Mohamed Hammadi

Role of the somatotropic axis in the mammalian metabolism

The metabolism in mammalian is regulated by multiple levels of hormone action, with complex feedback and control mechanisms. The somatotropic axis, essentially consisting of growth hormone (GH), insulin-like growth factors (IGF-I and -II), their associated carrier proteins, and receptors, plays a key role in the control of the regulation of metabolism and physiological process. Among this axis, other hormones like insulin, leptine, glucocorticoids or thyroid hormones are involved in this mechanism by modulating GH and/or IGF-I synthesis and availability. This review summarizes the complexity of the regulation of the metabolism by the somatotropic axis using different examples such as special nutritional situations or growth promoters administration.

A survey of chemical and nutritional characteristics of halophytes plants used by camels in Southern Tunisia

The camel (Camelus dromedarius) is well adapted to the utilization of vegetation of low nutritional value in its natural habitat zone, thanks to its aptitude to vary food and to search plants that are rich in water content and that can make up for its nutritional deficits, particularly as concerns mineral elements. Therefore, a survey was carried out to determine camels pasture quality, dietary preference and to characterize the chemical characteristics and nutritional value of different halophytes plants in a region of Southern Tunisia during spring season. Laboratory analysis were conducted on fourteen vegetable species appertained to seven different botanical families: Chenopodiaceae, Graminaceae, Tamaricaceae, Zygophyllaceae, Asteraceae, Frankeniaceae and Plumbaginaceae. Data obtained indicate an high variability of nutritional content of halophytes plants preferred by camels, specially for dry matter, crude protein, fiber fractions, ash and mineral elements.

Nutritional composition of three fodder species browsed by camels (Camelus dromedarius) on arid area of Tunisia.

Browsing camels have access to different plant species in relation to the kind of pasture they can reach. A study was conducted in an arid region of Southern Tunisia to determine the dietary preference and forage quality of free ranging camels. Foliage consisting of leaves from Limonium pruinosum, Retama raetam and Stipa tenacissima, was collected during the dry season to evaluate the chemical characteristics and nutritional value of these browse fodder species. The dietary preference was studied using 15 adult camels which were selected from a herd of 50 animals appropriately marked for identification. There was a significant difference in the chemical composition and nutritional value of plant species collected. Based on crude protein (CP) content and nutritional value, the three fodder species browsed can be recommended as good-quality food source for camels under pastoral management.

Effect of α-Amylase, Papain, and Spermfluid® treatments on viscosity and semen parameters of dromedary camel ejaculates

Ejaculates from five clinically healthy dromedary camels (Camelus dromedarius) were used to evaluate the effects of different enzymatic treatments (Amylase, Papain, Spermfluid) on liquefaction and seminal parameters. After collection, ejaculates were divided into 5 aliquots: (1) kept undiluted (control); or diluted 1:1 with: (2) Tris-Citrate-Fructose (TCF), (3) TCF containing Amylase, (4) TCF containing Papain or (5) Spermfluid containing Bromelain. At 120 min after dilution, each aliquot was evaluated, at 20-min intervals, for viscosity, motility, viability and agglutination. Only the aliquots diluted with TCF containing Papain underwent complete liquefaction. Sperm motility decreased significantly during the observation times, except for the samples diluted with Spermfluid (P=0.005). Diluted samples showed different levels of agglutination, with the lowest being observed in the control and the highest in the Papain-treated samples. The viscosity of dromedary camel ejaculates could be effectively reduced by using the proteolytic enzyme Papain.

Effects of vacuum level and pulsation rate on milk ejection and milk flow traits in Tunisian dairy camels (Camelus dromedarius)

This work aims to compare the effects of milking at two vacuum levels (38 and 48xa0kPa) and three pulsation rates (60, 90, and 120xa0cpm) on milk production and milk flow characteristics. Six multiparous Maghrebi camels in late lactation and once daily milked were used. The best combination of setting for camel’s milking was high vacuum and low pulsation rate (48xa0kPa/60xa0cpm). Milk yield and average and peak milk flow rate were the highest, while milking time was the shortest using this combination of setting (3.05u2009±u20090.30xa0kg, 1.52u2009±u20090.21xa0kg/min, 2.52u2009±u20090.21xa0kg/min, and 3.32u2009±u20090.31xa0min, respectively). Lower vacuum level lengthened milking time by more than 100xa0% and was not sufficient to extract milk correctly (1.69 to 2.48 times less milk yield harvested), suggesting a negative interaction with the stimulatory effect of pulsation. Higher pulsation rates did not better stimulate the camels and induced more bimodality and lower milk flow rates. Animal characteristics and liner/claw design affect machine milking and further investigations must be carried out to verify their effects and to study long-term effect of high vacuum level on udder health and teat condition.

Effects of a GnRH administration on testosterone profile, libido and semen parameters of dromedary camel bulls.

GnRH treatment has been suggested to increase testosterone levels temporarily and to stimulate libido in stallions, but its use has not fully ascertained in dromedary camels. The aim of this work was to study the effects of administering 100 μg of GnRH on testosterone profile, libido and semen parameters in dromedary camels. The same bulls were used as self-controls and experimental group. Blood samples were collected every 20 min (T0-T12) for 4h, and semen collections were performed over a 2-hour period after T12. GnRH was administered immediately after T0. In GnRH-treated bulls, testosterone levels showed an upward trend, peaking after 140 min, and then slowly decreasing. GnRH administration also led to a decrease in mating time and an increase in spermatozoa concentration. Overall, it seems that administration of 100 μg GnRH might increase testosterone levels temporarily and enhance camel reproduction performance.

Effect of changes in milking routine on milking related behaviour and milk removal in Tunisian dairy dromedary camels

We studied the effects of changes in the milking routine (lack or presence of 30-s prestimulation, 0 or 1, 2 or 4-min delay between preparation and cluster attachment) and environmental perturbation (unusual loud sounds capable of frightening animals just after stall entry or during the course of milking) on milk removal and milking-related behaviour in dairy dromedary camels. A 30-s prestimulation decreased incidence of bimodal milk flow curves and increased occurrence of the best milk ejection patterns with higher milk flow but had limited effect on milk production in our well-trained animals within a good machine milking setting. However, unusual sounds heard from the beginning of milking or even after milk ejection caused inhibition or disruption of milk removal and modification of camels behaviour. Milk ejection was significantly delayed (1·58±0·17xa0min), residual milk increased over 40% of total milk yield and average and peak milk flow rates were significantly lowered when unusual noises were heard from the beginning of milking. These environmental perturbations increased signs of vigilance and the number of attempts to escape the milking parlour. Delaying cluster attachment for over 1xa0min after the end of udder preparation caused serious milk losses. Up to 62% of total milk was withheld in the udder when the delay reached 4xa0min. Average and peak milk flow rates also decreased significantly with delayed milking. Signs of vigilance and attempts to escape from the milking parlour appeared when camels waited for over 2xa0min. After a 4-min delay, camels showed signs of acute stress. Defaecation prior to milk ejection (solid faeces) and rumination during milking can be used to assess camels milk ejection during milking. Animal welfare and milking efficiency can be ensured when camels are pre-stimulated, milked in calm conditions and with cluster attachment within a maximum of a 1-min delay after stimulation.

Antimicrobial resistance and molecular characterization of virulence genes, phylogenetic groups of Escherichia coli isolated from diarrheic and healthy camel-calves in Tunisia

This study was conducted to determine the prevalence of virulence genes, serogroups, antimicrobial resistance and phylogenetic groups of Escherichia coli strains isolated from diarrheic and healthy camel calves in Tunisia. From 120 fecal samples (62 healthy and 58 diarrheic camel calves aged less than 3 months), 70 E. coli isolates (53 from diarrheic herds and 17 from healthy herds) were examined by PCR for detection of the virulence genes associated with pathogenic E. coli in animals. A significantly greater frequency of the f17 gene was observed in individual camels and in herds with diarrhea, this gene being found in 44.7% and 41.5% of isolates from camels and herds with diarrhea versus 22.5% and 11.7% in camels (p=0.05) and herds without diarrhea (p=0.02). The aida, cnf1/2, f18, stx2 and paa genes were found only in isolates from camels with diarrhea, although at a low prevalence, 1.8%, 3.7%, 1.8%, 3.7% and 11.3%, respectively. Prevalence of afa8, cdtB, eae, east1, iroN, iss, kpsMTII, paa, sfa, tsh and papC genes did not differ significantly between herds with or without diarrhea. Genes coding for faeG, fanC, f41, estI, estII, CS31a and eltA were not detected in any isolates. All isolates were sensitive to amikacin, chloramphenicol, ciprofloxacin, gentamicin and ceftiofur and the highest frequency of resistance was observed to tetracycline, and ampicillin (52.8% and 37.1% respectively). The phylogenetic groups were identified by conventional triplex PCR. Results showed that E. coli strains segregated mainly in phylogenetic group B1, 52.8% in diarrheic herds and 52.9% in healthy herds.

Relationship between external and internal udder and teat measurements of machine milked dromedary camels.

This study aims to determine the relationship between internal and external udder and teat measurements and evaluate their correlation with milk yield and milk partitioning in the udder of dromedary camels. Six Maghrebi camels reared under intensive conditions were monitored at early, middle, and late lactation. Udder measurements included udder depth, udder horizontal circumference, fore and rear teat length and diameter. Besides, scans of the left fore and rear quarters were taken in duplicate before morning milking (16xa0h) using an oxytocin receptor blocking agent (Atosiban) to determine teat and gland distension before milk ejection. Cisternal and alveolar milk volumes were then evaluated. Correlation coefficients were calculated between the performed udder external and ultrasonographical measurements and cisternal and daily milk production on the measurement day. Significant effect of lactation stage was observed in all measured traits. All internal and external measurements decreased significantly at late lactation as well as cisternal and total milk yield. The quarter cisternal area averaged 16.3u2009±u20092.2xa0cm2 and decreased about three times at late lactation compared to early and middle lactation. All external and internal measurements were positively and highly correlated (Pu2009<u20090.001). The knowledge of the relationship between udder internal and external morphological traits would permit to predict udder cisternal storage capacity and can ultimately be adopted to improve milk storage capacity of dromedary camels.

Effect of continuous female exposure on behavioral repertoire and stereotypical behaviors in restrained male dromedary camels during the onset of the breeding season.

This study aimed to test the effects of the three management systems on the behavioral repertoire and particularly on the incidence of stereotypical behavior in restrained camels. Five male camels were tested under the following management systems: (i) unexposed, housing in a single box (Unexpo); (ii) continuous exposure, exposed continuously to females (ConExpoF); and (iii) re-unexposed, housing again in a single box (Re-Unexpo). Every day, bulls were filmed for 30xa0min and videos were analyzed using a focal animal sampling ethogram. Under the ConExpoF system, camels spent the majority of time in standing with opened legs (490.0u2009±u200994.3xa0s), looking (925.0u2009±u200993.7xa0s), and walking toward the females (206.0u2009±u200973.4xa0s) and they ate and ruminated less compared to Unexpo and Re-Unexpo systems. Rumination and standing durations were significantly longer in Re-Unexpo than in Unexpo and ConExpoF management systems. When camels were continuously exposed to females, they showed few stereotypical behaviors compared to Unexpo (490.0u2009±u2009146.1xa0s) and Re-Unexpo (624.0u2009±u2009146.1xa0s) systems. The frequency of both total and oral stereotypes was significantly higher in Unexpo and Re-Unexpo systems compared to ConExpoF; however, no significant difference was observed among the three management systems in the frequency of locomotor stereotypes. Overall, it appears that the continuous female exposure system might be a suitable management practice for male camels used for intensive reproduction, as it decreases the manifestation of stereotypical behavior in comparison with housing for 24xa0h in a single box.