M. Skřivan

A mobile system for rearing meat chickens on pasture

The effect of grazing on the productive performance and meat quality was evaluated for chickens (Ross 308, n = 192). Chickens were kept in two pens on wooden shavings (2 × 96) from one day of age. On day 23 in the original pen until the end of the experiment at 6 weeks of age. Both groups were fed the same pelleted feed ad libitum. For the pasture-reared group, the moveable shelter was moved twice daily around the pasture with a predominance of grass species. The herbage intake of chickens was indirectly assessed by compressed sward height measurement after each cage movement, which employed a rising plate-meter. In the pasture, chickens preferred grass over clover. There was no significant effect of grazing observed on chicken body weight. The mortality of chick - ens in the grazing group was lower than that in the control group. Pasture treatment improved meat flavour by 9% (P = 0.014), produced breast meat with significantly higher ( P = 0.009) redness, and almost doubled the concentra - tion of α-tocopherol ( P < 0.001). There were no significant effects of grazing on the dry matter, fat, cholesterol or pH of the meat. The production of TBARS in the breast meat of the pasture group after storage at 4°C for 5 days was lower ( P = 0.013) than that in the breast meat of the control chickens. Although the differences between K, Ca, P, Mg, and N concentrations in pasture and soil before and after grazing reached 20%, these differences were not significant.

Effect of green alga Planktochlorella nurekis on selected bacteria revealed antibacterial activity in vitro.

The green alga Planktochlorella nurekis (Chlorellaceae, Chlorophyta) is considered a producer of antibacterial mixture of long-chain fatty acids, which has possibly similar composition and mode of action as chlorellin produced by another green alga, Chlorella vulgaris. Although the antibacterial properties of C. vulgaris have been reported, the interactions of P. nurekis with bacteria have not been determined yet. The aim of this study was to elucidate the effect of P. nurekis water suspension on growth of selected gastrointestinal bacteria in vitro so that it could be used as a suitable feed supplement in animal farming. Unknown bacterial populations occurring in the algal suspension were identified using 16S rRNA sequencing assay. Selected strains were cultivated with lyophilized P. nurekis and the antibacterial effect was monitored. The composition of fatty acids and heat sensitivity of antibacterial substances were also examined. Sequencing analysis of 71 bacterial 16S rRNA genes in xenic algal suspension identified common environmental microbiota, one strain belonging to the class Alphaproteobacteria, 17 to Betaproteobacteria, 44 to Gammaproteobacteria (dominated by Pseudomonas putida strains), and nine to Sphingobacteria. The antimicrobial activity of P. nurekis suspension was tested at a concentration range of 0.75–6 mg/ml. The highest inhibitory effect was observed on bifidobacteria. Statistically significant reductions in bacterial counts were also observed for Escherichia coli, Salmonella enterica var. Enteritidis, S. enterica var. Infantis, Campylobacter jejuni, and Arcobacter butzleri. The growth of Lactobacillus johnsonii was significantly stimulated. The relative proportions of C14–C22 fatty acids in P. nurekis were found as follows: saturated 54.28%, monounsaturated 30.40%, and polyunsaturated 7.16%. The antibacterial compounds present in P. nurekis suspension exhibited thermostability. The results indicate that P. nurekis can inhibit some pathogenic gastrointestinal bacteria and seems to be a promising essential nutrients source in animal nutrition.

Effect of dietary fat type on intestinal digestibility of fatty acids, fatty acid profiles of breast meat and abdominal fat, and mRNA expression of lipid-related genes in broiler chickens

A group of 240-day-old Ross cockerels were used in a 4-week experiment to assess the effect of the fat type on the intestinal digestibility of fatty acids (FAs), the FA profiles of breast meat and abdominal fat, and the mRNA expression of six hepatic lipid-related genes. Experimental diets were supplemented with rapeseed oil, pork lard or palm oil at 60 g/kg. In the control diet, wheat starch was substituted for the fat source. The highest ileal digestibility of the fat and all FAs (except stearic acid) was observed in chickens fed lard. The content of fat in the breast meat of chickens was not significantly influenced by the fat supplements. The FA profiles of breast meat and abdominal fat reflected the FA composition of the diet. In the meat of chickens fed rapeseed oil, oleic acid was the predominant FA. Palmitic acid was the most abundant FA in the meat of chickens fed lard or palm oil. Oleic acid was the most abundant FA in the abdominal fat of all chickens. The highest mRNA expression of desaturases (Δ5-, Δ6- and Δ9-) was observed in chickens fed palm oil. The mRNA expression of hepatic FA synthase was higher in chickens fed palm oil or lard than in chickens fed rapeseed oil. The expression of HMG-CoA reductase was higher in chickens fed palm oil than in those fed rapeseed oil or lard. It can be concluded that rapeseed oil and lard are better sources of lipids than palm oil. These former two sources contain more digestible fatty acids and provide a lower concentration of SFAs in the meat and fat of chickens.

Limestone particle size and Aspergillus niger phytase in the diet of older hens

Abstract The aim of this experiment was to evaluate the influence of limestone particle size and phytase (F) on performance, physical egg parameters, mineral digestibility and microbial colonisation in the digestive tract in older hens aged 60–71 weeks. One hundred and sixty Lohmann Brown hens were housed in enriched cages. The 2 × 2 factorial experiment included two levels of 3-phytase NATUPHOS® (0 and 350 FTU/kg), two sizes of limestone grain (coarse limestone (CL) and a mix of CL and fine limestone (FL) (1:1)) in mixed feed. All of the diets contained 4.4 g/kg of total phosphorus and 34 g/kg of calcium. Coarse limestone with F addition significantly increased hen-day egg production (p = .018). The phytase supplement at 350 FTU/kg significantly increased shell quality characteristics. Haugh units (p = .039) and albumen index (p = .008) was higher when using the limestone mix, the same applies to yolk index (p = .013). The phytase addition to the mixed feed non-significantly increased calcium and phosphorus digestibility in the ileum by 3.1 and 3.9%, respectively. Intestinal microbiota from each sample did not cluster according to the treatment; however, bacteria belonging to the genera Turicibacter and Lactobacillus occurred with higher frequency in the ileum of hens that were fed mixed feed enriched with phytase. In conclusion, limestone particle size (1 to 2 mm) with F addition at 350 FTU/kg in a wheat-maize-soybean meal-based diet increased egg production while maintaining egg content and eggshell quality in older hens. Ileal microbiota was influenced by F supplementation in the diet.