Effects of the age of male and female broiler breeders on sexual behaviour, fertility and hatchability of eggs

Potential of accelerometer tags for monitoring of Japanese quail (Coturnix japonica) reproductive behaviour

1. Monitoring behavioural dynamics in complex animal environments, such as poultry breeding facilities, poses a challenge. Utilising technological approaches, such as accelerometers, offers a solution to assess long-term changes in reproductive activity at an individual bird level. Specifically, these sensors measure acceleration associated with the position and movements of the body over time. However, it is important to assess the most suitable method for attaching accelerometer tags to ensure they do not negatively impact behaviour and yield high-quality data.2. The potential of tri-axial accelerometer tags for assessing reproductive behaviour in Japanese quail was evaluated. Two attachment methods - a backpack (plastic platform with elastic bands near wing bases) and a patch (accelerometer on fabric glued to the synsacrum region) - were compared. Controls were handled similarly but without tags. Eighteen pairs of females were housed in pens and assessed immediately and 24 h after handling. After a week of habituation, a male from the same treatment group was introduced into each pen on d 8. The reproductive behaviour of the males was recorded using accelerometers and video recordings.3. The results showed that birds with patches were able to remove their conspecific's accelerometer and displayed an increased initial immobility response compared to the control and backpack groups. The presence of accelerometer tags did not impact male/female reproductive interactions nor fear responses to a novel object. From accelerometer recordings, male reproductive behaviour was easily identified as high amplitude fluctuations in the three axial components of the acceleration vectors, which was reflected as large values of dynamic body acceleration (VeDBA).4. In conclusion, the use of backpacks with accelerometers is a useful strategy to address highly relevant and difficult to tackle behavioural topics such as the temporal dynamic of male reproductive behaviour within breeding groups.

Semen quality and sperm characteristics in broiler breeder cockerels fed vitamin E during hot season

Thirty-two Arbor Acres (AA) cockerels aged 27 weeks were used to determine the effect of vitamin E (VE) on the semen characteristics and sperm quality during hot season. The birds were fed diets containing 0, 50, 100 and 150mg VE kg-1 feed. There were 4 replicates and two birds per replicate. Semen collection was done thrice a week for three weeks in all birds. Dietary vitamin E significantly (p < 0.05) increased the semen volume (SV) and number of sperm cells (NS) in AA cockerels. CONTROL birds (0.71 mL) had lower SV than birds fed 150 mg VE (0.94 mL). Birds on 100 and 150 mg VE recorded similar NS, which was higher than 0 and 50 mg VE groups. The least NS was in the CONTROL group. Sperm abnormality gradually (p < 0.05) decreased as dietary VE increased from 0 to 150 mg. Significant (p < 0.01) effect of dietary VE was recorded in percentage live sperm (PLS). Semen from cockerels on VE treatment had higher PLS than the CONTROL. In conclusion, it may be beneficial to supplement the broiler breeder cockerel diet with VE up to 150 mg kg-1 feed during hot season as it increased SV, NS and PLS and decreased sperm abnormality.

In pursuit of a better broiler: welfare and productivity of slower-growing broiler breeders during lay

Current commercial strains of broiler breeders display reproductive dysregulation when fed to satiety, but they can achieve optimal hatching egg production under feed restriction. However, chronic feed restriction in broiler breeders is a welfare concern due to physiological and behavioral signs of hunger, lack of satiety, and frustrated feeding motivation. The purpose of this study was to assess the welfare and productivity of slower-growing broiler breeders during lay. A total of 336 broiler breeders from 5 strains of slower-growing broiler breeders (3 female strains: 100 hens per strain, and 2 male strains: 12 and 24 roosters per strain) were kept in 12 identical pens throughout lay, 4 pens per combination of roosters and hens: A hens with Y roosters, B hens with Y roosters, and C hens with X roosters. According to guidelines, strain B and C hens and X roosters were slower growing strains and strain A hens and Y roosters were intermediate growing strains. Egg production was recorded daily, and settable eggs laid at 30, 40, and 50 wk of age were incubated to hatch. Growth rate, feed and water intake, and welfare indicators (feeding motivation, behavior, and physical assessment: feather coverage, foot and leg health, and keel bone status) were recorded during lay. Additionally, a subsample of 5 hens per pen was dissected for anatomical analyses. Laying rate started and peaked earlier in B hens than in A hens and remained above 70% in both strains, yielding high cumulative egg production (>165 eggs/hen) until 53 wk of age. Until 50 wk of age, fertility and hatched of fertile was high in slower growing broiler breeders, on average, above 95 and 80%, respectively. Compared to A hens, B and C hens had better feather coverage, lower feeding motivation, and lower daily water and feed intake. Results of this study suggest that slower growing broiler breeders show reduced signs of poor welfare and improved productivity during lay although susceptibility to obesity-related problems on laying rate may be strain-specific.

Reproductive parameters and weight gain of roosters fed with waste oil from olive culture

Waste oil from olive oil extraction industry was used, instead of soybean oil, in heavy roosters’ diet in order to evaluate birds’ reproductive parameters. A total of forty roosters were housed individually in boxes with 1.2 m². Two experimental diets were used: control diet, based on corn, soybean meal, and soybean oil; and test diet, where soybean oil was totally replaced by waste oil. In order to verify weight gain and feed intake, animals were individually weighed weekly. Seven semen collections were performed with fifteen-day interval. Reproductive variables analyzed sperm volume, motility, concentration, and morphology. No statistical difference (p > 0.05) was observed between treatments at the different collection periods for the variables sperm volume, motility, and concentration. There was a statistically significant difference between treatments for body weight in periods three (p = 0.04), and seven (p = 0.04). Statistical differences (p = 0.01) were also observed between treatments for abnormal sperm morphology. Among collection periods, statistical difference was observed for motility (p = 0.00), and sperm concentration (p = 0.01). Total replacement of soybean oil by waste oil from olive oil extraction in young heavy roosters’ diets does not affect sperm volume, motility, and concentration; reduces defects in sperm tail, and promotes better weight gain control.

Interventions in mating strategies of broiler breeder during peak and post peak phase influence hatching traits

The study evaluated the effect of housing system, insemination frequency, and sperm concentration on hatching traits of commercial broiler breeder. Experiment was set up as 2 × 4 × 4 factorial arrangement under completely randomized design. A total of 960 broiler breeder females (Ross-308) were divided evenly (480) into two groups for Artificial Insemination in cages (AIC) and on deep litter floor (AIF) with 41 and 48 males were allocated for aforesaid flocks, respectively. Females birds of both flocks (AIC and AIF) were further divided into 4 treatment groups to apply 4 various insemination frequencies at 4, 6, 8, and 10th days. These treated groups were further divided into 4 subgroups to apply each of insemination frequencies with 4 different sperm concentrations per insemination dose 100, 125, 150, and 175 × 106 sperms during peak phase of production which were replaced with 200, 225, 250, and 275 × 106 sperms in post peak phase. According to the results, significantly higher egg production, fertility, hatchability and number of chicks were documented when AI was conducted in cages as compared to deep litter floor. Although, the best reproductive performance was observed on 4 and 6th day insemination frequencies on all subjected sperm concentrations during peak; however, these parameters were found better on only 4th day during post peak. Sperms concentrations of 150, 175 × 106 during peak and 250 and 275 × 106 during post peak brought forth the best reproductive performance on all insemination frequencies. Although, embryonic mortality was significantly higher, when AI was conducted in floored flocks particularly when repeated after 4th day; however, various sperm concentrations found inert. In conclusion, AI found advantageous in caged flock as compared to floored. The consortium of different insemination frequencies and sperms concentrations are required for sustainable reproductive traits with progression of breeder age.

Effect of different rearing system on eggs production, hatchability, and offspring quality in layer breeders

This study analyzed the influence of an aviary system, in comparison with battery cages, on rearing and reproduction of parent-stock (PS) laying-type chickens. ISA Brown PS chicks were reared for 16 wk in battery cages or in an aviary system. Chickens reared in cages were kept there throughout the rearing period, whereas those reared in the aviary were released after 7 wk. The remaining housing conditions were similar in cages and the aviary. Body weight (BW, g), feed intake (FI, g/birds/d), and mortality (%) of birds were monitored during rearing. After the rearing period, the chickens were transferred to 4 litter poultry houses: flock C (in cages) to poultry houses C1 and C2 (total: 2,076 cockerels and 20,450 pullets); flock A (in aviary) to poultry houses A1 and A2 (total: 1,542 cockerels and 16,962 pullets). During the period of reproduction (48 wk), egg production (%), hatching egg production (%), waste egg (%) and litter egg production (%), feed conversion ratio (FCR, g) and water intake (mL) per laid egg, hatching egg, and hatched chick, mortality (week/%), and BW at 17 wk and after reaching 50% laying performance were monitored. Furthermore, during incubation, fertilization rate (%), hatchability (%), and chick quality were recorded. The results showed that aviary rearing was associated with lower FI and higher mortality of chicks up to 16 wk of age. The following effects were also observed for aviary rearing during reproduction: the average egg and hatching egg production were higher, while waste and litter egg production were lower; FCR per laid egg, hatching egg, and the number of hatched chicks were poorer; and water intake for the production of 1 hatching egg and 1 hatched chick was lower. In the case of flocks A, higher mortality and BW at 17 wk of age were recorded for both sexes. They were characterized by higher relative egg fertilization, but lower hatchability due to the higher share of unhatched eggs. No influence of PS flock rearing system on chick quality was observed. The obtained results indicate that the aviary rearing system can be recommended for PS laying-type flocks. However, future research should consider the impact of a different diet having higher energy concentration on PS flocks reared in aviaries and develop methods for counteracting higher mortality in these systems. This is particularly significant for roosters because too few roosters in flock may contribute to lower egg fertilization and higher embryonic mortality.

The effect of alternative feeding strategies for broiler breeder pullets: 2. Welfare and performance during lay

Feeding broiler breeders to satiety has negative consequences on their health and reproduction. Alternative feeding strategies during rearing can improve welfare, although their implications during lay are not well understood. The objective was to examine the effect of rearing feeding treatments on the reproductive performance and feeding behavior of broiler breeders under simulated commercial conditions. At 3 wk of age, 1,680 Ross 308 pullets were allocated to 24 pens under 1 of 4 isocaloric treatments: 1) daily control diet; 2) daily alternative diet (40% soybean hulls and 1 to 5% calcium propionate); 3) 4/3 control diet (4 on-feed days, 3 non-consecutive off-feed days per week); and 4) graduated control diet. Feeding frequency of the graduated treatment varied with age and finished on a daily basis. At 23 wk of age, group sizes were adjusted to 40 hens, and 5 mature Yield Plus Males roosters were introduced to each pen. Pens were under the same daily feeding management and same diet during lay. The performance of broiler breeders (growth rate, body weight uniformity, and reproductive performance) was determined until 64 wk of age. At the end of lay, feeding motivation was examined with a feed intake test and a compensatory feeding test. Data were analyzed using linear mixed regression models, with pen nested in the models and age as a repeated measure. The laying rate of hens reared on the graduated treatment decreased slower compared to control hens, resulting in a higher cumulative egg production (178.2 ± 3.8 eggs/hen) than control hens (165.2 ± 3.8 eggs/hen, P < 0.01) by 64 wk of age. Hens reared on non-daily feeding treatments laid lighter eggs with relatively heavier yolks and had higher feed intake at the end of lay than hens fed daily during rearing (P = 0.02). In conclusion, rearing feeding treatments impacted the growth rate and body weight uniformity during lay, feeding motivation at the end of lay, and the laying rate and hatchability depending on hens' age.

Influence of male-male competition on reproductive performance and mortality of broiler breeders following intra-spiking

The study was conducted to determine the influence of male-male competition on reproductive performance and male mortality of Cobb 500 broiler breeder flocks following double intra-spiking. Broiler breeders were housed in 3 open-sided houses each accommodating 8,200 females and 820 males. Males of the same age on the same farm were exchanged between the houses (intra-spiking) to stimulate competition thereby changing the social hierarchy of each house. Intra-spiking was performed by replacing 25, 35, and 45% of males between the houses at 40 and 48 weeks of age (WOA), respectively. Eggs were collected from 36 to 55 WOA, when egg fertility and male mortality were recorded. Data was analyzed using repeated measures techniques of SAS 9.4, modeling the covariance structure of the observed data. Male-male competition (intra-spiking), age and their interaction significantly (P < 0.05) influenced egg fertility, hatchability, and male mortality. Average fertility and hatchability were increased in the 45% intra-spiked flocks (P < 0.05) (95.89 and 85.83%) compared with the 35% (95.13 and 86.30%) and 25% (94.42 and 0.23%) intra-spiked flocks. Fertility and hatchability with the 45% double intra-spiked flocks was consistently higher (P < 0.05) over time than the other double intra-spiked flocks. Male mortality was lower (P < 0.05) in the 45% intra-spiked flock (0.23%) than in the 35% (0.40%) and 25% (0.44%) intra-spiked flocks. After double intra-spiking, the male mortality in the 25 and 35% double intra-spiked flocks significantly increased (P < 0.05), whereas that of 45% intra-spiked flocks remained relatively low. Male mortality in the 45% intra-spiked flocks was consistently low over time than other double intra-spike levels from 45 WOA until the end of the trial. Noteworthy, egg fertility and hatchability gradually decreased, and mortality increased with increasing flock age toward the end of the productive life cycle. High level of male-male competition (45%) showed great promise as a tool to slow down the decrease in egg fertility and hatchability, and reduce male mortality in aging broiler breeder flocks.

Organic and inorganic selenium in Aseel chicken diets: Effect on hatching traits

A study was conducted to evaluate the effect of dietary selenium (Se) sources (organic and inorganic Se at 0.30 ppm and basal diet at 0 ppm level of supplemented Se) on hatching traits in four varieties of Aseel chicken, Lakha, Mushki, Peshawari, and Mianwali. In total, 84 adult molted hens (50 wk old), 21 from each variety, were randomly assigned to 12 treatment groups in a 3 (Se diets) × 4 (Aseel varieties) factorial arrangement under a randomized complete block design. Each treatment was replicated 7 times with individual hens in each. Settable egg, fertility, hatch of fertile eggs, hatchability, A-grade chick, and embryonic mortality parameters were evaluated. The results indicated that the birds fed an organic Se supplemented diet had greater (P < 0.05) settable eggs, fertility, hatch of fertile eggs, hatchability, and A-grade chicks and reduced embryonic mortality than those fed inorganic or no Se. Among varieties, Mushki had lower (P < 0.05) fertility, hatch of fertile eggs, hatchability, and A-grade chicks than rest of three varieties. Interaction of Se sources and varieties indicated that dietary organic Se supplementation improved (P < 0.05) hatch of fertile eggs in Peshawari and Mianwali, whereas hatchability only in Peshawari variety and reduced embryonic mortality in Mianwali. It was concluded that dietary supplementation of organic Se could be used to improve hatching traits as well as reduce embryonic mortality in native Aseel chicken.

Escores de cloaca e de crista e morfometria testicular em galos de matriz pesada com 71 semanas de idade e três categorias de peso corporal

Em galos de matriz pesada, o peso dos testículos se associa positivamente com a produção diária de espermatozoides e com a fertilidade. Contudo, os testículos de aves se localizam na cavidade abdominal, não sendo acessíveis para exame andrológico como os testículos de mamíferos. A avaliação reprodutiva de galos de matriz pesada é subjetiva e se baseia em características como peso corporal (PC), qualidade de pés e pernas e morfologia de cloaca e crista. Estudos que validem o potencial de associação dessas características fenotípicas com parâmetros da morfometria testicular são raros, principalmente quando se consideram galos de matriz pesada manejados em lotes comerciais. Escores de cloaca e de crista e parâmetros da morfometria testicular foram avaliados em galos Cobb 500 Slow adultos das categorias de PC leve (<4,300kg), médio (entre 4,300 e 5,250kg) e pesado (≥5,250kg). O coeficiente de variação para PC foi de 12%. Os galos da categoria de PC pesado apresentaram testículos mais pesados e maiores escores de cloaca e de crista do que os galos da categoria de PC leve. Não houve diferença estatística entre as categorias de PC, considerando-se índice gonadossomático, porcentagens de túbulo seminífero e de tecido intersticial, diâmetro de túbulo seminífero e altura de epitélio seminífero. Correlação positiva, moderada e significativa foi observada entre peso de testículo e características de PC, escores de cloaca e de crista, diâmetro de túbulo seminífero e altura de epitélio seminífero. Um dos seis galos da categoria de PC leve avaliados quanto à histologia de testículo apresentou atrofia testicular. Em galos Cobb 500 Slow, conclui-se que o PC influencia o peso e a qualidade histológica de testículos e que os escores de cloaca e de crista podem ser utilizados com potencial moderado de predição para identificar galos com baixo peso de testículos.

Mating activity of domestic geese ganders (Anser anser f. domesticus) during breeding period in relation to age, testosterone and thyroid hormones

In breeding geese, natural mating applies. The objective of this study was to determine seasonal- and age-related changes in the sexual activity of ganders. Moreover, T, T4 and T3 plasma levels were evaluated. The study was conducted on 2/3-year-old males (n=15) and 1- or 2/3-year-old females (1♂:4♀). Sexual activity of ganders was characterized through the frequency of: courtship, attempts at and successful copulations and total mating activity (MA). Reproductive results manifested by egg production and fertility were recorded. Laying percentage (January-June) was 37.1 and 28.6% for 1-, and 2/3-year-old geese, respectively. MA was noted before the sexual maturity of females and the T level peak. MA was highest at the onset and during peak production (March) for ganders kept with 1-, and 2/3-year-old geese, respectively. From April to May a decrease in fertility with a reduction of the frequency of copulations was observed. At this time low levels of T were noted. The effect of goose age on the MA was shown, with higher frequency of copulations for ganders kept with 1-year-old geese. We suggest that in the successful seasonal mating in geese, social factors such as the presence of females and female age play an important role. The reduction in fertility during the spring period may be associated with decreases in the efficiency of successive mating sequences. The higher frequency of copulations without affecting fertility, for ganders kept with young geese, may be because of differences in sperm transfer or storage/transport efficiency.

Heritability of embryonic mortalities in ostrich eggs and factors affecting hatching failure of fertile eggs during artificial incubation

The high rate of embryonic mortality during artificial incubation of ostrich eggs is a major concern in the ostrich industry. Data from 48 126 individual egg records were available to derive genetic parameters for embryonic mortalities, modelled as a trait of the individual egg. Embryonic mortality was classified according to stage of death, i.e. early embryonic mortality that occurred before 21 days of incubation (EEM), late embryonic mortality that occurred after 21 days of incubation (LEM) and overall embryonic mortalities (OEM). LEM increased significantly for eggs laid by females >10 years old. Transfer of eggs between incubators during incubation also impaired hatchability. An increase in OEM occurred for eggs freshly set (43%) as well as for eggs stored for more than 6 days (50%). Medium heritability (h2) estimates were derived for all the embryonic death traits and ranged between 0.16 ± 0.02 for LEM and 0.22 ± 0.03 for EEM. The dam permanent environmental effect was low ranging between 0.021 ± 0.005 for LEM and 0.046 ± 0.008 for EEM. Hatchability of fertile ostrich eggs may consequently be improved by removing older females from breeding flocks, setting of eggs between 2 and 6 days after collection, and by refraining to transfer of eggs between incubators during incubation. Moderate h2 estimates indicate that breeding may be used as a tool to enhance chick production in ostriches. This contention is supported by the fact that selected breeding for chick production and liveweight appeared to result in genetic changes in embryonic mortality rates.

Inheritance of fertility in broiler chickens

BACKGROUND

The fertility of a chicken's egg is a trait which depends on both the hen that lays the egg and on her mate. It is also known that fertility of an individual changes over the laying period.

METHODS

Longitudinal models including both random genetic and permanent environmental effects of both the female and her male mate were used to model the proportion of fertile eggs in a pedigree broiler population over the ages 29-54 weeks.

RESULTS

Both the male and the female contribute to variation in fertility. Estimates of heritability of weekly records were typically 7% for female and 10% for male contributions to fertility. Repeatability estimates ranged from 24 to 33%, respectively. The estimated genetic variance remained almost constant for both sexes over the laying period and the genetic correlations between different ages were close to 1.0. The permanent environment components increased substantially towards the end of the analyzed period, and correlations between permanent environment effects at different ages declined with increasing age difference The heritability of mean fertility over the whole laying period was estimated at 13% for females and 17% for males. A small positive correlation between genetic effects for male and female fertility was found.

CONCLUSION

Opportunities to improve fertility in broiler stocks by selection on both sexes exist and should have an impact throughout the laying period.

Feeding Broiler Breeder Males. 3. Effect of Feed Allocation Program From Sixteen to Twenty-Six Weeks and Subsequent Feed Increments During the Production Period on Body Weight and Fertility

Two experiments were conducted to compare different feed allocation programs from 16 to 26 wk of age and during the subsequent production period on broiler breeder male BW and fertility. In experiment 1, Ross 344 males were randomly assigned to 3 rates (slow, medium, or fast) of weekly feed increase from 16 to 26 wk of age that provided a gradual increase from 85 to 110 g/male/d. Feed allocation was also increased 5 g/ male/d in a single increment at 55 wk of age after fertility had declined. In experiment 2, a 2 x 2 factorial design was used to evaluate the interaction between the slow and fast feeding programs described in experiment 1 in combination with 2 feeding programs (constant or increasing) during the subsequent production period. In experiment 1, the males on the fast feed program exhibited higher mortality after 32 wk of age and lower fertility after 46 wk of age. However, fertility recovered in all treatments after the feed allocation was increased at 55 wk of age. In experiment 2, the constant program elicited lower fertility from 36 to 55 wk. Males that received the slow feed program from 16 to 26 wk of age gained BW more slowly and apparently required less feed to sustain their BW throughout the production period. Increasing male feed allocation during the production period improved fertility.

Effects of Ipriflavone on Caged Layer Bone Metabolism In Vitro and In Vivo

The effects of ipriflavone on caged layer bone metabolism were examined in vitro and in vivo. Ipriflavone at 10(-8) M stimulated the activity of osteoblasts cultured from embryonic chick calvariae, and 10(-9) to 10(-7) M inhibited osteoclasts from chick tibias and humeri. Ipriflavone concentrations of 10(-4) and 10(-5) M inhibited osteoblast activity. These results suggest that ipriflavone influences bone metabolism by regulating the functional balance between osteoblasts and osteoclasts. Based on these in vitro experiments, in vivo studies were conducted to further clarify the effects of ipriflavone. Five hundred 58-wk-old ISA caged layers were divided into 5 groups that were fed diets containing 0, 15, 25, 50, and 100 ppm of ipriflavone. The experiment lasted 70 d. Egg production increased in hens fed 25 ppm and decreased in hens fed 50 and 100 ppm when compared with the controls and hens fed 15 ppm (P < 0.05). Egg weight, shell quality, BW, and serum P, Ca, estrogen, and bone mineral content were not affected by inclusion of ipriflavone in the diet. Hens consuming 25 ppm of ipriflavone had greater serum alkaline phosphatase and bone gla-protein levels than controls. Adding 25 ppm of ipriflavone to the feed appears to be close to an ideal level for clinical treatment of osteoporosis because of improved egg production while maintaining bone mineral content.

Feeding Broiler Breeder Males. 1. Effect of Feeding Program and Dietary Crude Protein During Rearing on Body Weight and Fertility of Broiler Breeder Males

A 2 x 2 factorial experiment was conducted to compare the effects of 2 male broiler breeder feed allocation programs (Concave or Sigmoid) during the rearing period to 26 wk of age and the interaction with dietary CP (12 or 17%) on BW and fertility. From 0 to 2 wk, all birds received a starter diet, after which, pens were randomly assigned to the 4 treatment combinations that ended at 26 wk of age. All males were weighed individually at 4, 8, 12, 16, 22, 26, 28, 32, 36, 40, 48, 52, 56, and 64 wk of age, and fertility was determined weekly from 27 to 32 wk of age and then every 2 wk to 64 wk of age. At 49 wk of age, the male feed allocation for all treatments was increased by 5 g/d. Even when fed the same as Sigmoid program males during the production period, males reared on the Concave feeding program lost BW from 32 to 40 wk of age and exhibited lower BW from 40 to 48 wk of age, which corresponded to a more rapid decrease in fertility. The 17% CP diet increased BW from 8 to 32 wk of age, but no significant differences were subsequently observed. The 12% CP rearing diet improved both weekly and cumulative fertility. A significant interaction between rearing feeding program and dietary CP during the third quartile period showed that the Concave program-17% CP diet combination was most negatively affected. The increase in male feed allocation at 49 wk restored fertility and caused differences among treatments to diminish. These data suggested that BW during the early rearing period did not affect fertility, but an increased BW due to either providing fast feed increments toward the end of the rearing period (Concave) or feeding a 17% CP diet produced males that were unable to sustain fertility after 40 wk of age without an appropriate allocation of feed.

Effects of Supplementing Broiler Breeder Diets with Organoselenium Compounds and Polyunsaturated Fatty Acids on Hatchability

The effects of supplementing broiler breeder diets with polyunsaturated fatty acids (PUFA) and organoselenium compounds on fertility, hatchability, and the weight of 1-d-old chicks was assessed. Prepeak (23 wk) and peak (27 wk) production breeders were fed 1 of 4 diets: a wheat-based commercial breeder diet with 55 g/kg of either soybean oil (SO) or fish oil (FO), but no added Se (only that originating from feed ingredients), and each diet with added Se as Sel-Plex (SO + Se, FO + Se). The diets were designed to contain <0.1 mg/kg of Se and about 0.5 mg/kg of Se for the nonsupplemented (no added Se) and the supplemented diets, respectively. The Se concentration of the eggshell of the hatching egg was measured. The concentration of Se, PUFA, and total lipid content of the brain and liver of the 1-d-old chick was determined. The number of fertile eggs increased, embryonic mortality decreased, and hatchability increased as hen age increased from 23 to 27 wk. The Se concentration in the eggshell and the brain and liver of 1-d-old chicks was higher in the high-Se treatments com pared with the concentration in the low-Se treatments. Fish oil inclusion in the breeder diet increased embryonic mortality in wk 3 of incubation and reduced both hatchability and 1-d-old chick weight in hens of both ages. The addition of Se to the FO diets ameliorated some of these adverse effects, because chicks hatched from eggs laid by 23-wk-old breeders of the FO + Se treatment were heavier than those receiving the FO treatment. The Se concentration in the brain and liver of chicks from the FO hens was higher than that in chicks from the SO hens. The concentration of docosahexaenoic fatty acid was higher in the liver of chicks from the SO + Se treatment compared with that of chicks from the SO treatment, indicating possible protective effects of Se. Hatchability was decreased by increased PUFA and was higher in 27-wk-old compared with 23-wk-old breeders.

Can testosterone and corticosterone predict the rate of display of male sexual behaviour, development of secondary sexual characters and fertility potential in primary broiler breeders?

1. Genetic selection for growth to enhance production may be associated with stress and with modified physiological and behavioural phenotypes which depress male primary broiler breeder fertility. 2. We hypothesised that male serum testosterone (T) and corticosterone (C) concentrations might correlate with fertility, sexual behaviour, and testicular, comb and wattle size. 3. Cockerels from two genetic strains (A and B) of primary broiler breeder were penned individually with an average of 10 females across 5 age periods (30 to 51 weeks) to evaluate male fertility, behaviour, serum T and C, and comb, wattle and testicular dimensions. 4. Strain A males had higher T at age periods 2, 4 and 5 than Strain B. Both strains had basal concentrations of C, apart from an elevated concentration for Strain B in period 5. 5. Strain B had a weak but significant, positive correlation between sexual behaviour and T and C, while Strain A males with higher C had larger combs and wattles. 6. Neither T nor C correlated with fertility. We conclude that evaluation of these endocrine factors (quantifiable measurements with the potential to correlate with fertility) alone seems insufficient to predict male fertility potential in these strains of primary broiler breeder.

Observations on the patterns of embryonic mortality over the laying season of pheasants

1. Embryonic mortality of domestic pheasant (Phasianus colchinus) eggs was recorded for a 10-week laying season for two groups of laying hens maintained under mating ratios of 8:1 and 12:1 (females:males). 2. Mating ratio had no significant effect on embryonic mortality between 1 and 4 or 5 and 20 d but values for these categories doubled as the laying season progressed, both rising to 8% to 9% of fertile eggs. 3. Higher embryonic mortality was observed between 21 and 25 d for the eggs from the 8:1 mating ratio (14.5% of fertile eggs compared with 12.1%) but this was unaffected by week of setting. 4. Reasons for these patterns of embryonic mortality were not clear and further research is needed to determine the factors affecting embryonic mortality in pheasants.