Effect of season and age on main characteristics of sperm production in the Ouled-Djellal rams

A R Benia¹, M A Saadi^2,3, A Ait-Amrane¹, T B Belhamiti¹, S M A Selles¹ and R Kaidi^2,3

¹ Institute of Veterinary Sciences, Ibn Khaldoun University, BP 78, 14000, Tiaret, Algeria.
arbveto@yahoo.fr
² Institute of Veterinary Sciences, Saad Dahlab University, BP P 78 Zaâroura 14000, Tiaret, Algeria.9000, Blida, Algeria
³ Biotechnology and Animal Reproduction Laboratory Saad Dahlab University, 9000, Blida, Algeria.

Abstract

This study focused on determining the effect of season and age on 4 main parameters of sperm production in rams (youngs and adults) of the Ouled-Djellal breed. It was conducted in the saharian region of Ouled-Djellal (Biskra, Algeria). The aim of this study was to evaluate the characteristics of the sperm of the two age groups of rams and to define the variations and interactions between the 4 parameters studied during each season. Volume, mass motility, concentration and the possible number of sperm straws (400 million total sperm cells) were studied during one year in 10 rams (5 youngs about 18 months old and 5 adults) with a good body condition score. Using an artificial vagina, ejaculates were obtained once a week per ram with 2 ejaculations per session (52 samples per ram).

The volume of ejaculate (1.23 ± 0.31 ml) was highly influenced (P <0.0001) by the season but not by the age (P <0.84). It was more important in spring and autumn than in winter and summer. The mass motility did not show seasonal variation (P <0.19), but showed significant variation between age groups (P <0.0001) : 4.42 ± 0.14 for adults, and 3.80 ± 0.21 for youngs. The sperm concentration was not influenced by the season (P <0.098), but it varied significantly with the age category (P <0.036): 4.25 ± 0.19 (adults) and 4.01 ± 0.27 spermatozoa × 10 ⁹ / ml (youngs). The number of straws per ram was not significantly influenced by seasonal factors (P <0.075) and age (P <0.089) : 12.4 ± 1.5 per week.

Keywords: adult, artificial insemination, concentration, motility, reproduction, spermogram, straw, volume, young

Introduction

Stock-rearing in Algeria mainly concerns sheep, goats, cattle and camel, in which sheep predominate with 80% of the total (Nedjraoui 2006), dominated by the race of Ouled-Djellal (61%) (Dehimi 2005). Nearly one third of this herd are males (MiADR 2015).

This breeding represents a tradition, and constitutes the unique income of one third of the Algerian population. The economic importance of this breeding represents an appreciable source of animal proteins (meat and milk) as well as a significant contribution of animal by-products (skin and wool), in particular in semi-arid zones (Abbas et al 2002, Kanoun et Kanoun 2004).

For this purpose, it is essential to find ways to improve sheep productivity in Algeria. This improvement is associated with the control of reproduction which is the center piece of the economic efficiency of any breeding program (Nedjraoui 2006). For successful productivity of sheep, herds must pass through the control of ram’s reproduction (Ólafur and Jón Viðar 2011).

Despite the male's share in reproduction, only a few investigations have been carried out so far in Algeria to study the spermatic characteristics of the Ouled-Djellal breed (Aissaoui et al 2004, Ghozlane et al 2005). On the other hand, there are no data on the exploitation of young rams of this breed in the various techniques of artificial insemination or natural mounting.

Reproductive biotechnology offers considerable opportunities for livestock production. It involves in particular the application of new reproductive technologies such as control of sexual activities, artificial insemination, embryo transfer, production and freezing of semen.

The analysis of sperm production is of great importance because it is significantly correlated with sexual activity.

Artificial insemination, which facilitates the organization of breeding and allows the spread of breeding males, is the cornerstone of any breeding program. Due to the particular constraints inherent to the ovine species (insemination with fresh seed), this technique is not as well developed as for the bovine species.

There are, however, a number of prerequisites for successful use of AI; its success is a characteristic dependent on the two individuals of the couple. It is only possible if the male produces and ejaculates a fertilizing sperm and if the female ovulates at the right time a viable oocyte and possesses a genital tract compatible with the survival of the spermatozoa. The success of artificial insemination can be considered to be correlated with the genetic and environmental factors of male and female as well as sex related environmental factors such as year or season and age.

The production of sperm is a tool which takes place in the current practices of sheep breeding, because with artificial insemination, they tend to improve the genotypes of animal species as well as the preservation of the genetic heritage. Comprehensive control of reproduction in a breeding operation requires knowledge and control of breeders. Accordingly, the genetic value of the rams used is primordial.

The objective of this study is to contribute to the increase of productivity of livestock farming by characterizing and improving the reproductive capacity of rams by:

• The assessment of the influence of some environmental factors on the production of semen in rams. These improvements can be considered in the short term by better management of some factors of environmental variation; however, in the longer term, by setting up a selection of these characteristics.
  
  
• Determining the variations in the quantitative and qualitative characteristics of sexual activity according to age and the different seasons of the year.
  
  
• The determination of the right moment for the best breeding season for the rams of the Ouled-Djellal breed.

To meet these objectives, we have mobilized the data routinely collected by the CNIAAG as well as the performance monitoring by the following analysis: the sperm parameters (volume, concentration, mass motility and the possible number of straws) in order to increase the number of insemination doses a ram can produce daily without impairing its fertility, which can be obtained by modifying the processes of making doses (increasing sperm dilution, decreasing dose volume) and / or increasing the amount of usable sperm produced by a ram.

Material and methods

Choice of the region

The experiment was conducted at the “Experimental Station of the Regional Center of Artificial Insemination and Genetic Improvement” in the region of Ouled-Djellal of the Aurès massif, about 100 km south-west of the town of Biskra (Algeria), located in a purely pastoral Saharian region. (Geographic coordinates: longitude 5° 3′ 51″ East, latitude 34° 25′ 44″ North, altitude 196 meters above sea level).

It is characterized by an arid desert climate, hot and dry in summer (temperature between 35 and 45 ° C on day, and between 25 and 35 ° C at night), cold and dry in winter (temperature between 10 and 20 ° C on day, and between -2 and 5 ° C at night).

Choice of the breed

The target population is the white Arabian breed (Ouled-Djellal), which became an "A.O.C." (appellation d'origine controlée = controlled name of origin). This sheep is not only beautiful and strong but it adapts to imposed living conditions. Its meat is a delicious sheep meat. It is an interesting breed based on its physical, productive and reproductive abilities.

Choice of the rams

Ten (10) Ouled-Djellal rams aged between 18 months and 4 years were selected for our experiment. These rams were divided into two groups. The first consisted of 5 young rams aged about 18 months and the second, 5 rams adults aged between 3 and 4 years. These males had been in contact with the ewes only during the time of the sexual activity test.

To make management decisions regarding the choice of the ram the "Body Condition Scoring" was used. The BCS was ranging from 3,0 to 3,5 for the selected rams.

Experimental design

Prophylactic treatments were recommended, and only healthy subjects were selected. Each ram was identified and medically examined with emphasis on the integrity of the genital area.

These animals belonged to a semi ranching, in addition to grazing on natural woody plants. They received a nutritional complement of barley, corn and soybeans (800 g/day); they had free access to water and mineral lick-blocks containing oligo-elements.

Collection of sperm

The sperm was collected at the rate of two ejaculations once a week during one year (52 sperm samples per male) using an artificial vagina (AV) and a ewe (in heat or not) used as a teaser. The collection was done manually, as the ram mounted the teaser; the penis was grasped by the operator and directed into the AV.

Semen quality assessment

Immediately after collection, the semen volume was determined by direct reading of the graduations of the collection tubes. The reading occurred without taking into account the foamy part of the ejaculate.

Mass motility was scored from 0 to 5 (0: motionless; 1: individualized movement; 2 very slow motion; 3: low amplitude motion; 4: fast motion, no swirl; 5: fast movement with swirl).

Using a sterile pipette, a drop of semen was placed on a slide on the hot-stage of the microscope equipped with a heating plate set at 39 °C (Winix photon microscope, objective 10, magnification × 40). Then the mass motility of the spermatozoa was observed (Druart et al 2009).

The concentration, expressed as the number of spermatozoa per volume unit, was determined with a photometer BXB 840 NO140 IMV pre-calibrated for ram sperm. The concentration was measured by mixing 10 μl of fresh sperm and 3.99 ml of formol-physiological saline (9 g NaCl / 1000). Using a spectrophotometer we evaluated:

• the average concentration per ejaculate that varies between 3 and 6 billion spermatozoa;
  
  
• the volume of the diluent to be added (Laiciphos);
  
  
• the number of doses (number of flakes or straws of 0.25 ml) to be prepared at the rate of 400 million total sperm cells per straw (fresh seed, as here), or 200 million total sperm cells per straw (in the case of frozen produce).

So, the number of doses was: (mean volume x mean concentration) / 400 000 000.

The percent of living sperm cells and their anomalies were not studied here.

Statistical analysis

The results were expressed as mean and standard deviation. The comparison of the means of the different batches and at different seasons was done using the Student's test.

In order to verify the effectiveness of the rams studied and the comparison between the categories and the four seasons, analyzes were made using the procedure described by Systat vers. 7, Past to 1.91.

In the case where this variable distribution was not normal, we used the global linear model (GLM).

The correlations between the different parameters and their dilutions over time are shown by a principal component analysis (PCA) using the Past software to 1.91. In this type of test, the different seasons and their parameters have coordinates between -1 and +1 and belong to a correlation circle. The interpretation of the ACP was done from the examination of the circle of correlations and the position of the status of the variables on the factorial axes.

From the coordinates of the variables and factors in the first three axes of the principal component analysis, a hierarchical ascending classification was carried out in order to detect the correlated groups from the calculated similarity measurements through euclidean distances between the coordinates of the quantitative variables studied.

Results

Effect of the age

The sperm collected had a viscous and whitish appearance. The mean ejaculate volume was 1.18 ± 0.39 ml in young rams compared to 1.29 ± 0.23 ml in adult rams; the overall mean was 1.23 ± 0.31 ml (Table 1).

The mass motility values obtained were respectively 3.80 ± 0.21 and 4.42 ± 0.14 for young rams and adult rams. The overall average was 4.11 ± 0.08 (Table 1).

The average concentration of ejaculate during the experiment was 4.01 ± 0.27 spermatozoa.10⁹ / ml in young rams and 4.25 ± 0.19 spermatozoa. 10⁹ / ml in adults. The total mean was 4.13 ± 0.23 spermatozoa.10⁹ / ml (Table 1).

The general mean of the number of straws obtained by collection in all the rams was 12.4 ± 1.5; it was 11.8 ± 1.0 in the young and 13.7 ± 2.2 in the adults (Table 1).

The statistical analysis of the results obtained during this experiment does not indicate any statistically detectable effect of the influence of age on the parameters of the volume and the number of straws. On the other hand, we noted significant differences between the two classes of the age for the mass motility variables (P <0.0001) and the seminal concentration (P <0.036) (Figure 1).

Figure 1. Variations in sperm parmeters according to the rams age categories

Effect of the season

The analysis of the variance indicates that the season factor had a highly significant influence on the volume parameter (P <0.001) (Table 2). The statistical treatment of the results, reported in this table, shows no significant difference for the other three parameters (mass motility, concentration, and number of straws by collection) during the different seasons of the year of our experiment.

In the rams of Ouled-Djellal breed, the overall seasonal variations in volume, concentration and number of straws showed maximum values recorded in autumn and spring and lower values in winter and summer. The extrapolation of the mean seasonal motility scores obtained during the study period revealed a nearly similar pattern throughout the year, with the exception of the spring season as we recorded extremely high values concerning all the rams (Figure 2).

Figure 2. Effect of season on fresh seed parameters of all rams

Effect of the two factors (season and age category) on spermatic parameters

We have interpreted all our results by a PCA (Principal Component Analysis) (Figure 3). The ascending hierarchical classification is represented by:

• The first group (group 1) represented mainly by the winter and summer seasons. This group is negatively correlated with the age factor of the ram. It is characterized by a low seasonal activity,
  
  
• The second group (group 2) represented by autumn and spring; this group correlates positively with the season factor; we noted a strong seasonal activity (Figure 4).

Figure 3. Seasonal Principal Component Analysis (PCA) of the various parameters studied. win :winter, sum :summer, au :automn, sp :spring, jne: youngs, adt: adults, C: concentration, NF: number of straws, M: motility, Vo: volume.

Figure 4. Ascending hierarchical classification of different seasons. Sum: Summer, Win: Winter, Spr: Spring, Aut: Automn

Correlation between sperm parameters

Correlation between sperm parameters in adult rams

Table 3 shows a significant correlation between sperm concentration and the number of straws in adult rams (r = 0.96) and (P <0.0356). Thus, the volume of ejaculate correlated significantly with the values of the number of straws (r = 0.96 and P <0.0440).

Correlation between sperm parameters in young rams

The statistical analysis showed a significant correlation between the concentration of fresh seed and the number of straws from young rams (r = 0.98 and P <0.0245) (Table 4).

Discussion

Spermatic volume

The average volume of sperm per ejaculate in rams of the Ouled-Djellal breed was 1.23 ± 0.31 which also supports the results of Hafez and Hafez (2000), where they found 0.5-2 ml of semen/ejaculate in ovine rams. This average volume is also comparable to that collected in rams by Lacaune and Manech in two centers of artificial insemination in France (David et al 2007). On the other hand, it is higher than that collected by electro-ejaculator in tropical rams of the same age group (Rege et al 2000: 0.24-0.60 ml of semen/ejaculate).

In agreement with various authors (Mandiki et al 1998, Kumar et al 2010), we found that age had no significant effect on ejaculate volume. This may be related to the method of collection (Tabbaa et al 2006) and our small number of animals. Our results shows that average sperm volumes are slightly higher in adult rams than in young rams. The average volume of the ejaculate would therefore increase according to body growth. This is consistent with observations in several tropical (Mohamed and Abdelatif 2010) or subtropical breeds (Salhab et al 2003; Kishk 2008).

Table 2 shows that the volume of the ejaculate was greater in autumn and spring (photoperiod effect and good food availability) than in winter and summer, and that the seasonal variation was highly significant (P <0.001). An identical evolution was reported in rams of the same breed (Ghozlane et al 2005). The same findings were also mentioned by Karagiannidis et al (2000) on rams of Chios and Friesian breeds and Kafi et al (2004) for rams of the Karakul breed in Iran.

Contrary to the results of Rege et al (2000), Zamiri and Heidari (2006) and David et al (2007), who reported correlations between volume, concentration and sperm count produced, we did not find any correlation between the volume and these sperm parameter, which agrees with the results of Goerke et al (1970).

Mass motility

The average value of the mass motility obtained (4.11 ± 0.08) is very acceptable (Table 1) compared to the value 4, from which this parameter is considered very good (Baril et al 1993). The sperm in this case is very suitable for artificial insemination. The mean score of mass motility in rams of the present study is higher than the score reported by Ghozlane et al (2005) in rams of the same breed (average age of 4 years) and the score of Barbary sheep (Ammotragus lervia) in the Mediterranean area (1.88 ± 1.4) by Pérez-Garnelo et al (2005).

On the other hand, it comes closer to the score estimated by Aissaoui et al (2004), in a four-month study (March-June) concerning rams of the same breed aged between 3 and 5 years. It is lower than the scores reported by David et al (2007) in rams over 18 months of age (4.64 ± 0.12 and 4.60 ± 0.30 respectively in two artificial insemination centers in France).

The mass movements of spermatozoa of adult rams were significantly higher than those of youngs with a highly significant difference. The determination of this parameter constitutes, at the present state of knowledge, a criterion to select the ejaculates to be inseminated and of breeding animals.

Because it reflects a percentage of live and mobile spermatozoa, so the number 4 corresponds to 70 to 80% of mobile spermatozoa (Baril et al 1993). In agreement with the results of Rege et al (2000), Kridli et al (2006) and contrary to those of Kumar et al (2007), mass motility is accentuated with advancing age, which explains the difference between mass motilities recorded in older rams belonging to the same breed or different breeds.

In agreement with Ghozlane et al (2005) and contrary to the results of several studies carried out in Mediterranean or tropical environments on sheep or goats (Karagiannidis et al 2000, Delgadillo et al 2001, David et al 2007, Zarazaga et al 2009) the evolution of the mass motility in this study does not undergo significant variation between the different seasons. Concerning the effect of the photoperiod on the mass motility, the results obtained are also contradictory with those obtained in ovine animals reared under very different conditions than ours (Rege et al 2000, Yamaki et al 2003, Kafi et al 2004, Issa et al 2001, Kumsa et al 2006).

Concentration

The mean value of the overall sperm concentration / ml of ejaculate (4.13 ± 0.23) (Table 1) was in the standards related to ovine breed, whose are between 2.00 and 6.00. It is very different that the average recorded by Hassan et al (2009) in the local breed of Bangladesh (1.03 ± 0.61 x 10 ⁹ spermatozoa / ml).

In our experiment, the values of sperm concentration in young rams were significantly lower than those in older rams. The same observation was made by Aissaoui et al (2004) and Ghozlane et al (2005). This difference due to the difference in age was highlighted by several studies that emphasized a strong positive correlation between age and concentration (Rege et al 2000, Okukpe et al 2001, Salhab et al 2003, Recabarren et al 2008, Hassan et al 2009). On the other hand, this relationship has not been observed by other authors (Issa et al 2001, Tabbaa et al 2006, Kumar et al 2007). Contrary to the idea reported by David et al (2007), the effect of age on the concentration is not necessarily accompanied by the effect of age on the volume.

The low concentration in this study during the winters and summer seasons may be related not only to the collection frequency, but also to environmental factors (vegetation, climate) (Kumar et al 2010). In addition to age, the diet significantly influences the sperm concentration / ml (Dana et al 2000, Fourie et al 2004, Kheradmand et al 2006, Ahmed et al 2009, Mohamed and Abdelatif 2010).

Our results agree with those reported in Angora rams by Loubser and van Nie Kerk (1983) who found that the concentration does not change with the season. The effect of the season would include variations due to photoperiod or treatment with melatonin (Chemineau et al 1988, Lindsay 1991). However, Kaya et al (2000) and Faigl et al (2009) did not find a significant effect of melatonin administration on concentration even outside the sexual season.

Contrary to the results of Ghozlane et al (2005), Tabbaa et al (2006) and David et al (2007), the concentration was not correlated with the mass motility nor with the volume of the semen (tables 3 and 4).

Number of straws

According to our results, there was no statistically significant influence of the effect of season and age on the number of straws produced. On the other hand, some authors indicate that there is a seasonal variation in the number of spermatozoa per collection in relation to seasonal photoperiodism in rams (Gundogan and Demirci 2003 under European continental climate, Rege et al 2000 in Ethiopia).

According to Chemineau et al (1988) the rams produce more sperm in short days; an increase in the amount of semen can be produced through the use of melatonin implant or photoperiodic treatment in small ruminants.

Conclusion

• The ram’s age category effect was shown to be a factor of variation. Quantitative production of sperm was higher in adults than in young. This difference was very significant (P <0.0001) for the mass motility, and significant for the concentration (P <0.036), but not significant for the two other parameters (volume and number of straws).
  
  
• The quantitative parameters of the sperm of Ouled-Djellal rams were subject to seasonal variations, they do not all vary in the same way. In autumn and spring, the volume of ejaculate, the concentration and the number of the straws of the rams were somewhat greater, unlike winter and summer. But the effect of the season had a highly significant influence only on volume (P <0.001) compared with the other three parameters (concentration, number of straws and mass motility). The number of straws per ram was not significantly influenced by seasonal factors (P <0.075) and age (P <0.089): 12.4 ± 1.5 per week.

Acknowledgments

We thank the officials and workers of the National Center for Artificial Insemination and Genetic Improvement, in particular Dr Boudjakdji Abdelkrim and Dr Abdelayidoum Ahmed for their invaluable help in carrying out this work. Our thanks also go to Dr. Aissat Saad for his thoughtful advice in the drafting of this article.

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Received 5 October 2017; Accepted 7 November 2017; Published 1 January 2018

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