Attainment Of Sexual Maturity Research Articles

Reproductive biology of male common dolphins (Delphinus delphis) in New Zealand waters

Reproductive parameters were assessed in 64 male common dolphins (Delphinus delphis) examined post-mortem from strandings and bycatch in New Zealand between 1999 and 2020. The stages of male sexual maturation were assessed using morphological measurements and histological examination of testicular tissue. Age was determined via growth layer groups (GLGs) in teeth. The average age (ASM) and length (LSM) at attainment of sexual maturity were estimated to be 8.8 years and 198.3 cm, respectively. Individual variation in ASM (7.5–10 years) and LSM (190–220 cm) was observed in New Zealand common dolphins. However, on average, sexual maturity was attained at a similar length but at a marginally younger age (< 1 year) in New Zealand compared to populations in the Northern Hemisphere. All testicular variables proved better predictors of sexual maturity compared to demographic variables (age and total body length), with combined testes weight the best outright predictor of sexual maturity. Reproductive seasonality was observed in male common dolphins, with a significant increase in combined testes weight in austral summer. This aligns with most other studied populations, where seasonality in reproduction is typically observed. Given the known anthropogenic impacts on New Zealand common dolphins, we recommend that these findings be used as a baseline from which to monitor population-level changes as part of conservation management efforts.

Biology of the epigeic earthworm, Eisenia fetida in different organic wastes

Aim: A study was undertaken to know the influence of different organic wastes on the biology of the epigeic earthworm, Eisenia fetida. Methodology: Epigeic earthworm, Eisenia fetida was selected and collected. Organic wastes (Corn stover, Delonix regia and Eichhornia crassipes) which are abundant and locally available were collected and used as feed materials along with cattle manure as control in this experiment. Results: The minimum incubation period and the maximum number of hatchlings per cocoon were observed in cattle manure (Control) as compared to other organic wastes. Percent cocoon hatching was 100% in all organic wastes, including control. The weight of freshly emerged juvenile was almost same in all organic wastes with no significant variations. The worm biomass was maximum in Eichhornia crassipes, whereas growth rate, attainment of sexual maturity and rate of cocoon production was maximum in cattle manure followed by other organic wastes. Interpretation: A successful vermitechnological process not only depends on the type of organic waste, but also depends on the biology of earthworm species. Based on the results, it can be concluded that epigeic earthworm, Eisenia fetida can be efficiently used in the vermitechnological process for organic waste management so as to maintain the balanced ecosystem. Key words: Eisenia fetida, Epigeic earthworm, Organic wastes, Vermicompost, Worm biology

Dentinal growth layer counts of captive, known-age, mother and daughter belugas (Delphinapterus leucas): confirming two growth layer groups (GLG/2) per year; consequences for recovery and management

Captive mother and daughter belugas (Delphinapterus leucas) of Hudson Bay origin died at the Vancouver Aquarium, in November 2016, aged29.25 and 21.25 years. Aurora, captured at age three and captive since 1990, gave birth to Qila in 1995. Age and histories being known, the focusof this study was on total number of tooth growth layer groups (GLGs) present; one (GLG/1) or two (GLG/2) per year. Teeth from Aurora indicatedtwo growth layers per year (GLG/2) during pre-capture and captivity. Qila deposited GLG/2 throughout her captive life. Clearly an assumption ofGLG/1 over GLG/2 doubles the duration of all life stages, including lifespan and age at attainment of sexual maturity. Arguments for GLG/1 havebeen based on inferences (e.g. from fallout of bomb radio carbon) from adults of unknown age and history, while those for GLG/2 are based on theprojection of direct observations from newborn, known-age young to 21 and 29 year-old adults from captivity. Use of radiocarbon is ingenious butsuch analyses have not been rigorously tested on marine mammals and the sensitivity to necessary correction factors not addressed. The newinformation from this study contradicts the GLG/1 hypothesis in that such an assumption would place Aurora’s birth at the 1958 peak fallout ofbomb radiocarbon (14C) yet she was born 29 years later in 1987, while the birth of her daughter Qila would pre-date the birth of her mother by 13years. This paper re-assesses three studies that assigned GLG/1 based ages to older adults using GLG/2 and concludes that their supposed birthswould also pre-date the realistic births of their own mothers plus as many as two previous generations. Proponents of GLG/1 have overestimatedthe ages of previous calves-at-capture by 200–800%. Given the growth pattern in teeth of these 21 year and 29 year old female belugas, withincreasingly finer dentine GLGs deposited as the pulp tissue diminishes, it is difficult to envisage the GLG/1 tooth structures of those assumed tobe 60–80 years; none are as yet available. An holistic analysis using direct observations and cross-referenced parameters does not substantiateGLG/1which implies a 40% reduction of the intrinsic rate of natural increase; as a consequence, overestimating historical population size as wellas recovery target population and the predicted date of recovery in Cumberland Sound.

Assessing the size at maturity, spawning, and condition of the truncate soft-shell clam (Mya truncata) of southern Baffin Island, Nunavut, Canada.

The truncate soft-shell clam Mya truncata is an important source of country food for Inuit communities across the territory of Nunavut, Canada. M. truncata also plays an important role in marine ecosystems, yet there is little understanding of their life history and condition in Canadian Arctic waters. To provide a foundation on which aspects of the life history and condition of M. truncata of Baffin Island can be monitored in the future with a changing climate and fishery development, this study estimated size at maturity and provides insights into the spawning cycle and weight-length condition indices of clams from inner Frobisher Bay and the north shore of the Hudson Strait. Male and female M. truncata exhibited similar lengths at 50% attainment of sexual maturity, 31 mm and 32 mm shell length (SL), respectively. Most (77%) of the sexually mature M. truncata collected from inner Frobisher Bay in late August and 35% of clams collected from the Hudson Strait in early September were in the ripe stage of gonadal development. These results lead us to suggest a spring spawning season and that M. truncata invest in gonadal development for the next year’s spawning during the late summer-early autumn ice-free season while phytoplankton concentrations are high. Dry bodyweight-SL relationships were used to show that M. truncata condition can differ significantly over small and large spatial scales based on plotted 95% confidence intervals.

BIOLOGY OF THE EPIGEIC EARTHWORMS IN TROPICAL WET AND DRY CLIMATE OF DHARWAD (KARNATAKA), INDIA

Studies on biology of epigeic earthworms is very much necessary for the selection of suitable earthworm species in effective organic waste management through vermiculture and vermicomposting process for the production of quality and quantity worm biomass (vermiprotein) and vermicompost (biofertilizer). Hence, the present study was undertaken to study the biology of different epigeic earthworm species such as Eudrilus eugeniae (EE), Eisenia fetida (EF) and Perionyx excavatus (PE) cultured in cattle manure at tropical wet and dry climate of Dharwad district, Karnataka state, India. The results of the present study revealed that the incubation period or the time of emergence of juveniles from the cocoon was less (16.33±0.53 days) in Perionyx excavatus as compared to Eudrilus eugeniae (22.33±0.73 days) and Eisenia fetida (24.33±0.88 days). The percent hatching of cocoon was more in E. eugeniae (86.66±6.66) followed by E. fetida (73.33±5.33) and P. excavatus (66.66±4.66), whereas number of hatchling/cocoon was more in Eisenia fetida (2.66±0.33) followed by Eudrilus eugeniae (2.33±0.28) and less in Perionyx excavatus (1.33±0.23). The mean weight of juvenile (mg) at the time of hatching was more in EE (7.90±0.20) followed by EF (7.00±0.57) and less in PE (5.70±0.35). The attainment of sexual maturity was observed early during 6th -9th week in EF and PE, but it was late in EE during 7th -10th week and commencement of cocoon production was noticed soon after one or two week of maturity i.e. from 8th week onwards. It was continuous and multimodal in nature with slight decline in the growth rate after maturity and cocoon production in all three epigeic earthworm species (EE, EF and PE). The various life activities such as incubation period and number of hatchling, maturity were more in EF as that of EE and PE, whereas percent hatching and juvenile weight were more in EE followed by EF and PE. Therefore, the success of vermiculture and vermicomposting process for the production of quality and quantity worm biomass (vermiprotein) and vermicompost (biofertilizer) is mainly depends on the biology or life cycle of the epigeic earthworms, type of organic waste materials used and it also depends on the prevailing abiotic factors.

Age, growth, and sexual dimorphism of the Southern Hemisphere long-finned pilot whale (Globicephala melas edwardii).

Knowledge of population biological parameters can contribute to assessing the resilience of a population in the face of increasing anthropogenic pressures. Southern Hemisphere long-finned pilot whales (Globicephala melas edwardii) are susceptible to high rates of live stranding-related mortality. However, the biological parameters of this population largely are unknown. In this study, age, growth, allometry, and sexual dimorphism are described using teeth and external body measurements obtained from 515 male, 776 female, and 229 individuals of unknown sex, stranded on the New Zealand coastline between 1948 and 2017. Maximum ages of 31 and 38 years were estimated for males (n = 163) and females (n = 239), respectively. Females ranged in length from 160 to 500 cm (modal size class 400–449 cm) and males from 165 to 622 cm (modal size class 500–549 cm). Length-at-birth for both sexes was estimated at 170 cm using a logistic regression model. Growth models for both sexes indicated a preliminary rapid growth phase followed by a second phase of slower growth. For males, a two-phase growth model also indicated a moderate growth spurt around the average age at attainment of sexual maturity (ca.12–13 years). Asymptotic lengths were estimated at 570 and 438 cm for males and females, respectively. We found strong evidence of sexual size dimorphism, with males significantly larger than females for 13 of 14 external measurements. We also found sexual dimorphism with respect to shape, with males having proportionally longer pectoral fins, wider tail flukes, and taller dorsal fins, than females. Estimates of length-at-birth, maximum ages, and sexual shape dimorphism for G. m. edwardii differed from those previously reported for the North Atlantic subspecies (G. m. melas), which may indicate subspecies or population-level differences in morphology, longevity, and sociality.

GROWTH AND REPRODUCTION OF THE EPIGEIC EARTHWORM, EISENIA FETIDA (SAVIGNY, 1826) CULTURED IN VARIOUS ORGANIC WASTES

: The study was carried out to evaluate the influence and suitability of various organic wastes on growth and reproduction of the epigeic earthworm, E. fetida maintained at uncontrolled laboratory environmental conditions. There was a much variation in biomass, growth rate and cocoon production by this earthworm in different organic wastes such as False Ashoka Waste-FAW (Polyalthia longifolia), Parthenium Waste- PW (Parthenium hysterophorus), Cotton Residue Waste- CRW (Gossypium), Lawn Grass Waste- LGW (Agrostis) and Control- Cattle manure-CM used in these experiments. The mean maximum (923.54 ±1122.59) and minimum (481.47±56.13) biomass of worm was observed in PW and FAW respectively. The mean growth rate of worm was 6316.10±529.36, 11836.00±1086.30, 9053.00±807.22, 6969.00±582.42, 10842.00±1011.50 observed in FAW, PW, CRW, LGW and CM (control) respectively. There is a significant variation (P0.05) in both worm biomass and growth rate of worms was observed among all the organic wastes, whereas no significant variation was noticed in between different organic wastes, except between PW &amp; FAW, CM &amp; FAW, LGW &amp; PW and CM &amp; LGW in biomass and between LGW &amp; FAW; CM &amp; PW and CM &amp; CRW in growth rate respectively.&#x0D; The attainment of sexual maturity and 100% maturity was observed early in Control-CM on 6 th week and 8th week followed by all other organic wastes on 7 th week and 9th week respectively. The maximum cocoon production worm/week was observed in Control-CM with 2.86±0.37 followed by CRW (2.16±0.30), PW (2.11±0.30), FAW (1.95±0.27) and it was least in LGW (1.28±0.18). The cumulative cocoon number (CCN)/worm for 17 weeks was 33.27, 35.95, 36.77, 21.77, and 48.65 in FAW, PW, CRW, LGW, and CM respectively. Significant difference (P0.05) was also noticed in cocoon production among and between different organic wastes, except between PW &amp; FAW, CRW &amp; FAW and CRW &amp; PW. Based on the results, it can be concluded that biomass, growth rate, attainment of sexual maturity and cocoon production of the epigeic earthworm, E. fetida were influenced much by different organic wastes, that inturn affect on the production of quantity and quality vermicompost and worm multiplication during vermicomposting process. This work also suggests that epigeic earthworms are very much choosy in selection of particular type of organic wastes for their growth, development and cocoon production

Reproductive Characteristics of the Kulzer’s Rock Lizard Phoenicolacerta kulzeri (Reptilia: Lacertidae)

The present study aims to determine, by histological examination, the female reproductive cycle of specimens of Kulzer’s rock lizards collected in a mountainous region in Lebanon. Females of Phoenicolacerta kulzeri followed a seasonal reproductive pattern. Winter hibernation period lasted for 5 months. Females of P. Kulzeri exhibited a reproductive activity during spring characterized by the presence of vitellogenic follicles in the ovaries and eggs in the oviducts. Oviposition occurred throughout the springtime. Up to two clutches were produced with an average clutch size of 2.9 eggs. Clutch size was significantly correlated to female body size. The attainment of sexual maturity was at a minimum size of 46 mm snout-vent length. The mean body size of adult females was 55.0 mm and did not differ significantly from that of adult males. Females showed a period of sexual rest in summer and none of them showed a reproductive activity in autumn. The female reproductive activity of P. kulzeri was well-synchronized with that of the males in spring; however, an autumnal asynchrony was observed between the female and male reproductive cycles, since males continued to exhibit a spermatogenetic activity.

Bone remodeling in the longest living rodent, the naked mole-rat: Interelement variation and the effects of reproduction.

The pattern of bone remodeling of one of the most peculiar mammals in the world, the naked mole-rat (NMR), was assessed. NMRs are known for their long lifespans among rodents and for having low metabolic rates. We assessed long-term in vivo bone labeling of subordinate individuals, as well as the patterns of bone resorption and bone remodeling in a large sample including reproductive and non-reproductive individuals (n=70). Over 268 undecalcified thin cross-sections from the midshaft of humerus, ulna, femur and tibia were analyzed with confocal fluorescence and polarized light microscopy. Fluorochrome analysis revealed low osteogenesis, scarce bone resorption and infrequent formation of secondary osteons (Haversian systems) (i.e., slow bone turnover), thus most likely reflecting the low metabolic rates of this species. Secondary osteons occurred regardless of reproductive status. However, considerable differences in the degree of bone remodeling were found between breeders and non-breeders. Pre-reproductive stages (subordinates) exhibited quite stable skeletal homeostasis and bone structure, although the attainment of sexual maturity and beginning of reproductive cycles in female breeders triggered a series of anabolic and catabolic processes that up-regulate bone turnover, most likely associated with the increased metabolic rates of reproduction. Furthermore, bone remodeling was more frequently found in stylopodial elements compared to zeugopodial elements. Despite the limited bone remodeling observed in NMRs, the variation in the pattern of skeletal homeostasis (interelement variation) reported here represents an important aspect to understand the skeletal dynamics of a small mammal with low metabolic rates. Given the relevance of the remodeling process among mammals, this study also permitted the comparison of such process with the well-documented histomorphology of extinct therapsids (i.e., mammalian precursors), thus evidencing that bone remodeling and its endocortical compartmentalization represent ancestral features among the lineage that gave rise to mammals. It is concluded that other factors associated with development (and not uniquely related to biomechanical loading) can also have an important role in the development of bone remodeling.

Body size, age and growth in males populations of Boana pulchella (Anura, Hylidae).

Age determination in amphibians is crucial to the investigation of life-history traits. In this context, we studied, for the first time, the life-history traits of Boana pulchella from a sample (63 adult males) of three populations (Las Acequias, Río Cuarto, Alejandro Roca) in central Argentina using the skeletochronological method. All adults of B. pulchella studied showed recognizable bone structures that allowed age determination. The average snout-vent length of sexually mature males was 43.39 mm. The maximum observed longevity was 5 years (5 Las Acequias, 4 Río Cuarto, 3 Alejandro Roca) and minimum age at sexual maturity was 2 years (same in the three populations), with mean of 2.96 years. Body size and age were positively correlated (except in Alejandro Roca populations). The growth patterns, estimated by the von Bertalanffy growth equation, do not show differences between populations, and the growth rate decrease after the attainment of sexual maturity. In conclusion, the determination of the individual age of the different populations of B. pulchella allowed us for the first time to establish the characteristics of the life history of the species, important for future comparisons whit others populations and future conservation biology studies.

Temporal and spatial variability in the life-history of the surf clam Donax deltoides: Influences of density dependent processes

This study aimed to determine if population dynamics and demography of the sandy beach bivalve, Donax deltoides, varied under different levels of biomass. To achieve this, population parameters for D. deltoides in south-eastern Australia were compared across a range of spatial and temporal scales during periods of low-moderate and high relative biomass. Estimates of relative harvestable biomass were lower in 2008–12 (2.3 ± 0.03 kg m2), compared to 2013–17 (3.7 ± 0.11 kg m2; P < 0.001), and also differed among years (P < 0.001), and 3 month periods within years (P < 0.001), although there was no difference between repeated days. Relative biomass also varied across six, 10 km sections of the 60 km study area with the central third of the study area relatively stable among years and the north-western and south-eastern thirds more variable. Mean and maximum length of D. deltoides varied across temporal and spatial scales similar to those of relative biomass. Growth performance in 2008–12 (φ’ = 3.32) was higher than that in 2013–17, (φ’ = 2.99) although the difference was not statistically detectable (P > 0.05). Instantaneous mortality (Z) also differed between 2008–12 and 2013–17 (P < 0.05). High relative biomass in 2013–17, following successive years of successful recruitment, occurred contemporaneously with decreased growth performance and likely suppression of subsequent recruitment, suggesting possible density dependence and growth over-compensation. Reduced growth rates under higher relative biomass imply that attainment of sexual maturity may be delayed, or alternatively maturity may occur at a smaller size, both of which have implications for individual lifetime egg production. Improved understanding of population dynamics, demography and exploitation patterns across a range of temporal and spatial scales has important implications for implementation of spatially explicit management.

Limb-Bone Development of Seymouriamorphs: Implications for the Evolution of Growth Strategy in Stem Amniotes

Tetrapod life on land was the result of a lengthy process, the final steps of which resulted in full independence of amniotic tetrapods from the aquatic environment. Developmental strategies, including growth rate and the attainment of sexual maturity, played a major role in this transition. Early amniotes, such as Ophiacodon, tended to reach sexual maturity in a year while most non-amniotic Paleozoic tetrapods (including Devonian tetrapods and temnospondyls) became adult after 3 to 11 years. This ontogenetic transition is accompanied by a drastic change in growth rate and bone microstructure suggesting faster growth dynamics in early amniotes than in Devonian tetrapods and temnospondyls. Was the acquisition of a faster development (earlier sexual maturity and faster growth rate) a drastic evolutionary event or an extended process over geological time? To answer this question, the limb bone histology of two Early Permian (i.e. 270-290 million-year-old) stem-amniote seymouriamorphs, Seymouria sanjuanensis and Discosauriscus austriacus, were investigated. We used three-dimensional bone paleohistology based on propagation phase-contrast synchrotron microtomography. Both seymouriamorphs display relatively fast bone growth and dynamics (even though cyclic in the humerus of D. austriacus). This significantly contrasts with the slow primary bone deposition encountered in the stylopods of temnospondyls and Devonian (i.e. 360 million-year-old) stem tetrapods of similar sizes. On the basis of skeletochronological data, the seymouriamorph D. austriacus retained a long pre-reproductive period as observed in Devonian tetrapods and most temnospondyls. The combination of characteristics (faster growth rate but long pre-reproductive period) suggests that the shift towards an amniotic developmental strategy was an extended process in the evolutionary history of amniotes.

Life history parameters and diet of Risso's dolphins, Grampus griseus, from southeastern South Africa

AbstractThe life history of Risso's dolphins (Grampus griseus) remains poorly known and data from strandings can help provide important information. Data from 126 Risso's dolphins stranded or bycaught along the southeastern coastline of South Africa between 1958 and 2017 were analyzed in relation to their sex, age structure, and diet. Mean estimated length at birth was 146.9 cm, while maximum length was 325 cm for males and 313 cm for females; small sample sizes precluded detailed examination of sexual dimorphism. Age estimates for 33 individuals (14 males, 17 females, 2 unknown sex) indicated a maximum age of 13 years (males) and 17 years (females), respectively; the oldest animal was 19 years (unknown sex). Mean length and age at attainment of sexual maturity were estimated at 280 cm and 7.1 years in males and at 282 cm and 7.7 years in females. Stomach contents from 27 individuals showed that diets of immature and mature males and females overlapped and consisted predominantly of cephalopods. Reported strandings decreased between 2000 and 2017, possibly due to a lack of reporting associated with a ban on driving on beaches or related to the collapse of the local “chokka” squid (Loligo reynaudii) fishery in 2014–2015.

Age, mating status and sex influence food consumption and utilization efficiency of Parthenium beetle, Zygogramma bicolorata Pallister

A study was designed to evaluate the combined effects of age, mating status and sex on the feeding attributes of the Parthenium beetle, Zygogramma bicolorata Pallister when fed on Parthenium hysterophorus L., a serious weed of wastelands, pastures and agricultural fields. Newly emerged adult beetles were placed in two groups. Adults of the first group were kept unmated and their daily feeding and growth attributes were assessed for the following 20 days. By comparison, males and females of the second group were allowed to mate on the 11th day (attainment of sexual maturity) and mating pairs were kept individually to assess their daily feeding and growth attributes for the following 10 days. Results revealed higher consumption and growth rates of Z. bicolorata females than males. In contrast, males exhibited higher food conversion efficiencies than the females. However, food consumption and growth rates of unmated adults were higher than mated adults. Agebased regression graphs revealed decreased consumption rates, conversion efficiencies and growth rates of Z. bicolorata adults with increase in age. However, the mean body biomass of adults increased with increasing age. This further suggested compensatory feeding in Z. bicolorata adults as they age. The present findings may be helpful to mass-multiply Z. bicolorata in laboratories for the biocontrol of Parthenium weed in agricultural farms on the Indian subcontinent.

Blood lead levels and timing of male sexual maturity: A longitudinal study of Russian boys

BackgroundHigher blood lead levels (BLLs) have been linked to neurologic deficits and impaired growth, but few studies have evaluated their association with timing of sexual maturity or pubertal progression in boys. MethodsIn a longitudinal cohort of Russian boys enrolled at age 8–9 and followed to adulthood, BLLs were measured at study entry, and pubertal staging (genitalia and pubic hair) and testicular volume (TV) measurements were obtained annually. We used interval-censored regression models to estimate differences between boys with higher BLL (≥5 μg/dL) and lower BLL in mean ages at sexual maturity (genitalia stage 5, pubic hair stage 5, or TV ≥ 20 mL) and duration of pubertal progression (onset to maturity), adjusting for potential confounders. Mediation analyses were conducted to quantify the percent of lead's effect attributable to its association with reduced somatic growth. ResultsAmong 481 evaluable boys, 28% had BLL ≥ 5 μg/dL. Adjusted mean ages at sexual maturity were 14.7 years for genitalia, 16.1 for pubic hair, and 13.9 for TV. In adjusted models, boys with BLLs ≥5 μg/dL had later maturity than those with lower levels by 4–5 months depending on pubertal indicator. In mediation analyses, height and body mass index at age 11 accounted for 40–71% of the shift in age at maturity for boys with higher compared to lower BLLs. Higher BLLs were not associated with pace of pubertal progression. ConclusionsHigher lead levels were associated with later attainment of sexual maturity in males, but not with the duration of pubertal progression. A high proportion of the delay in sexual maturity for boys with higher as compared to lower BLL was shown to be attributable to mediating effects of BLL on reduced growth.

Assessment of whole-sediment chronic toxicity using sub-lethal endpoints with Monocorophium insidiosum.

A whole-sediment test with the infaunal amphipod Monocorophium insidiosum has been developed to assess the long-term effects exerted by sediment contamination on survival, growth rates and attainment of sexual maturity. Juvenile amphipods were exposed for 28 days to a control sediment (native sediment) and three sediment samples collected in sites of the Venice Lagoon, characterized by contamination levels ranging from low to moderate, and absence of acute toxicity toward amphipods. Growth rate was estimated as daily length (μm d-1) and weight increments (μg d-1). The long-term exposure to the test sediments affected significantly both growth rate and attainment of sexual maturity of the females of M. insidiosum. In contrast, survival was high and uniform among all the samples, despite the contamination gradient. The results suggest growth to be the more reliable and statistically relevant endpoint. Attainment of sexual maturity, although allowed the identification of detrimental effects, was affected by a higher among-replicates variance as compared with growth rates, and thus less reliable than growth for the identification of impairments. The significant impairments observed both on growth and attainment of maturity evidenced the need to address the monitoring, also in the Lagoon of Venice, towards the assessment of the long-term effects on benthic species.

Changes in testicular size, echotexture, and arterial blood flow associated with the attainment of puberty in Dorper rams raised in a subtropical climate.

There is a paucity of information on the relationships of testicular morphology, echotextural attributes, and blood flow dynamics with pubertal development of rams raised in a subtropical climate. Forty-five Dorper rams (24 rams aged 8-11months and 21 rams aged 12-24months) were examined using a portable ultrasound scanner connected to a 7.5-MHz transducer. Computer-assisted analyses of testicular ultrasonograms utilized commercially available Image ProPlus® analytical software. Spectral Doppler scans of testicular arteries were performed immediately after scrotal (B-mode) ultrasonography to determine peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI=[PSV-EDV]/PSV), and pulsatility index (PI=[SPV-EDV]/mean velocity) of the blood vessels. The length of the testes (9.7±0.3 compared with 9.0±0.2cm) and scrotal circumference (33.3±0.5 compared with 31.8±0.4cm) were greater (p<0.05) but testicular depth (4.5±0.1 compared with 4.9±0.08 cm) was less (p<0.05) in sexually mature compared with peripubertal rams. [Corrections added on 9 Jan 2019 after initial online publication: The testicular size values in the sentence were corrected.] There were no differences (p>0.05) between the two age groups of Dorper rams in blood flow indices of testicular arteries. Mean numerical pixel values (100.5±4.1 compared with 89.2±4.8) and pixel heterogeneity (25.6±0.6 compared with 23.6±0.5) of testicular parenchyma were greater (p<0.05) in peripubertal than in postpubertal rams. Semen volume was negatively correlated with PI of testicular arteries (r=-0.57, p=0.04). In summary, the attainment of sexual maturity in the rams of the present study was associated with significant changes in testicular length and depth, scrotal circumference, and parenchymal echogenicity/hetrogeneity but not in testicular volume and blood perfusion rates. Testicular artery PI can be used to predict the volume of ejaculate in rams.

Effect of plane of nutrition on blood biochemical parameters and attainment of sexual maturity in growing yaks

Four divergent rations namely low protein-low energy (LP-LE), low protein-high energy (LP-HE), high proteinlow energy (HP-LE) and high protein-high energy (HP-HE) were formulated to supply two levels of digestible crude protein (DCP) (100 and 75%) and 2 levels of energy (TDN) (100 and 75%) for twenty four growing yaks (12 male and 12 female) of uniform age and body weights randomly divided into 4 groups of 6 animals (3 male and 3 female) in each. At random one dietary treatment was allotted to each group for a period of one year. At the end of feeding trial, average daily gain and feed conversion efficiency were highest in HE-HP group followed by HP-LE, LP-HE and LP-LE groups though their differences were statistically non-significant. The blood glucose level was highest in HP-HE group in comparison to the other groups; but the trends of plasma protein, albumin and urea levels were similar among the groups. The study also revealed that high protein-high energy ration is the suitable dietary combination for growing yak calves to support an average body weight gain of 371.8 g/day during 250 to 300 kg of body weight and could advance their sexual maturity.

Ontogeny of Surface Texture of Limb Bones in Modern Aquatic Birds and Applicability of Textural Ageing.

Despite its importance in various disciplines, a general method to assess ontogenetic ages of skeletal and fossil specimens has been lacking for birds. Although the textural ageing method was formulated to assess relative ontogenetic ages of specimens from inspection of bone surface textures, the exact correspondence of surface textures to ontogenetic stages has not yet been clear. In this study, bone surface textures of six major limb bones (humerus, ulna, carpometacarpus, femur, tibiotarsus, and tarsometatarsus) were described in postnatal ontogenies of four species of modern birds (Calonectris leucomelas, Phalacrocorax capillatus, Larus crassirostris, and Cerorhinca monocerata) from 14 to 28 individuals of known ontogenetic stages for each species. Consistently with the previous postulation, it was found that bones of chicks were characterized by rough surface textures with numerous grooves/depressions that host minute foramina. Bones of fledglings/juveniles, which are generally as large as those of adults but more slender, were characterized by the occasional presence of depressions and foramina. Histological observations confirmed that these rough surface textures were underlain by fibrolamellar bone tissue which is associated with active periosteal ossification. These results indicate that the smooth surface texture in adults is formed after the cessation of circumferential bone growth, which probably takes place between fledging and the attainment of sexual maturity. The available evidence suggests that the textural ageing is probably applicable to the entire Neognathae, a clade containing most crown-group birds. Anat Rec, 301:1026-1045, 2018. © 2017 Wiley Periodicals, Inc.

151 Associations of Testicular Size and Arterial Blood Flow with Sexual Development and Semen Characteristics in Dorper Rams Raised in a Subtropical Climate

Spectral Doppler (velocimetric) indices are important indicators of blood perfusion and physiological status of internal organs. Doppler ultrasound is used in andrology to assess the blood flow in the testicular arteries, aiding in the diagnosis of scrotal disorders and abnormal spermatogenesis. It was proposed that blood flow indices measured in the testicular artery, namely, blood flow resistance and pulsatility index, were significant predictors of semen quality in clinically healthy dogs. There is a paucity of studies on the associations of testicular morphology and blood flow dynamics with spermatogenesis in growing rams. Forty-five Dorper rams (24 rams aged 8 to 11 months and 21 rams aged 12 to 24 months) were examined using a portable ultrasound scanner connectecd to a linear-array 7.5-MHz transducer. Measurements of the testes were taken with built-in electronic calipers on images containing the largest cross-sectional area of each testicle in 3 planes (coronal, sagittal, and transverse). Colour and spectral Doppler scans were performed immediately after scrotal ultrasonography to detect the testicular arteries and record the following velocimetric indices: peak systolic velocity (PSV, cm/s), end-diastolic velocity (EDV, cm/s), resistive index (RI = [PSV – EDV)/PSV], and pulsatility index [PI = (SPV – EDV)/mean velocity] of the blood vessels. The length (9.7 ± 0.3 v. 9.0 ± 0.2 cm; mean ± SD) of the testes and scrotal circumference (33.3 ± 0.5 v. 31.8 ± 0.4 cm) were greater (P &lt; 0.05) in sexually mature rams than in peri-pubertal rams. There were no differences (P &gt; 0.05) between the 2 age groups of Dorper rams in mean values for blood flow indices measured in testicular arteries. Semen was collected by ejaculation into the artificial vagina from 38% (8/21) of post-pubertal rams and 21% (5/24) of peri-pubertal animals (Chi-squared test; P &lt; 0.05). Semen volume was negatively correlated with PI of the testicular arteries (r = –0.57, P = 0.04). In summary, the attainment of sexual maturity in Dorper rams maintained in a subtropical climate was associated with significant elongation of testes but not with the changes in testicular volume and blood perfusion. Testicular artery PI was a significant predictor of semen volume in peri-pubertal and sexually mature rams. Based on this and several previous studies, B-mode ultrasonography combined with echotextural analyses of the epididymides and accessory sex glands and serum testosterone measurements provide more useful information on the progression of sexual maturation and present semen quality in rams than the ultrasonographic assessment of testicular dimensions and an array of blood flow indices.