BackgroundTwo trials were performed to evaluate a partially defatted Hermetia illucens (HI) larvae meal as potential feed ingredient in rainbow trout (Oncorhynchus mykiss Walbaum) diets. In the first trial, 360 trout (178.9 ± 9.8 g of mean initial body weight) were randomly divided into three experimental groups (4 tanks/treatment, 30 fish/tank). The fish were fed for 78 days with isonitrogenous, isolipidic and isoenergetic diets containing increasing levels of HI, on as fed basis: 0% (HI0, control diet), 25% (HI25) and 50% (HI50) of fish meal substitution, corresponding to dietary inclusion levels of 0, 20% and 40%. In the second trial, 36 trout (4 tanks/treatment, 3 fish/tank) were used to evaluate the in vivo apparent digestibility coefficients (ADC) of the same diets used in the first trial.ResultsSurvival, growth performance, condition factor, somatic indexes, and dorsal fillet physical quality parameters were not affected by diet. The highest dietary inclusion of HI larvae meal increased dry matter and ether extract contents of trout dorsal fillet. The use of HI larvae meal induced a decrease of valuable polyunsaturated fatty acids (PUFA) even if differences were only reported at the highest level of HI inclusion. The insect meal worsened the lipids health indexes of the same muscle. Dietary inclusion of insect meal did not alter the villus height of the fish. No differences were found among treatments in relation to ADC of ether extract and gross energy, while ADC of dry matter and crude protein were higher in HI25 if compared to HI50.ConclusionsThe obtained results showed that a partially defatted HI larvae meal can be used as feed ingredient in trout diets up to 40% of inclusion level without impacting survival, growth performance, condition factor, somatic indexes, dorsal fillet physical quality parameters, and intestinal morphology of the fish. However, further investigations on specific feeding strategies and diet formulations are needed to limit the observed negative effects of the insect meal on the FA composition of dorsal muscle.

The aim of this study was to determine consumer ability to discern different levels of beef tenderness established by Warner-Bratzler shear (WBs). A panel of 220 people evaluated 60 samples of longissimus thoracis using a 5-point intensity scale (1: very tough; 5: very tender). Samples differed for commercial category, breed of animals and ageing length of meat. Shear force was measured by Instron equipped with a Warner-Bratzler device on 1.27 cm diameter cores. Correlation coefficient of WBs measurements with tenderness sensory ratings was _0.72. WBs value corresponding to class 3 of the sensory tenderness was 47.77 N. From this value, the range of .59 N) was split into five categories to which connect the five classes of sensory tenderness. The results suggest consumers' difficulty in discriminating category 1 (WBs > 62.59 N) from category 2 (WBs: 52.78-62.59 N) and a greater inclination to distinguish category 5 (WBs < 32.96 N). As WBs category boundaries were probably too restrictive for the panel's selective ability, WBs scale was reduced to 3 categories by joining the two extreme categories (i.e. category 2 with 1 and category 4 with 5). In this case, 55.6% of consumers significantly discriminated tough from intermediate and tender meat and 62.3% distinguished tender from intermediate and tough meat (P < 0.01). Hence, WBs values >52.68 N and <42.87 N allow classification of tough and tender beef in a sufficiently reliable way.

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Growth hormone (GH) exerts its effects on growth and metabolism by interacting with a specific receptor (GHR) on the surface of the target cells. Therefore, GHR has been suggested as candidate gene for traits related to meat production in cattle. The aim of the study was to analyse the polymorphism at position 257 in exon 10 of the GHR gene and investigate relationships with 14 in vivo traits and four meat characteristics in Piemontese animals. The biallelic polymorphism already described was detected using a new PCR procedure. The statistical analysis did not show significant gene substitution effects on growth, size and meat conformation traits. As for meat characteristics, a significant gene substitution of GHR(A) over GHR(G) was observed for drip losses at day 3, with the allele GHR(A) associated with higher values. A significant dominance effect was also observed for this trait. Further investigations in other breeds will be useful for better understanding information on the effect of this GHR polymorphism.

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Samples of longissimus thoracis muscle of young bulls belonging to Piemontese (n=10), Limousin (n=11) and Friesian (n=10) breeds were analysed in order to study the chemical composition, fatty acids and cholesterol content of beef purchased at retail. The breeds and their differences in intramuscular fat content strongly influenced the fatty acids profile. The Piemontese animals displayed the lowest intramuscular fat and SFA content, while Friesian animals showed the highest intramuscular fat, SFA and MUFA content. In general, Limousin animals had intermediate characteristics. A higher PUFA proportion on total fatty acids was observed in Piemontese breed, but the PUFA absolute content (mg/100 g meat) did not differ among breeds. All the three breeds displayed a high content of n-6 fatty acids family and, consequently, a very unbalanced n-6/n-3 ratio. No differences were found for cholesterol content.

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