Avi Rosenstrauch

Growth rate, total body water volume, dry-matter intake and water consumption of domesticated ostriches ( Struthio camelus )

Growth rate, total body water volume (TBW), dry-matter intake (DMI) and water consumption were determined in ostriches from hatching to 350 days at which time they weighed approximately 100 kg. A Gompertz equation was used to describe the sigmoidal growth curve; mature body mass (Mmb) wascalculated as 104·1 kg from this equation. Highest average daily gain (ADG) was 455 g/day which occurred between 70 days and 98 days. Time to reach 0·5 Mmb and to grow from 0·25 to 0·75 Mmb per Mmb025 were 46·8 days and 39·7 days, respectively. Maintenance energy requirements were 1·07 MJ/kg063per day and energy requirements for kg mb increase were 0·260 MJ/kg109: thes e values were derived from a non-linear regression model. TBW as a fraction of mb declined from 0·84 in 35-day-old chicks to 0·57 in 322-day-old birds, indicating a concomitant increase in the fraction of body lipid content. Mass specific DMI decreased from 0·061 g/g mb in chicks to 0·020 g/g mb in 322 to 350 day old birds, while mass specific water influx decreased from 0·21 ml/g mb to 0·046 ml/g mb during this time. The ratio of DMI to ADG increased steadily from 1·07 to 17·1; the ratio of water consumption to DMI remained relatively constant at approximately 2·3.

Time-activity budget of ostriches (Struthio camelus) offered concentrate feed and maintained in outdoor pens

The time-activity budget of 5–6-month-old growing ostriches (mean body mass = 57.4±14.5 kg; n = 8) that were offered only concentrate feed and were maintained on packed ground in four outdoor pens (3×6 m each) was studied. They were kept in pairs matched for age and weight. The ostriches were active for ∼ 12 h during the day and sat for 12 h at night. They spent 20.4±14.0% of the 12-h active day sitting, 61.5±12.5% walking, 5.5±3.2% standing, 6.6±3.6% eating concentrate feed, 5.0±1.7% foraging (pecking the ground) and 1.1±0.4% drinking. Each pair of ostriches usually behaved in synchrony, i.e., ate together, drank together, etc. Sitting was mostly done with their necks straight up and their legs folded under their bodies, and on occasion with their necks and heads prone on the ground. The ostriches spent most of their time walking with their necks straight up and sometimes with their heads in an S-shape more or less parallel or close to the ground. They usually walked at a rate of ∼ 1 m/s−1 along the edges of their pens. Each ostrich consumed 1911±266 g dry matter (DM) feed day−1; this figure was based on the intake of each pair of birds. They spent 46.4±25.3 min eating this feed and pecked at their feed 2830±394 times; therefore they consumed 41.2±5.7 g DM min−1 feeding and 0.7±0.1 g DM per peck. They also consumed 129.2±25.4 g DM earth, spent 35.3±13.3 min day−1 foraging and pecked at the ground 1957±737 times day−1; therefore they consumed 3.7±1.4 g DM earth min−1 foraging and 0.1±0.0 g DM per peck. Total water influx, which was determined using tritiated water, was 10.1±3.4 l day−1. Furthermore, it was estimated that 1.0±0.1 l day−1 were obtained from preformed and metabolic water from feed and 9.1±3.1 l day−1 from drinking. They spent 8.2±3.3 min day−1 drinking, during which time they took 315±106 sips.

Leydig cell differentiation during the reproductive cycle of the seasonal breeder Camelus dromedarius: an ultrastructural analysis.

Spermatogenesis and Leydig cell development in the dromedary were analyzed at the ultrastructural level and correlated with fluctuations of testosterone synthesis during the mating and nonmating seasons. It was found that (1) spermatogenesis and diameter of the seminiferous tubules are dissociated from seasonal fluctuations of testosterone synthesis as they remain similar throughout the year; (2) the volume of the interstitial tissue and the rate of testosterone synthesis are correlated since both increase during the mating season and both diminish during the nonmating season; (3) during the mating season, reduction of the tubular smooth endoplasmic reticulum (SER) and proliferation of condensed SER correspond to the relatively high rate of testosterone synthesis by the 4-ene pathway; (4) during the mating season there is a drastic reduction of the SER and proliferation of myelin figures within the Leydig cells which disrupt at the end of their differentiation. During the nonmating season, testosterone synthesis is probably impaired only at the final stage of differentiation of the Leydig cell.

Testicular steroidogenesis in the camel (Camelus dromedarius) during the mating and the nonmating seasons

Enzyme reactions in the camel testis involved in androgen synthesis were studied to determine the factors which account for the low testosterone production during the non-mating season (NMS). Testes excised during the NMS were found to have a relatively high activity of the 3 beta-hydroxysteroid dehydrogenase systems of pregnenolone, 17 alpha-hydroxypregnenolone, and dehydroepiandrosterone, but the 4-ene-17 alpha-hydroxylase and 4-ene-17,20-lyase systems were apparently less active than the 5-ene-17 alpha-hydroxylase and 5-ene-17,20-lyase. On the other hand, testes excised during the mating season (MS) were found to have a relatively high activity of 4-ene-17 alpha-hydroxylase, 4-ene-lyase, and 17 beta-hydroxysteroid oxidoreductase. The 19-hydroxylation and aromatizing activities for testosterone and androstenedione were not detected in testes excised in either season. It is proposed that during the NMS the predominant route of testosterone biosynthesis is pregnenolone leads to 17 alpha-hydroxypregnenolone leads to dehydroepiandrosterone leads to androst-5-en-3 beta, 17 beta-diol leads to testosterone.

Reproductive cycle of free-living male Saharan sand vipers, Cerastes vipera (Viperidae) in the Negev desert, Israel.

The Saharan sand viper, Cerastes vipera (Linnaeus, 1758), is distributed in all Saharan countries, being confined to sand and dune systems. This relatively small snake, up to 35 cm, is nocturnal, is active from spring to autumn (April to October) and hibernates during the winter (November to March). We predicted that C. vipera would have peak plasma testosterone concentration at mating and that the vas deferens would contain abundant spermatozoa at that time. To test our predictions, we collected information on the time of mating and measured monthly testosterone concentration, testes size and testicular activity in free-living male C. vipera during its active period from April to October. Mating occurred only during spring. The pattern of plasma testosterone concentration, testes volume, seminiferous tubule diameter and spermatogenesis all followed the general pattern of high values in autumn and spring and low values in early summer. Our predictions were partially supported. There was a high plasma testosterone concentration at mating in spring and the vas deferens contained abundant spermatozoa, as predicted, but there was also a high plasma testosterone concentration in autumn without mating. We concluded that: (1) males are both aestival in that they produce spermatozoa in autumn, which they store over the winter hibernation period, and vernal in that they produce spermatozoa in spring prior to mating; (2) matings are associated with spermatogenesis; and (3) the high plasma testosterone concentration is concomitant with both matings and spermatogenesis in spring and with spermatogenesis in autumn. We propose that C. vipera has a single peak of testicular activity and plasma testosterone concentration which start in autumn and end in spring. We also propose that spermatogenesis is prior to spring mating and, consequently, is prenuptial.

Effect of restricted cooled drinking water on the performance of broiler breeder hens in a hot, dry climate

Abstract 1. We tested the effect of cooled drinking water on the performance of broiler breeder hens maintained in a hot, dry climate. Hens from 24 weeks of age (mean body mass = 2.5 kg) were offered one of three treatments: cooled water (18.5°C, COLD) or tap water (27.5°C, CONR) twice a day for a total time of 2–5 h, or tap water ad libitum (CONA). Food was restricted for all hens. 2. Daily water influx in the COLD hens (120 ml/kg) was similar to that of the CONR hens (123 ml/kg), but was 36% lower than that of the CONA hens (163 ml/kg). The same pattern was found in the ratio of water drunk (ml/d) to food intake (g/d): 1.85 and 1.88 in the COLD and CONR hens, respectively, and 2.73 in the CONA hens. 3. There were no significant differences in body mass change among groups. Over the first 28 d of treatment, the COLD hens increased their body mass by 20.9 g/d, the CONR hens by 19.6 g/d and the CONA hens by 21.8 g/d. 4. When offered cooled water from 24 to 30 weeks, egg production decreased in the COLD hen...