Photoperiodic response curves for plasma LH concentrations and age at first egg in female broiler breeders

Lewis, P. D.; Tyler, N.C.; Gous, R. M.; Dunn, Ian; Sharp, P. J.

doi:10.1016/j.anireprosci.2008.02.012

Cited by 15 publications

(16 citation statements)

References 22 publications

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“…Photostimulation at three weeks of age, in feed-restricted birds, resulted in significantly higher plasma luteinising hormone (LH) concentrations compared to non-photostimulated control birds. However, this may South African Journal of Animal Science 2009, 39 (3) © South African Society for Animal Science 170 not translate to a different ASM as Lewis et al (2005) concluded that changes in plasma gonadotrophins were not particularly useful as predictors of ASM, although a photoperiodic response curve, where a plot of the photo-induced increase in plasma LH against a range of photoperiods after photostimulation, is useful in predicting the critical and saturation daylengths (Lewis et al, 2008). The aim of the experiment reported here was to determine the response of male broiler breeders to different ages at photostimulation, through testes development and asymmetry as well as age at first semen production and serum testosterone concentration, and to determine whether flock fertility may be maximised if males are reared on the same lighting programme as females.…”

Section: Introductionmentioning

confidence: 99%

The effect of age at photostimulation of male broiler breeders on testes growth and the attainment of sexual maturity

Tyler

Gous

2009

SA J. An. Sci.

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________________________________________________________________________________ AbstractMale broiler breeders were photostimulated at different ages (56, 77, 98, 119, 147 and 161 d) during the period of growth prior to achieving sexual maturity to observe their response to photoperiod stimulation. Birds were sampled at regular intervals to measure the average testis weight -these values responding curvilinearly to the age at photostimulation, similar to the attainment of sexual maturity observed previously in females. However, males reached sexual maturity at an earlier age than females, as measured by the start of semen production. Based on the age at first semen production, no differences in the mean age at sexual maturity (ranging from 164 to 172 d) resulted from the different ages at photostimulation. Testis weights from males on different photostimulation treatments showed that some males respond to early stimulation, but from 189 d of age some of these early photostimulated males still had an average testis weight of less than 10 g, while males photostimulated 98 d and later all had an average testis weight over 10 g. Serum testosterone concentration measured at 351 d also showed that early photostimulation resulted in two groups of birds that either responded or not. At 351 d the serum testosterone concentration was more evenly distributed in males photostimulated after 98 d, while males photostimulated before 98 d had either high or low serum testosterone concentrations. Directional asymmetry was observed in testis weights, with the left testis being bigger than the right. Other bilateral traits measured also showed directional asymmetry, an indication of developmental instability. However, the degree of relative asymmetry was not related to treatment. All males should respond to photostimulation by 98 d but some respond earlier, and these could be used by broiler breeding companies to eliminate seasonality in these birds. ________________________________________________________________________________

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Section: Introductionmentioning

confidence: 99%

The effect of age at photostimulation of male broiler breeders on testes growth and the attainment of sexual maturity

Tyler

Gous

2009

SA J. An. Sci.

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“…The age at first semen production of males on different photoperiodic treatments was subjected to an analysis of variance, despite lack of replication, to be able to compare age at sexual maturity results to those obtained by Lewis et al (2008) for females. Standard curve regression analysis was used to obtain the relationship between sperm concentration and photostimulation photoperiod.…”

Section: Methodsmentioning

confidence: 99%

“…At the corresponding reported female age at first egg from females on the same treatments (Lewis et al, 2008), digital photographs were taken of the left and right side of the head of each male. Each picture contained a centimetre ruler for image calibration and the computer mouse was used to trace the perimeter of the comb in the digital photograph of the clearest side of each bird in order to calculate the comb area using image analysis software (Rasband, 2006).…”

Section: Methodsmentioning

confidence: 99%

“…Two days prior to the corresponding reported mean age at first egg of females on the same treatment (Lewis et al, 2008), semen was collected from the male birds, using a modified version of the method of Lake (1957), and assessed for concentration, motility and morphology, and the number of days in production. The difference between the first semen production to the corresponding reported mean age at first egg of females on the same treatment (Lewis et al, 2008) was calculated. Sperm concentration was measured with the use of a haemocytometer.…”

Section: Methodsmentioning

confidence: 99%

“…The critical daylength (photoperiod required to effect a change) in dwarf broiler breeders was found to be less than 10.5 h and the saturation daylength (photoperiod above which no further advance in maturity is observed) was between 10.5 and 12.75 h (Dunn & Sharp, 1990). Lewis et al (2008) determined the critical and saturation daylengths more accurately in female broiler breeders as 9.5 and 13 h, respectively. The onset of adult photorefractoriness appears to be advanced in broiler breeders maintained on long days (Lewis et al, 2003; or if photoperiodic increments are provided during lay (Lewis & Gous, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Photostimulation of male broiler breeders to different photoperiods

Floyd¹,

Tyler²

2011

SA J. An. Sci.

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________________________________________________________________________________ AbstractThe effect of photostimulation of male broiler breeders (n = 144) to different photoperiods (8-h control and 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 14 and 18 h) applied at 20 weeks of age, on age at first semen production, testis weights, as predicted by comb area, and semen characteristics at the reported age at first egg of females provided the same photostimulation photoperiods, as well as semen characteristics during the production cycle and comb area and testis weights at 51 weeks, was investigated. Photostimulation photoperiod did not affect age at first semen production, sperm motility, morphology or predicted testis weights. Sperm concentration, at the reported age at first egg of females on the same photostimulation photoperiod, decreased with increasing photostimulation photoperiod. Large variation in the male response to photostimulation was observed, however, photostimulation to 12 h or higher resulted in reduced variation in the age at first semen production. Males provided with the longer photostimulatory photoperiods had smaller testis weights at 51 weeks of age, although this was not associated with decreased sperm concentration, increased abnormal sperm morphology or reduced comb area. When male and female broiler breeders are reared on the same lighting regimen, initial male reproductive potential is not adversely affected, provided that the photostimulation photoperiod does not exceed the saturation daylength of 13 h, above which, sperm concentration is lower at the reported female age at first egg, which could negatively affect egg fertility near peak production, and the onset of adult photorefractoriness appears to be advanced, which could negatively affect egg fertility towards the end of production.________________________________________________________________________________

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Effects of short light regimes and lower dietary protein content on the reproductive performance of White Roman geese in an environment-controlled house

Chang

Chiang

Lin

et al. 2016

Animal Reproduction Science

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Photoperiodic response curves for plasma LH concentrations and age at first egg in female broiler breeders

Cited by 15 publications

References 22 publications

The effect of age at photostimulation of male broiler breeders on testes growth and the attainment of sexual maturity

The effect of age at photostimulation of male broiler breeders on testes growth and the attainment of sexual maturity

Photostimulation of male broiler breeders to different photoperiods

Effects of short light regimes and lower dietary protein content on the reproductive performance of White Roman geese in an environment-controlled house

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