Effect of laying parity and sex ratio on reproduction performance and biochemical parameters of White Roman geese kept in an environmentally controlled house

1. This study aimed to investigate the effect of the first and third parities and one male: four females (1 M:4F) and 1 M:6F sex ratios of White Roman geese on their reproductive performance and biochemical parameters in an environmentally controlled house.2. Ganders (n = 136) and geese (n = 656) from the first and third parity were randomly placed into eight pens. These eight pens were assigned to one of four treatments in a 2 × 2 factorial arrangement (two sex ratio groups × two parity groups). The first and third parity treatment groups had 1 M:4F (each pen containing 20 ganders and 80 geese) and 1 M:6F (each pen containing 14 ganders and 84 geese) sex ratio treatment groups, respectively, replicated twice.3. Blood samples were collected from the geese at different time points: upon entering the house (ST), the beginning of the lighting regime of 7 L:17D for six weeks (LC6W), lighting adjustment to 9 L:15D for 6 weeks (9C6W), the peak of egg production (PEP) and the end of egg production (EEP).4. The first parity group had a longer laying period than the third parity (274 vs.191 days). First parity had a lower egg production rate than third parity during whole stage (18.7 vs. 25.4%). Fertility in 1 M:4F group was significantly higher than in 1 M:6F rate group (54.7 vs. 45.1%) at all periods.5. Plasma levels of total protein, albumin, globulin, triglycerides, calcium and phosphorus concentrations were significantly higher for whole laying period in first parity geese compared to third parity birds.

Photostimulation decreases fearfulness, but improves growth performance and egg quality of breeder Pekin ducks

Lighting is a critical environmental factor that influences production performance and welfare of poultry, however Pekin ducks can typically be housed under 24 h (24 h) of light. 460 hatchlings were randomly allocated to 4 rooms with two pens in each room. The rooms were allocated to 24 h light or PS. PS was achieved by gradually increasing photoperiod by half an hour per week from days 112 to 238 and held at 18 h light for the rest of life. Prior to the onset of lay, pens were organized with 30 hens and 7 drakes/pen (4 pens/treatment). We measured bodyweight at weeks 0, 1, 2, 5, 10, 19, and 29, feed intake at weeks 1 to 7 and feed conversion ratio (FCR) was calculated for weeks 1, 2, and 5. Eggs laid were recorded daily from weeks 20 to 31. Novel object test (NOT) was done at weeks 1, 5, 10, 19, and 29, transect welfare scoring at week 30, egg quality assessment at weeks 28 and 29, and fertility was determined at weeks 28 and 29. Statistical analyses were done using 2-way ANOVA, T-test, or Friedman Test with a Tukey-Kramer test as post-hoc. A p ≤ 0.05 was considered significant. Drakes bodyweight was higher in the PS compared to 24h treatment at weeks 5 (p < 0.01) and 10 (p < 0.001). No difference was observed in FCR, fertility, or transect data. NOT showed lower fear response (p < 0.05) at weeks 5 and 10 in the PS compared to 24 h treatment. The 24 h treatment increased the percent eggs laid at weeks 23 (p < 0.05), 24 (p < 0.01) and 25 (p < 0.05) compared to the PS. However, there was a higher egg weight (p < 0.001), yolk weight (p < 0.05), Haugh unit (p < 0.05), and shell weight (p = 0.05) in the PS compared to 24 h treatment. Our findings support that PS may help decrease fearfulness, improve growth performance and egg quality of breeder ducks.

The proteome and metabolome changes distinguish the effect of dietary energy levels on the development of ovary in chicken during sexual maturity

To deeply understanding the impact of peripheral energy level on the development of ovaries during the sexual maturation of chicken, in this study, the ovaries and serum of sexually mature and immature chickens at the same age from different energy level groups were collected, and the proteome and metabolome were detected. The results of ovarian and serum metabolomics revealed that dietary energy levels affected the energy metabolism and fatty acid oxidation of ovary in chicken, including the up-regulated expression of dihydroacetone phosphate and α-linolenic acid in high energy level groups. The results of proteomics showed that peripheral energy levels affected the catecholamine biosynthesis and metabolism in ovary before sexual maturation. The integrating analysis revealed that increased energy flux may influence ovarian development by regulating cholesterol reserves and steroid hormone synthesis in the ovaries. In vitro, the cultivation of chicken primary granulosa cells showed that sterol carrier protein 2 played a role in fatty acid synthesis and metabolism but did not significantly affect progesterone synthesis. Overall, dietary energy levels may be involved in the development of the ovaries during sexual maturation by influencing energy metabolism, biosynthesis of unsaturated fatty acids and steroid hormone within the ovaries.

Effect of body weight at photostimulation on productive performance and welfare aspects of commercial layers

OBJECTIVE

Due to current selection practices for increased egg production and peak persistency, the production profile, age at maturity, and body weight criteria for commercial layers are constantly changing. Body weight and age at the time of photostimulation will thus always be the factors that need to be adequately addressed among various production systems. The current study was carried out to determine the effects of pullets' body weight (low, medium, and heavy) on their performance, welfare, physiological response, and hormonal profile.

METHODS

With regard to live weight, 150 16-week-old pullets were divided into three groups using a completely randomized design (CRD) and held until the 50th week. One-way analysis of variance was used to evaluate the data under the CRD, and the least significant difference test was used to distinguish between treatment means.

RESULTS

In comparison to the medium and light birds, the heavy birds had higher body weight at maturity, an earlier age at maturity, and higher egg weight, eggshell weight, eggshell thickness, egg yolk index, breaking strength, egg surface area, egg shape index, egg volume, and hormonal profile except corticosterone. However, the medium and light birds had lower feed consumption rates per dozen eggs and per kilogram of egg mass than the heavy birds. Light birds showed greater body weight gain, egg production, and egg specific gravity than the other categories. At 20 weeks of age, physiological response, welfare aspects, and catalase were non-significant; however, at 50 weeks of age, all these factors-aside from catalase-were extremely significant.

CONCLUSION

The findings of this study indicate that layers can function at lower body weights during photostimulation; hence, dietary regimens that result in lighter pullets may be preferable. Additionally, the welfare of the birds was not compromised by the lighter weight group.

Effect of early photostimulation at 15-weeks of age and everyday spin feeding on broiler breeder performance

To prevent broiler breeders from growing too quickly and becoming too large for optimum reproduction, their dietary intake is restricted. While current restricted feeding programs, such as skip-a-day feeding (SAD), improve the economic efficiency of broiler breeder operations, this management practice impacts bird welfare. There is an interest in finding strategies that could reduce the impact of feed restriction during broiler breeder rearing. This research investigated the effects of feeding pullets on an advanced growth curve for early photostimulation at 15 wk (15P) or standard growth curve for photostimulation at 21 wk (21P), using either an every-day-spin feeding program (EDS) or SAD feeding, on the reproductive parameters of broiler breeder hens in a 2 × 2 factorial arrangement. Overall, advancing the growth curve (15P) decreased blood corticosterone levels compared to 21P, but EDS resulted in higher blood corticosterone levels compared to SAD. At the end of rearing in both 15P and 21P, EDS pullets weighed less than SAD pullets. The onset of egg production was 20 and 24 wk of age for the 15P and 21P hens, respectively. Despite an earlier onset, 15P hens did not produce more eggs than 21P hens through 65 wk of age. Egg weight was reduced for 15P compared to 21P until 30 wk of age. The 15P hens had a greater number of double yolk eggs than the 21P hens. Fertility and hatch were not impacted by the advanced growth curve and early photostimulation. Although the current research indicates the potential to reduce feed restriction associated welfare issues by rearing broiler breeder pullets for an earlier photostimulation onset, further research in needed to determine if this management technique can be improved to optimize hen reproductive efficiency.

Effects of age at photostimulation on sexual maturity and reproductive performance in rooster breeders

The 2 × 4 factorial experiment was designed to determine the effect of strain and photostimulation age on sexual maturity and reproductive performance of rooster breeders. A total of 96 White Leghorn (WL) and 120 Beijing You Chicken (BYC) roosters were randomly allocated to 4 treatments at 14 wk of age. The treatments represent photostimulation at 16, 18, 20, and 22 wk of age, respectively (PS16, PS18, PS20, and PS22), in both strains. Photostimulation was achieved by increasing the day length from 8L:16D to 14L:10D and by increasing lighting intensity from 10 lx to 80 lx. Three birds from each interaction were sacrificed to characterize the comb and testis weights at 4 time points: 1 d before photostimulation and 2, 4, and 6 wk after photostimulation. Semen quality and hatching performance with the semen of the experimental roosters were measured at 30 and 45 wk of age, respectively. Results showed that the testis weight of PS20 and PS22 in WL and BYC was 6.4- and 2.9-fold higher than that of PS18 before photostimulation, while testis weight of PS18 in both strains increased sharply after photostimulation. The diameter of seminiferous tubules increased in the photostimulated roosters as compared with the nonphotostimulated ones, and mature spermatozoa were produced 4 wk after photostimulation and at 20 wk of age for PS16. The WL had lower semen volume and total sperm count than BYC (P < 0.01), but there was no difference on effective sperm count (P > 0.05). In addition, semen quality traits were not affected by age at photostimulation (P > 0.05) in both strains. The fertility and hatching performance were not affected by strain or photostimulation age (P > 0.05). In summary, the sexual maturation of rooster breeders can be advanced by photostimulation at an early age, which does not lead to a difference in semen quality or hatching performance at adult stage.

Avian Physiology: Are Birds Simply Feathered Mammals?

There are marked differences between the physiology of birds and mammals. These reflect the evolutionary distance between the two classes with the last common ancestor estimated as existing 318 million years ago. There are analogous organ systems in birds and mammals. However, marked differences exist. For instance, in the avian gastro-intestinal tract, there is a crop at the lower end of the esophagus. This functions both to store feed and for microbial action. The avian immune system lacks lymph nodes and has a distinct organ producing B-lymphocytes, namely the bursa Fabricius. The important of spleen has been largely dismissed until recently. However, its importance in both innate and specific immunity is increasingly recognized. There is a major difference between birds and mammals is the female reproductive system as birds produce large yolk filled eggs. The precursors of the yolk are synthesized by the liver. Another difference is that there is a single ovary and oviduct in birds.

Effect of age at photostimulation on sexual maturation and egg-laying performance of layer breeders

The objective of this study was to determine the effect of age at photostimulation on sexual maturity and performance of layer breeders. A total of 192 fourteen-wk-old White Leghorn (WL) breeder hens were randomly allocated to 4 treatments of 48 birds each, with 2 replicates per treatment. The birds were photostimulated at 16 (PS16), 18 (PS18), 20 (PS20), and 22 (PS22) wk of age. Four birds per treatment were randomly selected to evaluate sexual organ development at 1 D before photostimulation and 2, 4, and 6 wk after photostimulation. The ovary weight, large yellow follicles number (LYF), oviduct weight, and oviduct length of PS18 increased sharply after photostimulation. Conversely, the increase in PS16 was not observed until 2 wk after photostimulation. There was no difference in age at sexual maturity between treatments (P > 0.05). The PS16 had the longest interval (28 D) from photostimulation to 5% egg production, while PS22 reached 5% egg production 7 D before photostimulation. The PS22 had lower peak production (P = 0.02) and less egg production (P = 0.02) than other treatments. The PS16 had more broken and abnormal eggs (P = 0.01) and lower hatchability (P = 0.04) than other treatments. In conclusion, photostimulation at 16 and 22 wk of age decreases hatchability and egg production, respectively, and photostimulation at 18 wk is appreciated for the WL breeder hens.

Effect of age at photostimulation on reproductive performance of Beijing-You Chicken breeders

This work studied the effect of age at photostimulation on reproductive performance of Beijing-You Chicken (BYC) breeders. A total of 384 fourteen-week-old BYC breeder hens were randomly allocated to 4 treatments of 96 birds each, with 2 replicates per treatment. The treatments represent photostimulation at 16, 18, 20, and 22 wk of age, respectively (PS16, PS18, PS20, and PS22) by incrementally increasing day length from 8L:16D to 14L:10D and by increasing lighting intensity from 10 to 80 lx. Egg production was recorded for each replicate until 51 wk. Four birds randomly selected from each treatment were sacrificed to characterize sexual organ development at 4 time points: 1 D before photostimulation and 2, 4, and 6 wk after photostimulation. Eggshell quality at peak laying was measured. The results showed that the changes in ovary and oviduct weight in PS22 were 8.68- and 4.27-fold higher than in PS16 at 6 wk after photostimulation. PS16 had an earlier age at 5% egg production than PS20 and PS22 (P = 0.003). The interval from photostimulation to age at 5% egg production in PS20 and PS22 was shorter than in other treatments (P = 0.005). Later peak egg production was seen in PS20 (211.0 D) and PS22 (218.0 D) than in PS16 (183.0 D) and PS18 (190.0 D, P = 0.020), but the laying rate of PS20 decreased slowly after peak laying. PS20 and PS22 had higher egg weights than PS16 and PS18 at peak laying (P = 0.018). Age at photostimulation had no effect on egg number, defective egg number, or hatchability (P > 0.05). In summary, the onset of lay can be advanced by photostimulation at early ages, but there is no difference on egg production until 51 wk. Photostimulation at 20 wk improves peak of laying and laying uniformity.

Evaluation of the Impact of Light Source on Reproductive Parameters in Laying Hens Housed in Individual Cages

Higher light wavelengths have been shown to stimulate extra-retinal photoreceptors more efficiently than lower wavelengths to promote reproduction in poultry. We developed a light emitting diode (LED) bulb that emits 60% of its light in the red spectrum (LED-R), and evaluated the effects of different light sources on growth and reproduction in commercial layer hens. Three rooms equipped with either 100W incandescent, 15W compact fluorescent (CFL), or 10W LED-R bulbs were populated with 96 Lohmann LSL-Lite layers housed in individual cages from 14 to 69 weeks of age (woa). Pullets were initially maintained on a 10-h photoperiod, then photostimulated at 18 woa. Surprisingly, regardless of the light source, plasma levels of estradiol peaked at 16 woa, 2 weeks before photostimulation, and egg-laying was initiated at 19 woa. As a direct correlation between age at first egg and body weight was identified, metabolic cues most likely served as a primary trigger to initiate sexual maturation prior to photostimulation. Overall egg production and cumulative egg numbers were similar among treatments. Interestingly, a second increase in estradiol was observed at 52 woa under all treatments, suggesting an additional ovarian stimulation, possibly associated with an additional follicular recruitment at that age. Overall, changes in estradiol concentrations were more pronounced in hens maintained under LED-R light than in hens exposed to incandescent and CFL, especially for the second increase, suggesting that a higher amount of red light leads to stronger ovarian activity. Maintaining hens under LED-R bulbs also resulted in lower feed consumption, which combined with the lower energy consumption of LED-bulbs (LED-R: 306 kW; incandescent: 2,514 kW; CFL: 422 kW) could reduce the production cost.

Early photostimulation at the recommended body weight reduced broiler breeder performance

To synchronize the onset of sexual maturity in the face of high BW variation, the age at photostimulation has been increasing in the broiler breeder industry. This experiment studied the effects of increased BW and earlier photostimulation on broiler breeder reproductive performance where within-treatment BW uniformity was very high. The experiment tested BW and age at photostimulation treatments in a 2 × 2 factorial arrangement. Hens (n = 120) were fed with a precision feeding system to allocate feed individually following the breeder-recommended target BW (Standard) or to a 22% heavier target BW curve reaching the Standard 21 wk BW at 18 wk (High). Hens were photostimulated at either 18 wk (18WK) or 21 wk (21WK) with a 16L:8D photoschedule. Age at first egg (AFE) and individual egg production to 55 wk were recorded. Differences were reported as significant if P ≤ 0.05. The AFE was decreased and maturation interval between photostimulation and AFE was shorter for hens on the High BW treatment compared to the Standard BW treatment (178.1 vs. 194.7 d and 41.8 vs. 58.2 d, respectively). Hens on the 21WK treatment had a decreased AFE compared to the 18WK treatment (177.0 d vs. 195.9 d) and their maturation interval was shorter (30.0 d vs. 69.9 d). The CV for AFE was higher in the 18WK treatment compared to the 21WK treatment (28.2% vs. 11.2%). Total egg production was higher for hens on the High BW treatment compared to the Standard BW treatment (129.4 vs. 92.8, respectively). Total egg production was higher for hens on the 21WK treatment compared to the 18WK treatment (138.4 vs. 83.8, respectively). Egg weight of Standard BW × 18WK hens was lower compared to High BW × 18WK hens. Current recommended breeder BW may be too low for optimal sexual maturation after photostimulation. It is concluded that even when BW variation is minimized, photostimulation at 18 wk of age is not recommended.

Developmental phenotypic plasticity helps bridge stochastic weather events associated with climate change

The slow, inexorable rise in annual average global temperatures and acidification of the oceans are often advanced as consequences of global change. However, many environmental changes, especially those involving weather (as opposed to climate), are often stochastic, variable and extreme, particularly in temperate terrestrial or freshwater habitats. Moreover, few studies of animal and plant phenotypic plasticity employ realistic (i.e. short-term, stochastic) environmental change in their protocols. Here, I posit that the frequently abrupt environmental changes (days, weeks, months) accompanying much longer-term general climate change (e.g. global warming over decades or centuries) require consideration of the true nature of environmental change (as opposed to statistical means) coupled with an expansion of focus to consider developmental phenotypic plasticity. Such plasticity can be in multiple forms - obligatory/facultative, beneficial/deleterious - depending upon the degree and rate of environmental variability at specific points in organismal development. Essentially, adult phenotypic plasticity, as important as it is, will be irrelevant if developing offspring lack sufficient plasticity to create modified phenotypes necessary for survival.

An updated model to describe the neuroendocrine control of reproduction in chickens

Since its first identification in quail 15 years ago, gonadotropin inhibitory hormone (GnIH) has become a central regulator of reproduction in avian species. In this review, we have revisited our original model published in 2009 to incorporate recent experimental evidence suggesting that GnIH acts as a molecular switch during the integration of multiple external and internal cues that allow sexual maturation to proceed in chickens. Furthermore, we discuss the regulation of a dual inhibitory/stimulatory control of the hypothalamo-pituitary-gonadal axis involving the interaction between GnIH and gonadotropin releasing hormone (GnRH). Finally, beyond seasonality, we also propose that GnIH along with this dual control may be responsible for the circadian control of ovulation in chickens, allowing eggs to be laid in a synchronized manner.