Influence of age and strain on reproductive performance of the broiler breeder female

Chicken meat is an important source of high quality protein in the diet of most people in the world. Consequently, the increasing demand for this meat has made chicken meat production the most important growth sector among other meat species. This has been achieved by a half century of intensive genetic selection for growth traits; however, this was coupled with poor reproductive performance of broiler breeders. Ross 708 represents a broiler breeder strain that has been developed for breast-meat yield, and has been reported to exhibit poor reproductive performance in comparison to Ross 308, a typical broiler breeder strain. Accordingly, the current study investigated key points involved in the reproductive process that might influence variation in reproductive performance. Ovarian follicles number was the first point to investigate, as they are the main material of the egg. Liver fatty acid profiles were also investigated in order to identify lipid metabolism and the efficiency of dietary fat utilisation, as the liver is the main site that supplies different body tissues with fatty acids. Carcass fat content was also examined as its negative relationship with reproduction is well documented. Finally, the content of calcium in the tibia bone was examined to identify whether variation in egg production was associated with differences in the metabolism of this element. Accordingly, broiler breeder females from Ross 308 and 708 strains, reared under the standard production system on two different commercial farms of PD Hook, were collected throughout the reproductive cycle; starting at 25-week-old and in five weeks interval until 55-weeks of age. Findings showed no difference in the number of both the large yellow follicles (P=0.332), and the small yellow follicles (P=0.134); whereas the number of large white follicles was higher in the 708 ovaries (P=0.005). Differences in lipid metabolism were identified with a strong tendency for the 708s towards having lower content of linoleic acid (P=0.056) in addition to significantly lower a-linolenic acid (P=0.005). Of particular importance is the latter fatty acid as it is the precursor to (n-3) fatty acids, some of which were found to be less (P<0.001) in the 708s including docosapentaenoic (DPA) and docosahexaenoic (DHA). The importance of these fatty acids in follicular maturation is well documented in addition to the importance of the linoleic acid; these findings indicate that the 708s were not receiving adequate levels of the essential fatty acids which might have contributed to their poor reproductive performance. The 708s also laid down significantly more fat (P<0.001) in comparison to the 308s which could be another factor that has impaired their reproduction performance. This could indicate different levels of metabolic hormones which, in turn, have been found to act in concert with the reproductive hormones. 708s also exhibited a trend towards lower content of calcium in their tibiae, with an age by strain interaction and thus suggesting a difference in the metabolism of this element at some ages. The current study has addressed changes of the investigated parameters with age, but the effect of genetic selection on reproductive performance was difficult to address. Rather, some physiological differences have been identified; 708s were found to be receiving inadequate amounts of essential fatty acids, calcium content was found to be less at some ages and they exhibited a higher content of carcass fat. All these factors have the potential to contribute to poor reproductive performance, and once they are taken into consideration better assessment for the effect of the continued genetic selection for more growth traits can investigated

Photic involvement in the reproductive physiology of female domestic fowl.

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.No abstract available

Effect of light and feeding management on sexual maturity and productivity of broiler breeder hens

Six experiments were conducted utilizing broiler breeder females in both windowed and windowless houses to assess or determine: 1) the effect on sexual maturity and subsequent egg production produced by light intensity changes during photostimulation; 2) black-out versus natural daylength rearing programs; 3) effect on productivity of broiler breeder pullets caused by rearing and stimulating photoperiods; 4) effect on egg production resulting from light intensity changes and feed allowance during lay; 5) optimum age and body weight at sexual maturity in broiler breeders; and 6) daily ME requirement of the broiler breeder hen. Traits measured included growth rate, average age and body weight at first egg, peak % hen-day production and age at peak production, rate of decline in % hen-day production, average number of eggs per hen, feed consumed through first egg or per dozen eggs, egg quality and mortality rate. The results obtained indicated that light intensity changes during photostimulation or peak egg production did not affect any of the measured traits. However, birds maintained under high light intensity from hatching (HH) produced more eggs and achieved a significantly higher peak % egg production than birds housed under low light intensity. Rearing photoperiod on the other hand, significantly affect the age at sexual maturity and subsequent performance of the birds. Optimum age (172 d) or body weight (3.4 kg) at sexual maturity were determined from either feeding management or combination of light and feeding management. Hens provided with 540 vs. 435 kcal ME/d commenced laying 14 days earlier with a significant improvement in growth and egg production rates. Neither livability nor egg quality was affected by treatment; however, feed efficiency was significantly depressed by the high energy level. The results indicated also that birds responded significantly better to a higher amount of daily feed intake. Daily dietary energy of 425 kcal ME/bird with 0.0565 g/kcal ME protein:energy ratio was found to support performance adequately through 35 weeks of age but not thereafter, as shown by other diets of either similar protein:energy ratio but higher energy level (500 kcal ME) or lower protein:energy ratios (0.048-0.0533 g/kcal ME) but higher energy levels (450-500 kcal ME)

EVALUATING THE EFFECTS OF MATERNAL AND PROGENY DIETARY SUPPLEMENTATION OF SELENIUM YEAST AND VITAMIN E ON THE PERFORMANCE OF BROILER-BREEDER HENS AND PERFORMANCE AND MEAT QUALITY OF PROGENY

The objectives of these experiments were to evaluate the effects of selenium (Se) and vitamin E (Vit.E) supplementation in maternal and progeny diets on the performance of breeder hens and the performance and meat quality characteristics of progeny. Inclusion of Se, as Se yeast, in the diets of developing broiler breeder pullets resulted in greater Se accumulation of Se (P\u3c0.01) in liver, pancreas, and breast tissues than when Se yeast was not provided. Improving the overall Se status of breeder pullets in the early stages may help maintain adequate tissue Se concentrations during egg production. Maternal supplementation of Se yeast and Vit.E increased the liver and breast Se concentration (P\u3c0.05) of newly hatched chicks compared to the chicks originating from hens not receiving dietary Se. At 7d of age, Se yeast supplementation in either the chick or maternal diet increased breast and liver Se concentrations (P\u3c0.01). At 14d of age, breast and liver Se concentrations remained the highest for chicks supplemented with Se yeast (P\u3c0.01), however there was no effect of maternal Se supplementation. Vitamin E supplementation in either the chick or maternal diets did not affect the liver Vit.E concentrations of chicks at 7 or 14d of age. Supplementing broiler diets with Se yeast and Vit.E improved the meat quality characteristics of raw and marinated breast fillets. The Se content of breast meat from broilers fed Se yeast was higher (P\u3c0.01) than those from broilers that were not fed Se yeast. Antioxidant supplementation improved the drip loss (P\u3c0.05) and oxidative stability (P\u3c0.10) of raw breast fillets after 7d of refrigerated storage. Marination appeared to increase the susceptibility for lipid oxidation of the marinated breast fillets. Dietary supplementation of Se yeast and Vit.E reduced lipid oxidation (P\u3c0.01) of marinated breast fillets after prolonged refrigerated storage, thus improving oxidative stability. Overall, dietary supplementation of Se yeast can increase the accumulation of Se in the tissues of broiler breeder hens and their subsequent progeny. Improvements in the avian antioxidant system may have beneficial effects on the performance of broiler breeder hens, broilers, and the meat quality characteristics of broiler breast fillets

Impact of light during laying hen egg incubation on hatch traits, growth and behaviour

While the impact of various components of light have been studied in broilers and egg production hens, little is known about the impact that light wavelength and duration have on embryo development and welfare in the incubation phase. The overall objective of this research was to evaluate the effect of light wavelength and photoperiod during the incubation of fertile egg production hen eggs. In experiment 1, 640 Lohmann LSL (LSL) and 640 Lohmann Brown (LB) eggs were randomly distributed in 8 incubators. Two incubators per treatment were outfitted with red, blue, or white LED lights, and a 12L (Light):12D (Dark) photoperiod was used throughout incubation. The final two incubators remained dark. At hatch, 144 LSL and 144 LB pullets were placed in 3 brooding rooms under a Near Continuous (NC) or 3 rooms under an Intermittent (INT) lighting photoperiod. Post-hatch, pullet behaviour was video recorded on days 0, 2 and 4. The use of differing light wavelengths during incubation did not affect pullet behaviour post-hatch. A genotype effect was observed, as LSL pullets spent a greater percentage of time at the drinker on days 0 (P=0.012) and 2 (P=0.031), and at the feeder on days 2 (P<0.001) and 4 (P=0.005) compared to LB pullets. Brooding photoperiod also affected early behaviour, as pullets brooded under an INT photoperiod spent a greater percentage of time at the feeder on days 0 (P=0.036) and 2 (P=0.022), less percentage of time resting on days 0 (P=0.005), 2 (P<0.001) and 4 (P=0.004), and a higher percentage of time walking on days 2 (P=0.039) and 4 (P=0.041) than pullets under a NC photoperiod. Experiment 2 was conducted with the objective of determining the effects of in-ovo photoperiod on hatch traits, growth and behaviour post-hatch. During incubation, 400 LSL eggs (n=3) were randomly distributed and exposed to one of 4 photoperiod treatments ((6L:18D (6L), 12L:12D (12L), 18L:6D (18L)) or 0L:24D (0L). At the hatch endpoint, males were evaluated for hatch traits (n=20/treatment), response to stress (heterophil to lymphocyte ratio (H/L), n=15 chicks/treatment) and composite asymmetry (sum of the difference between right and left; femur, tibiotarsus and metatarsus, n=20/treatment). Females (n=30/treatment) were evaluated for hatch traits at the hatch endpoint, and post-hatch growth to 21 days of age, early behavioural output, presence or absence of behaviour rhythms, H:L ratio, and composite asymmetry. Incubation time was reduced (P<0.05) with the use of light during incubation, with the greatest reduction occuring under 18L. However, the spread of hatch and hatchability were not affected. Stress tests (H/L ratio and composite asymmetry) of the male chicks were not affected by treatment. Body weight of female chicks at day 0 (P<0.001), 7 (P=0.001), 14 (P=0.017) and 21 (P=0.027) was higher for chicks hatched from 0L incubation, but flock uniformity did not differ. Stress indicators (composite asymmetry and H:L ratio) at day 21 did not differ. On hatch day the percentage of time chicks from 18L spent walking (P=0.029) was higher than chicks from 6L. Standing (P=0.015) was also higher in chicks from 18L compared to chicks from 0L and 12L incubation. Running (P=0.003) on hatch day was higher in chicks from 18L than chicks from 0L, 6L, and 18L incubation. Time spent at the feeder, drinker, preening, performing aggressive and low incidence behaviours at day 0 were not affected by in-ovo photoperiod. Behaviour rhythm was present in chicks post-hatch for the following behaviours: resting (P=0.035) and walking (P<0.001) during the photophase on day 0; walking on day 1 (P=0.023), resting (P=0.001), and foraging (P=0.017) on day 2, regardless of exposure to light during incubation. In conclusion, regardless of light wavelength used during incubation, provision of darkness such as in the INT brood photoperiod used in this study at an early age, increased chick activity compared to those reared under near-constant light. Overall light wavelength does not affect chick behaviour post-hatch, and the greatest impact with the use of lighting on chick behaviour is due to photoperiod length. A photoperiod up to 18L under red light can be used during incubation without negative effects on stress measures and chick’s behaviour, but it might reduce chick weight at hatch

Anais.

Aspectos tecnicos e economicos da utilizacao de sub-produtos de origem animal na alimentacao de frangos de corte; Fundamentacoes para a nutricao diferenciada de linhagens de frangos de corte; Improvement of incubation egg quality by nutrition; Impact of ambient temperature on amino acid exigency and carcass composition in broilers; Relationship between nutrition and the immune system in poultry; Efeito do balanco entre aminoacidos e a relacao energia/proteina sobre o seu metabolismo: desempenho e composicao corporal em frangos de corte; Modelling energy and amino acid requirements in order to optimise the feeding of commercial broilers.bitstream/item/57643/1/documentos-70.pd

Quantitative trait loci mapping of sexual maturity traits applied to chicken breeding

Many phenotypes are controlled by factors which include the genes, the environment, interactions between genes and interaction between the genotypes and the environment. Great strides have been made to understand how these various factors affect traits of agricultural, medical and environmental importance. The chicken is regarded as a model organism whose study would not only assist efforts towards increased agricultural productivity but also provide insight into the genetic determination of traits with potential application in understanding human health and disease. Detection of genomic regions or loci responsible for controlling quantitative traits (QTL) in poultry has focussed mainly on growth and production traits with limited information on reproductive traits. Most of the reported results have used additive-dominance models which are easy to implement because they ignore epistatic gene action despite indications that it may be important for traits with low heritability and high heterosis. The thesis presents results on the detection of loci and genetic mechanisms involved in sexual maturity traits through modelling both additive-dominance gene actions and epistasis. The study was conducted on an F2 broiler x White Leghorn layer cross for QTL detection for age, weight, abdominal fat, ovary weight, oviduct weight, comb weight, number of ovarian yellow follicles, a score for the persistence of the right oviduct and bone density. In addition, body weight QTL at 3, 6, 12, 24, 48 and 72 weeks of age, QTL for growth rate between the successive ages and QTL for the parameters of the growth curve were also detected. Most of the QTL for traits at sexual maturity acted additively. A few of the QTL explained a modest proportion of the phenotypic variation with most of the QTL explaining a small component of the cumulative proportion of the variation explained by the QTL. Body weight QTL were critical in determining the attainment of puberty. The broiler allele had positive effects on weight at first egg and negative effects on age at first egg. Most QTL affecting weight at first egg overlapped with QTL for age at first egg and for early growth rate (6-9 weeks) suggesting that growth rate QTL are intimately related to the onset of puberty. Specific QTL for early and adult growth were detected but most QTL had varying influence on growth throughout life. Chromosome 4 harboured most of QTL for the assessed traits which explained the highest proportion of the phenotypic variation in the traits confirming its critical role in influencing traits of economic importance. There was no evidence for epistasis for almost all the studied traits. Evidence for role of epistasis was significant for ovary weight and suggestive for both growth rate and abdominal fat

The effects of dietary crude protein on fertility of broiler breeder males.

Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.Fertility of Broiler Breeders (BBs) has been researched over many years with inconclusive findings. Genetic selection and improvements in growth traits have had negative effects on fertility of BB. One explanation is related to overweight birds, resulting in the inability of birds to copulate successfully, with no cloacal contact. The requirements of CP for egg production in BB females have been quantified, but there is less literature on how CP affects fertility in male BBs. The objective of this experiment was to investigate the effects of feeding BB males different dietary CP intakes (10.4, 12.4, 14.2, 17.8, 19.3 and 20.1 g CP/bird/day) on fertility in flocks with natural mating and in birds that were artificially inseminated (AI). Results showed that birds consuming 10.4 and 12.4 g CP/bird/day resulted in weight loss (between 24.9 and 23.6% and 26.5 and 22.4% below target BW) over the 29 weeks of the experimental period in both natural mating and individual pens respectively. Intakes of higher protein content (17.8- 20.1 g CP/bird/day) however resulted in BW gain over the experimental period. Hatch percentage across all CP intakes throughout the duration of the study was found to be high, ranging between 75- 100 and 80-95 % in AI and naturally mated birds respectively, and not affected by CP intakes. Similar results for predicted fertility using the methods published by Brillard & Antoine (1990) and Wishart (1997) were found; however Brillard & Antoine (1990) is more lenient requiring less outer perivitelline layer (OPVL) sperm/mm2 to pronounce an egg fertile. Improved fertility predictions could have been made by using examination of inner perivitelline layer (IVPL). There was a tendency for a superior response in predicted fertility from birds with a protein intake of 14.2 g CP/bird/day. This intake also least affected the BW of the male birds and thus 14.2 g CP/bird/day can be recommended for optimal BB male performance