Antonija Holcman

Effects of two probiotic additives containing Bacillus spores on carcass characteristics, blood lipids and cecal volatile fatty acids in meat type chickens.

The objective of this study was to evaluate effects of two commercially available probiotic additives, containing Bacillus spores, on carcass and meat characteristics, serum lipids and concentration of cecal volatile fatty acids of meat type chickens. Birds were fed regular corn-soy meal based feed (control), supplemented with additive A, containing 1.6 × 10(6) spores per gram of feed of Bacillus subtilis and Bacillus licheniformis (group A) or additive B, containing the same concentration of Bacillus cereus var. toyoi spores (group B). One hundred and twenty birds (20 per replicate) were slaughtered at the age of 55 days. Results showed that birds in group B had higher (p < 0.05) final body weight compared to birds from group A and higher carcass weights and yield percentages compared with control. Breasts and whole legs were also heavier in group B, compared to control, but not the yield. Group A had higher yield of wings and lower abdominal fat weight compared to group B (p< 0.05), but not compared with control. Total cholesterol was not affected by the dietary treatment, on contrary both probiotics elevated the LDL (p < 0.05) and lowered HDL cholesterol, thus unfavourably changed animals blood serum cholesterol profile. Both probiotics influenced the cecal fermentation, which was observed as decrease in cecal concentrations of propionic, butyric, n-butyric and n-valeric acids, but the differences compared to control group were statistically significant for group A only. It was established that probiotic additive B was more effective regarding carcass and meat part weights than additive A, however the animals from group B also had more abdominal fat and their meat had significantly higher conductivity than control group, which is not considered as beneficial.

Effects of divergent selection for 8-week body weight on postnatal enzyme activity pattern of 3 fiber types in fast muscles of male broilers (Gallus gallus domesticus)

A divergent selection experiment was conducted for 8-wk BW in chickens. At 3, 6, 9, and 12 wk of age, samples of pectoralis profundus (PP) and biceps femoris (BF) muscles from fast-growing and slow-growing lines were used to estimate the enzyme activities and muscle fiber diameter. Microphotometric measurements made in situ of succinate dehydrogenase (SDH, EC 1.3.99.1) and glycerol-3-phosphate dehydrogenase (GPDH, EC 1.1.99.5) were completed on serial sections of PP and BF muscles from male chickens, in order to examine the ratio of SDH:GPDH activity in single fibers. On the basis of the SDH:GPDH activity ratios, muscle fibers were divided using cluster analysis into 3 populations of different fiber types (O = oxidative, OG = oxidative-glycolytic, and G = glycolytic). Cockerels of the SGL attained an 8.1-fold increase and those of the FGL a 6.8-fold increase in BW at 12 wk compared with that at 3 wk of age. The O, OG, and G type fibers of the BF muscles of the SGL had significantly (P ≤ 0.001) lower SDH:GPDH activity ratios than those of the FGL. A step decrease in the SDH:GPDH activity of O, OG, and G fibers in the PP of both lines occurred, and this differed significantly between SGL and FGL (P ≤ 0.001). Age and line effects influenced the diameter of the 3 fiber types in the BF muscle only. In contrast to this response, all 3 fiber types of the PP muscles reached similar diameters in both lines during the growth process from wk 3 to 12. From the results of this study, we concluded that the activities of metabolic enzymes in skeletal muscle fibers are under the influence of muscle type, age, and selection pressure. Microphotometry is a suitable method for the evaluation of enzyme activity measured in a single muscle fiber. The method enables precise estimation of enzyme activities, especially in muscles composed of populations of different metabolic fiber types.

Choice of nest types by hens of three lines of broiler breeders

1. Choice of three different nest types by hens of broiler breeder lines was investigated: metal nests (26 × 29 × 33–45 cm, w × d × h) with inclined rubber mats, metal nests of the same size with litter, and larger wooden nests (30 × 40 × 38) with litter. Three lines were studied: line B (324 females + 36 males), line P (315 + 36), and line WM (306 + 32). Each line was housed in a pen 23·3 × 3·9 m (90·7 m2); half the area was concrete floor with litter, and the other half raised plastic slats, on which stood 84 nests, 28 of each type, in two-tier blocks. 2. Ninety-five per cent of eggs were laid in nests, with significant variation between types: 63% metal littered, 30% wooden littered, and 2·3% metal with inclined rubber mats. Choice between types was similar in the three lines. Hens of line B laid 66% of nest eggs in lower nests, P laid 57% and WM laid 64%. 3. The other 5·1% of eggs were laid on the floor: 1·2% on the litter and 3·9% on the slats in front of the nests. It is suggested that some subordinate hens were excluded from nests, and therefore laid on the floor.

Catalog of genetic variants within mature microRNA seed regions in chicken

MicroRNA (miRNA) is a class of noncoding RNA important in posttranscriptional regulation of target genes. The regulation mechanism requires complementarity between target mRNA and the miRNA region responsible for their recognition and binding, also called the seed region. It has been estimated that each miRNA targets approximately 200 genes and genetic variability of miRNA genes has been associated with phenotypic variation and disease susceptibility in humans, livestock species, and model organisms. Polymorphisms in miRNA genes especially within the seed region could therefore represent biomarkers for phenotypic traits important in livestock animals. Using the updated Version 5.0 of our previously developed bioinformatics tool miRNA SNiPer we assembled polymorphic miRNA genes in chicken. Out of 740 miRNA genes 263 were polymorphic, among them 77 had SNPs located within the mature region, and 29 of them within the miRNA seed region. Because several polymorphisms in databases result from sequencing errors, we performed experimental validation of polymorphisms located within 4 selected miRNA genes in chicken (gga-mir-1614, −1644, −1648, and −1657). We confirmed the presence of nine polymorphisms and identified 3 additional novel polymorphisms within primary miRNA regions in chicken representing 3 layer-type breeds, one layer-type hybrid, and one meat-type intercrossed population. The developed catalog of mir-SNPs in chicken can serve researchers as a starting point for association studies dealing with poultry production traits and designing functional experiments.

Porous concrete block as an environmental enrichment device increases activity of laying hens in cages.

The purpose of this study was to consider the influence of simple and cheap environmental enrichment such as porous concrete on the behavior of laying hens in conventional cages. Forty brown laying hens were housed in individual wire mesh cages: 20 in experimental cages with porous concrete block provided for pecking and 20 in a control group without concrete block provided. Porous concrete block (5 cm length x 5 cm width x 5 cm height) was mounted on the side wall at the height of the hens head. Behavior was studied from 42 to 48 wk of age. A group of 8 hens was filmed for 24 h, and the camera was moved each day so that all 40 hens were recorded over 5 d each wk. Videotaping was performed in wk 1, 3, 5, and 7 of the experiment. States (long-term behavior) were observed with 5-min interval recording (feeding, preening, resting, and remaining inactive), whereas events (short-term activities) were observed with instantaneous recording (drinking, pecking concrete, pecking neighbors, pecking cage, and attempting to escape). Data were analyzed with generalized linear mixed model with binomial distribution for states, and Poisson distribution for events. Monte Carlo Markov Chain methods were used to estimate model parameters. Because posterior distributions of quantities of interest were skewed, medians and standard errors are reported. Hens in experimental cages were more active in long-term behavior than controls (64.9 +/- 1.9 and 59.3 +/- 1.9% of the light period, respectively). Correspondingly, hens in the control group showed more long-term inactivity. In addition to pecking the porous concrete block, hens in experimental cages also showed other short-term activities with greater frequency (4.10 +/- 0.31 and 3.51 +/- 0.25 events per h, respectively). Our hypothesis that hens in enriched cages would have a greater level of activity was confirmed. Provision of a piece of porous concrete block as a pecking substrate enriched the environment of the birds at negligible cost.

External, Internal and Sensory Qualities of Table Eggs as Influenced by Two Different Production Systems

This study was conducted to determine the effects of two production systems (organic vs conventional cages) on egg quality parameters during the late laying period. The effects of a production system were investigated on external and internal quality and on the sensory attributes. The eggs produced in organic system had paler yolks (P<0.001) and thinner egg shells (P<0.05) than the eggs produced in the cages. Overall sensory quality was improved in eggs deriving from hens allocated in cages. Differences between organic and cage eggs indicated lower redness and higher yellowness (P<0.001) in organic eggs than in cage eggs. The organic eggs were characterised by a higher content of a-linolenic and docosapentaenoic acid (P<0.05) and lower content of linoleic acid (P<0.05) than the eggs from cages. The ratio of omega fatty acids, n-6/n-3, was most favourable in the organic eggs (5.93:1). In the cage eggs, the ratio n-6/n-3 was significantly (P<005) higher (955:1).