilization in first parity cows compared with greater than or equal to second parity cows. This study confirms that early lactation stage along with parity significantly influence milk fatty acids, such as 18:1, and blood metabolites and hormones, such as NEFA and insulin.
