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Genistein, a biologically active isoflavone, exists in many soy products. It is well known that genistein binds to both oestrogen receptor alpha (ERα) and oestrogen receptor beta (ERβ), but it has a higher affinity to ERβ. Genistein can also bind to the G protein-coupled receptor 30 (GPR30, also known as G protein-coupled oestrogen receptor 1 or GPER). Furthermore, weak oestrogenic activity has been found in genistein, but the mechanism of action remains unknown. The aim of this study was to investigate the in vitro effects of genistein on the secretion of progesterone (P4) and oestradiol (E2) in chicken granulosa cells harvested from follicles, as well as the mRNA expression of ERs in these cells. In addition, we examined the expression of key enzymes including steroidogenic acute regulatory protein (StAR), cytochrome P450 side-chain cleavage (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD) in the process of P4 synthesis. The results showed that genistein did not affect the viability of granulosa cells, nor was the proliferating cell nuclear antigen (PCNA) protein changed. Among the 1-, 10-, 100-, and 1,000-nM concentrations tested, treatment with 1 nM genistein for 48 h significantly increased P4 but did not affect E2 secretion. Real-time PCR results showed that the ERβ gene expression in granulosa cells was markedly upregulated by 1 nM genistein treatment for 48 h, but there was no significant difference in ERα and GPR30 expression. Genistein also increased the gene expression of StAR, P450scc and 3β-HSD in the cultured granulosa cells. These results indicate that genistein acts directly on chicken granulosa cells to increase P4 production by upregulating the gene expression of key enzymes through binding in ERβ. It may exert positive effects on the reproduction of late-laying hens and act as an effective and safe feed additive for animals., (© 2018 Poultry Science Association Inc.)

An experiment was conducted to evaluate the effect of outdoor access days on growth performance, carcass yield, meat quality, and lymphoid organ index of a local chicken breed. In total, 864 twenty one-day-old male Suqin yellow chickens, with similar body weight (536±36g), were selected and raised in indoor floor pens that measured 1.42×1.42 m (2 m2, 18 birds/m2) in conventional poultry research houses (36 birds per pen). Two hundred and sixteen birds were allowed outdoor access treatments at 21, 28, 35, and 42 d of age, respectively (access to outdoor for 35, 28, 21, and 14 days, respectively). Each treatment was represented by 6 replicates (pens) containing 36 birds (216 birds per treatment). In the outdoor access treatment, the birds had an outdoor free-range paddock that measured 3×8 m (24 m2, 1.5 birds/m2). The body weight of birds at 56 d of age increased linearly with increasing outdoor access days (P<0.001), but there was no effect of the outdoor access days on the body weight at 42 d of age (P=0.161). The daily weight gain, daily feed intake, and feed per gain from 21 to 42 d of age were unaffected by outdoor access days (P=0.401, P=0.463, P=0.223, respectively). However, the daily weight gain and daily feed intake from 42 to 56 and from 21 to 56 d of age increased linearly with increasing outdoor access days (P=0.002, P<0.001; P=0.001, P=0.004; respectively), while the feed per gain tended to decrease linearly from 21 to 56 d of age (P=0.060). The mortality from 21 to 56 d of age was unaffected by outdoor access days (P=0.261). At 56 d of age, the breast yield increased linearly with increasing outdoor access days (P<0.001), while the foot yield decreased linearly (P=0.016). The light (L*) and red (b*) values of leg meat color increased linearly with increasing outdoor access days (P=0.032, P=0.013, respectively). The spleen: the body weight ratio showed a decreasing and then increasing quadratic response to increasing outdoor access days (P=0.047). The litter moisture content at 42 and 56 d of age increased linearly with increasing outdoor access days (P<0.001, P=0.013, respectively). The findings of this study suggest that increasing outdoor access days advantageously affects the body weight, daily weight gain, feed per gain and breast yield as well as the light (L*) and red (b*) values of leg meat color, while decreasing foot yield., (© 2015 Poultry Science Association Inc.)

An experiment was conducted to evaluate the effect of free-range days on growth performance, carcass yield, meat quality, and lymphoid organ index of a local chicken breed. In total, 1,000 one-day-old male Suqin yellow chickens were raised for 21 d. On d 21, 720 birds with similar BW (536 ± 36 g) were selected and randomly assigned to free-range treatment at 21, 28, 35, and 42 d of age (assigned to free-range treatment for 21, 14, 7, and 0 d, respectively). Each treatment was represented by 5 replicates (pens) containing 36 birds (180 birds per treatment). All the birds were raised in indoor floor pens measuring 1.42 × 1.42 m (2 m(2), 18 birds/m(2)) in conventional poultry research houses before free-range treatment. In the free-range treatment, the chickens were raised in indoor floor houses measuring 3 × 5 m (15 m(2), 2.4 birds/m(2)). In addition, they also had an outdoor free-range paddock measuring 3 × 8 m (24 m(2), 1.5 birds/m(2)). The BW of birds after being assigned to free-range treatment for 7 d decreased significantly compared with that in the conventional treatment (P < 0.05). However, there was no effect of the free-range days on the BW at 42 d of age (P > 0.05). The daily weight gain, feed per gain, daily feed intake, and mortality from 21 to 42 d of age were unaffected by free-range days (P > 0.05). At 42 d of age, the breast yield increased linearly with increasing free-range days (P < 0.05), whereas the thigh, leg, thigh bone, and foot yields decreased linearly (P < 0.05). The lung yield showed a significant increasing and then decreasing quadratic response to increasing free-range days (P < 0.05). The water-holding capacity of the thigh muscle decreased linearly with increasing free-range days (P < 0.05), whereas there was no significant difference in the meat color, shear force, and muscle pH (P > 0.05). The absolute thymus weight and thymus:BW ratio showed a significant increasing and then decreasing quadratic response to increasing free-range days (P < 0.05). The findings of this study suggest that increasing free-range days advantageously affects breast yield, but decreases thigh, leg, thigh bone, and foot yields as well as the water-holding capacity of thigh. No evidence was found that increasing free-range days caused changes in growth performance, meat quality, and lymphoid organs except for changes in water-holding capacity and thymus., (© Poultry Science Association Inc.)

Phytosterols are intended for use as a novel food ingredient with plasma cholesterol-lowering activity. Although phytosterols are naturally present in the normal diet, daily consumption is insufficient to ensure plasma cholesterol-lowering levels. Therefore, phytosterols may be added to the diets to achieve the desired cholesterol-lowering activity. A subchronic laying hen safety study was conducted to examine if high-dose phytosterols could affect the safety of hens. Three hundred sixty 21-wk-old Hy-Line Brown laying hens were randomly assigned to 5 groups with 6 replicates of 12 birds each; after 3 wk, birds were fed diets supplemented with 0, 20, 80, 400, and 800 mg/kg of phytosterols for 12 wk. Throughout the study, clinical observations and laying performance were measured. At the end of the study, birds were subjected to a full postmortem examination: blood samples were taken for clinical pathology, selected organs were weighed, and specified tissues were taken for subsequent histological examination. No treatment-related changes that were considered to be of toxicological significance were observed. Therefore, a nominal phytosterol concentration of 800 mg/kg was considered to be the no-observed-adverse-effect level.

An experiment was conducted to evaluate the effect of stocking density on growth performance, carcass yield, and immune status of a local chicken breed. In total, 840 one-day-old male Suqin yellow chickens were placed into 4-m(2) cages in groups of 50 (low), 70 (medium), or 90 (high) birds. Each treatment was represented by 4 replicates (cages). The cages measured 2.84 × 1.42 m; half of the area of the cage (2 m(2)) was used from 1 to 28 d and the whole cage was used from 29 to 42 d. Stocking densities were 25, 35, and 45 birds/m(2) from 1 to 28 d and 12.5, 17.5, and 22.5 birds/m(2) from 29 to 42 d (low, medium, and high, respectively). Final production (live bird mass after fasting) per unit area was 14.46, 19.46, and 24.23 kg/m(2), respectively, at 42 d of age. Several immune parameters were evaluated, and the growth performance, carcass yield, and meat quality were determined. Body weight at 28 and 42 d of age was significantly reduced as the stocking density increased (P < 0.05). A depression in daily weight gain was noticed from 1 to 28 d and 1 to 42 d of age, and daily feed intake decreased significantly in each period as density increased (P < 0.05). The feed/gain from 29 to 42 d and from 1 to 42 d of age decreased as density increased (P < 0.05). At 42 d, there was no effect of the stocking density on carcass, eviscerated carcass, breast, and abdominal fat yields (P > 0.05). The thigh yield of chickens in the medium-density group improved significantly (P < 0.05) compared with those of the other 2 groups. The water-loss rate, shear force, and meat color of the muscle were unaffected (P > 0.05) by the stocking density, but pH values increased slightly as density increased. No significant difference was noted in the immunological parameters, but the blood total protein and potassium were significantly affected by stocking density (P < 0.05). The findings of this study suggest that increasing the stocking density advantageously affected feed/gain and decreased the final BW, whereas no evidence was found that stocking density caused changes in any of the measured immune parameters.