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EFFECT OF FREQUENCY OF MINERAL AND VITAMIN SUPPLEMENTATION ON SEMEN QUALITY OF ANGORA GOAT SIRES

 

A. Baca#M.A. Snyman & E. Kilian

Grootfontein Agricultural Development Institute, Private Bag X529, Middelburg (E.C), 5900

#E-mail: Ayanda Baca

 

INTRODUCTION

Genetic improvement in a breed is dependent on the rate of genetic change achieved in stud animals. The rate and efficiency of distribution of these superior genetics to commercial flocks could be increased through artificial insemination with frozen semen. The low conception rates achieved with laparoscopic artificial insemination with frozen semen in Angora goats is unacceptable and would inhibit the widespread use of this technology in the industry. After five years of investigations, one of the problem areas identified is the variability and poor semen quality of Angora rams (Snyman, 2011), which means that a low percentage of semen ejaculates obtained, could successfully be frozen.

Several factors, including age (Toe et al., 1994; Al-Ghalban et al., 2004), body weight and condition (Alkass et al., 1982; Toe et al., 1994; Schulte-Hostedde et al., 2005), testis size (Lino, 1972; Ott & Memon, 1980; Langford et al., 1989), season (Greyling & Grobbelaar, 1983; Al-Ghalban et al., 2004) and nutrition (Martin et al., 1994a; Thwaites, 1995; Almeida et al., 2007) determine the quality and quantity of semen. The results presented by Parker & Thwaites (1972), Braden et al. (1974), Foote (1978), Oldham et al. (1978), Alkass et al. (1982), Fernández et al. (2004) and Kheradmand et al. (2006) confirmed that sperm production, as well as total number of spermatozoa per ejaculate, can be improved diet by increasing energy and protein levels in the diet. The proportion of live and dead spermatozoa is not affected by dietary treatment (Kheradmand et al., 2006).

Several studies have documented the interrelationship between energy intake and reproductive performance in adult rams (Braden et al., 1974; Rowe & Murray, 1984; Murray et al., 1990). It is well recorded that protein deficient feeding can reduce semen quality and sexual activity (Okolski et al., 1971; Brown, 1994). A deficiency in protein could be responsible for depressed testicular growth and spermatogenesis of rams (Oldham et al., 1978). This decline in reproductive performance as a result of protein deficiency in a diet has been well documented (Martin et al., 1994b). The effects of protein supply above maintenance requirements are unclear, with reports of either an increase or no changes in testicular size, semen quality, testosterone secretion or sexual activity (Oldham et al., 1978; Lindsay et al., 1984; Martin et al., 1994b; Boukhliq et al., 1997; Bielli et al., 1999; Fernández et al., 2004). Lupins fed at 0, 0.5, 1.0, and 2.0% of body weight to Merino rams for 11 weeks as supplements to a maintenance diet of grass hay, had a positive effect on testicular size (Ritar, 1984; Boukhliq & Martin, 1997a, 1997b), weights of the seminal vesicles and epididymides, Luteinising hormone and Follicle stimulating hormone (Pomares et al., 1995).

Zinc is essential in the production of many of the sex hormones, including testosterone and gonadotrophin releasing hormone (Hambidge et al., 1986). It is also involved in ribonuclease activity and spermatozoa maturation during spermatogenesis (Cheah & Yang, 2011) and enhances sperm motility. Supplementation with zinc increases daily sperm production and reduces the proportion of abnormal spermatozoa (Underwood & Somers, 1969). Zinc also has antioxidative properties and may also act to reduce the reactive oxygen species and hence increase fertility (Bray et al., 1997).

Selenium and Vitamin E play a biological role as cell antioxidant by preventing damage by oxygen and various peroxides formed from fatty acids (Smith & Akinbamijo, 2000, Cheah & Yang, 2011). Selenium is also required for the accurate formation of the midpiece and flagella (Cheah & Yang, 2011). Vitamin A is involved during spermatogonia differentiation and spermatid adhesion regulation (Cheah & Yang, 2011). An advanced deficiency of Vitamin A causes degeneration of the seminiferous tubules and testicular atrophy. Vitamin A and iodine deficiency impair the ram’s libido. Abdulkareem et al. (2005) found that supplementation of rams with 100 000 IU/month Vitamin A for twenty weeks improved their reproductive performance and fertility.

From the literature it is evident that high levels of energy and protein are needed to ensure high quality semen production. Energy and protein levels were therefore not evaluated in this study. Evidence also exists in the literature that supplementation with vitamins and trace minerals improves semen quality. The aim of this study was to determine which frequency of supplementation of vitamins (A, D, and E) and trace minerals would yield the highest quality semen of Angora sires, fed on a high quality energy and protein diet, for use in a frozen semen program. Simultaneously, the effect of supplementation with lupins on semen quality was also investigated.

 

MATERIALS AND METHODS

2011/2012 Trial

The trial was conducted at the Grootfontein Agricultural Development Institute (GADI) under kraal conditions. Four-tooth to eight-tooth clinically and reproductively sound Angora goat rams were used for this trial. Twenty-five rams from the Jansenville flock and 15 rams from a farmer in the Steytlerville district were used. The standard biosecurity procedures of GADI were followed on arrival of the rams from their respective locations. The study was done from November 2011 until March 2012 (2011/2012 trial).

Before the start of the trial, the rams were shorn and the GADI veterinarian carried out a genital soundness evaluation. The rams were divided on a stratified origin, age and body weight basis into four groups of 10 animals each. The rams were kept at GADI in kraals with adequate shade. The four groups received the treatments as summarised in Table 1 from the beginning of November 2011.

 

Table 1. Experimental layout for 2011/2012 trial

Factor

Group 1

Group 2

Group 3

Group 4

Diet

High protein diet + lucerne hay

High protein diet + lucerne hay

High protein diet + lucerne hay

High protein diet + lucerne hay

Embavit®

(Vitamin A,D,E)

Every four weeks starting November

Every six weeks starting November

Every eight weeks starting November

Every four weeks starting November

Embamin T.E.®

(Co, I, Se, Zn, Mn)

Every four weeks starting November

Every six weeks starting November

Every eight weeks starting November

Every four weeks starting November

Lupins

0 g/day

0 g/day

0 g/day

150 g/day

 

Due to the fact that literature evidence proved the positive effect of supplementation of vitamins and trace minerals on semen quality, and the limited number of rams available, no control group was included. The composition of the high protein diet is given in Table 2.

 

Table 2. Composition of the high protein pelleted diet

Feedstuff

Percentage

 Lucerne hay

31

 Maize stover

5

 Maize meal

45

 Fishmeal

2.5

 Cottonseed oil cake meal

15

 Feed lime

1

 Ammonium chloride

0.5

Total

100

Nutrient

Percentage

 Crude protein

16.1

 Energy (TDN)

68.5

 Crude fibre

13.6

 Ca

0.94

 P

0.39

 

The rams were adapted to the high protein pelleted diet as follows:

They received lucerne hay ad libitum plus 100 g pellets/ram/day for three days. Thereafter the pellets were increased by 100 g/ram/day until the desired amount of 1.5 kg/ram/day was reached. Lucerne hay was decreased to 500 g/ram/day when the full ration of pellets was reached. Half of the daily feed portion was provided in the morning and half in the afternoon. Group 4 received 150 g of lupins per day additionally.

Embamin T.E. (Reg.No. V8189 Act.36/1947) was prepared according to the label prescription by mixing 1 ℓ Embamin T.E.® with 9 ℓ of clean water. Each ram received 1 ml of the diluted Embamin T.E.® per 4.5 kg body weight orally according to the schedule indicated in Table 1.

Embavit (Reg.No. V8189 Act.36/1947) was prepared according to the label prescription by mixing 500 ml Embavit® with 2 ℓ of clean water. Each ram received 1 ml of the diluted Embavit® per 5.0 kg body weight orally according to the schedule indicated in Table 1.

From the beginning of the trial the rams were exercised daily during the week by walking them at a fast pace for at least an hour.

 

2012/2013 Trial

This part of the trial was done from October 2012 until April 2013 (2012/2013 trial). Twenty-five of the rams used during the 2011/2012 trial were used for this trial. The rams were divided on a stratified origin, age and body weight basis into two groups of 13 and 12 animals respectively. The rams were kept at GADI in kraals with adequate shade. The two groups received the treatments as summarised in Table 3 from the middle of October 2012. The same procedures were followed during this trial as during the 2011/2012 trial.

 

Table 3. Experimental layout for 2012/2013 trial

Treatment 

Group 1

Group 2

Diet

High protein diet + lucerne hay

High protein diet + lucerne hay

Embavit®

(Vitamin A,D,E)

Every six weeks starting November

-

Embamin T.E.®

(Co, I, Se, Zn, Mn)

Every six weeks starting November

-

Wheat germ oil

-

15 ml/day two times per week

 

 

Data collection during both trials

Genital soundness evaluation (GSE) was done at the start of the 2011/2012 trial. The GSE included the following: clinical examination, body condition score, eyes and eyelids, Famacha© anaemia score, teeth and bite, scrotal cover, palpation of testes, epididimi, lymph nodes and spermatic chords, testis tone, scrotal circumference, testis length, extent of ventral split in the scrotum, examination of the sheath and penis.

During the 2011/2012 trial, semen was collected on the following dates: 7 November 2011, 21 November 2011, 06 December 2011, 25 January 2012, 08 February 2012, 21 February 2012, 05 March 2012 and 20 March 2012. At first the semen was collected via electro-ejaculation, but after the third collection the rams were trained to donate semen via the artificial vagina. From the fourth collection onwards, semen samples were collected via artificial vagina from those rams that were using the artificial vagina, while the rest were electro-ejaculated. During the 2012/2013 trial, semen was collected on 13 collection dates starting from 20 February until 22 April 2013. During this trial, semen samples were only collected via artificial vagina from those rams that were using the artificial vagina.

Semen volume was measured with a calibrated collecting tube. The semen density was assessed on a scale that ranged from watery to milky to creamy (Evans & Maxwell, 1987). Semen colour was categorised as either yellow, cream, light yellow, white or pink for those samples contaminated with blood (Evans & Maxwell, 1987).

Wave motion and mass motility were assessed under a microscope for an undiluted sample using a scale of zero to five, with zero no motion and five very good progressive motion (Evans & Maxwell, 1987). The following stained smears were prepared to examine for percentage live and dead sperm and presence of infection during the 2011/2012 trial:

 

Statistical analyses of the data were performed using general linear (GLM) and categorical (CHI-SQUARE) procedures (SAS, 2009) to evaluate the effect of frequency of vitamin and mineral supplementation and lupins on semen quality. Chi-square procedures (SAS, 2009) were used to obtain frequency distribution tables for semen density and semen colour.

 

RESULTS

2011/2012 Trial

Means for body weight, scrotal circumference, semen volume, semen motility and percentage live sperm are presented in Tables 4 to 8. No differences in body weight were observed among the groups, except on 13 December 2011 (Table 4) when Group 2 and Group 4 had higher body weights (P<0.05) than Group 1. Group 2 had the highest (P<0.05) rut score on 5 March 2012, while no differences were observed on the other dates.

 

Table 4. Body weight (kg ± s.e.) of the different groups over the experimental period

Date

Group 1

Group 2

Group 3

Group 4

7 November 2011

58.84 ± 1.73

60.00 ± 1.64

58.94 ± 1.67

61.10 ± 1.61

13 December 2011

62.73a ± 2.25

69.68b ± 2.14

68.05 ± 2.18

70.95b ± 2.10

08 January 2012

70.24 ± 3.11

74.05 ± 2.95

71.30 ± 3.00

73.38 ± 2.90

08 February 2012

70.13 ± 3.05

70.90 ± 2.90

72.82 ± 2.95

70.63 ± 2.85

07 March 2012

68.11 ± 2.95

72.66 ± 2.99

70.85 ± 2.85

71.95 ± 2.75

20 March 2012

69.14 ± 3.05

75.48 ± 3.10

71.99 ± 2.95

72.30 ± 2.85

a,b Values with different superscripts differ significantly between groups (P<0.05)

 

Table 5. Scrotal circumference (cm ± s.e.) of the different groups over the experimental period

Date

Group 1

Group 2

Group 3

Group 4

21 November 2011

29.50a ± 0.85

26.46b ± 0.85

28.99a ± 0.81

29.87a ± 0.85

06 December 2011

30.28a ± 0.85

27.85b ± 0.81

29.89 ± 0.81

30.06 ± 0.85

25 January 2012

27.78 ± 0.84

27.58a  ± 0.83

29.95b ± 0.79

28.18 ± 0.79

08 February 2012

28.73 ± 0.83

26.86a ± 0.79

29.26b ± 0.81

29.53b ± 0.79

21 February 2012

27.73 ± 0.83

27.01 ± 0.79

29.17 ± 0.85

27.98 ± 0.79

05 March 2012

27.62 ± 0.84

28.39 ± 0.83

28.15 ± 0.79

28.23 ± 0.79

20 March 2012

27.47 ± 0.88

27.95 ± 0.83

29.06 ± 0.84

28.72 ± 0.83

a,b Values with different superscripts differ significantly between groups (P<0.05)

 

Significant group differences in scrotal circumference (Table 5) were observed on 21 November 2011, 06 December 2011, 25 January 2012 as well as 08 February 2012. During the last three collections, no differences were observed. Scrotum circumference of Groups 2, 3 and 4 increased with 1.95 cm, 1.71 cm and 0.96 cm, respectively, over the experimental period, while that of Group 1 decreased with 0.14 cm.

Semen volume (Table 6) of Groups 1 and 4 differed (P<0.05) from that of Group 3 on 08 February 2012, whereas Group 1 had higher (P<0.05) semen volume than Group 3 at the fifth and seventh collection dates (Table 6). Semen volume increased (P<0.05) with collection date.

 

Table 6. Semen volume (ml ± s.e.) of the different groups over the experimental period

Date

Group 1

Group 2

Group 3

Group 4

21 November 2011

0.84 ± 0.17

0.65 ± 0.17

0.57 ± 0.16

0.78 ± 0.17

13 December 2011

0.35 ± 0.17

0.41 ± 0.16

0.75 ± 0.16

0.56 ± 0.17

25 January 2012

1.16 ± 0.17

0.93 ± 0.16

0.92 ± 0.16

0.91 ± 0.16

08 February 2012

1.48a ± 0.17

1.17 ± 0.16

1.00b ± 0.16

1.45a ± 0.16

21 February 2012

1.62a ± 0.17

1.18 ± 0.16

1.10b ± 0.17

1.18 ± 0.16

05 March 2012

1.51 ± 0.17

1.26 ± 0.17

1.13 ± 0.16

1.29 ± 0.16

20 March 2012

1.76a ± 0.18

1.33 ± 0.17

1.07b ± 0.17

1.33 ± 0.16

a,b Values with different superscripts differ significantly between groups (P<0.05)

 

Table 7. Semen motility (± s.e.) of the different groups over the experimental period

Date

Group 1

Group 2

Group 3

Group 4

7 November 2011

3.59a ± 0.27

3.45 ± 0.29

3.36 ± 0.27

2.82b ± 0.27

21 November 2011

2.87 ± 0.27

2.92 ± 0.27

3.23 ± 0.26

3.37 ± 0.27

06 December 2011

2.70 ± 0.27

3.04 ± 0.26

2.98 ± 0.26

2.53 ± 0.27

25 January 2012

2.25 ± 0.27

2.91 ± 0.27

2.49 ± 0.25

2.47 ± 0.25

08 February 2012

2.40 ± 0.27

2.75 ± 0.25

2.83 ± 0.26

2.41 ± 0.25

21 February 2012

2.00 ± 0.27

2.21 ± 0.25

1.99 ± 0.27

2.12 ± 0.25

05 March 2012

2.07 ± 0.27

2.62 ± 0.27

2.42 ± 0.25

2.36 ± 0.25

20 March 2012

2.20 ± 0.28

2.50 ± 0.27

2.82 ± 0.27

2.17 ± 0.27

a,b Values with different superscripts differ significantly between groups (P<0.05)

 

A significant difference in semen motility (Table 7) was observed between Group 1 and Group 4 during the first collection date, with Group 1 having higher (P<0.05) semen motility. No further differences in semen motility were observed. Percentage live sperm (Table 8) was generally high and no specific trend among the groups was evident.

 

Table 8. Percentage live sperm (± s.e.) of the different groups over the experimental period

Date

Group 1

Group 2

Group 3

Group 4

06 December 2011

83.64 ± 2.56

80.30a ± 2.39

86.56b ± 2.00

86.13 ± 2.38

08 February 2012

82.44 ± 2.22

85.24 ± 2.23

86.13 ± 2.38

81.81 ± 2.24

21 February 2012

83.22ac ± 2.10

91.74b ± 2.09

88.62 ± 2.11

91.47c ± 2.08

05 March 2012

87.87 ± 2.23

86.12 ± 2.23

85.56 ± 2.00

87.19 ± 2.37

a,b,c Values with different superscripts differ significantly between groups (P<0.05)

 

The overall group averages for the different semen and testes traits for the 2011/2012 trial are summarised in Table 9. Group 2 had the highest semen motility, while Group 1 had the highest semen volume.

 

Table 9. Overall group averages for the different semen and testes traits

Trait

Group 1

Group 2

Group 3

Group 4

Scrotal cover

2.89abc ± 0.17

3.46a ± 0.16

3.54b ± 0.15

3.39c ± 0.16

Scrotal tone

3.86 ± 0.06

3.87 ± 0.06

3.77a ± 0.06

3.95a ± 0.06

Scrotal circumference

28.00a ± 0.32

27.26bc ± 0.30

28.98ab ± 0.30

28.79c ± 0.29

Testis split

1.70 ± 0.38

1.16 ± 0.36

1.01 ± 0.32

1.43 ± 0.34

Testis length

8.87a ± 0.17

8.30a ± 0.16

8.47 ± 0.16

8.54 ± 0.16

Groin colour

1.85 ± 0.13

1.93 ± 0.12

1.85 ± 0.12

1.93 ± 0.12

Semen motility

2.51ab ± 0.10

2.80ac ± 0.10

2.76b ± 0.09

2.53c ± 0.09

Semen volume

1.25abc ± 0.07

0.99a ± 0.06

0.93b ± 0.06

1.07c ± 0.06

a,b,c Values with the same superscripts differ significantly between groups (P<0.05)

 

The overall percentage distributions of the different groups for semen density are presented in Table 10. Significant differences among the groups were observed with regard to semen density. The majority of samples in each group were classified as thin cream.

 

Table 10. Percentage distribution of the different groups for semen density (2011/2012 trial)

Group

Watery

Thin milk

Milky

Thick milk

Thin cream

Creamy

Thick cream

1

15.49

8.45

16.90

9.86

45.07

1.41

2.82

2

8.11

14.86

17.57

13.51

32.43

8.11

5.41

3

10.39

6.49

23.38

6.49

29.87

7.79

15.59

4

18.42

5.26

27.63

6.58

32.89

6.58

2.64

 

The overall percentage distributions of the different groups for semen colour at the various collection dates are presented in Table 11. No significant differences among the groups were observed with regard to semen colour. The majority of samples in each group were classified as cream.

 

Table 11. Percentage distribution of the different groups for semen colour (2011/2012 trial)

Group

Yellow

Cream

Light yellow

White

Pink

1

15.49

61.98

4.23

18.30

 

2

17.57

59.46

6.76

14.86

1.35

3

19.48

64.94

6.49

9.09

 

4

10.53

67.10

2.63

18.42

1.32

 

2012/2013 Trial

The body weight of the different groups is presented in Table 12. No differences in body weight were observed among the groups.

 

Table 12. Body weight (kg ± s.e.) of the different groups over the experimental period

Date

Group 1

Group 2

October 2012

66.6 ± 2.8

66.7 ± 2.8

November 2012

70.2 ± 2.9

71.1 ± 2.9

December 2012

74.7 ± 3.4

76.3 ± 3.4

January 2013

80.9 ± 3.8

82.7 ± 3.7

February 2013

81.9 ± 3.5

81.3 ± 3.5

March 2013

78.1 ± 3.1

75.7 ± 3.1

 

Semen volume of Group 1 and Group 2 differed (P<0.05) on 15 and 17 April 2013, with Group 1 having a higher (P<0.05) semen volume than Group 2. At the beginning of the trial, the semen volume for Group 1 and Group 2 was 1.52 ± 0.22 and 1.14 ± 0.14 respectively. There were some fluctuations in semen volume throughout the trial. No significant difference in semen colour between groups was observed. Furthermore, no significant differences in semen mass motility were observed between Group 1 and Group 2 over the trial period. The initial motility score was 2.56 ± 0.41 for Group 1 and 2.14 ± 0.27 for Group 2. At the last collection, Group 1 had a mass motility of 1.97 ± 0.24, compared to 1.96 ± 0.26 of Group 2. The overall group averages for the different semen and testes traits for the 2012/2013 trial are summarised in Table 13. Group 1 had higher semen volume than Group 2.

 

Table 13. Overall group averages for the different semen and testes traits

Trait

Group 1

Group 2

Semen motility

2.40 ± 0.11

2.47 ± 0.10

Semen volume

1.22a ± 0.06

1.09b ± 0.06

a,b Values with different superscripts differ significantly between groups (P<0.05)

 

The overall percentage distributions of the different groups for semen density are presented in Table 14. No significant differences among the groups were observed with regard to semen density. The majority of samples in Group 1 were classified as thin cream, while the majority of samples in Group 2 were classified as milky.

 

Table 14. Overall percentage distribution of the different groups for semen density evaluated during the 2012/2013 trial

Group

Watery

Thin milk

Milky

Thick milk

Thin cream

Creamy

Thick cream

1

12.77

 

30.85

2.13

37.23

17.02

 

2

6.38

 

38.30

3.19

34.04

15.96

2.13

 

The overall percentage distributions of the different groups for semen colour at the various collection dates are presented in Table 15. No significant differences among the groups were observed with regard to semen colour. The majority of samples in each group were classified as cream.

 

Table 15. Overall percentage distribution of the different groups for semen colour evaluated during the 2012/2013 trial period

Group

Yellow

Cream

White

1

30.85

67.02

2.13

2

36.17

63.83

 

 

DISCUSSION

Semen traits recorded in these trials compare well with literature values available for goats (Loubser & Van Niekerk, 1983; Oyeyemi et al., 2000). Semen volume in these trials (0.93 to 1.25 ml) was similar to the value recorded for Angora rams (1.09 ml) by Loubser & Van Niekerk (1983), but higher than those recorded for various groups of West African dwarf goats (0.36 to 0.44 ml) (Oyeyemi et al., 2000). Semen volume of Control (0.91 ml) Ossimi rams was lower than that of rams receiving injections of Vitamin E and Se (1.05 ml) (Mahmoud et. al., 2013).

Semen density determines the number of straws or pellets that could be frozen from 1 ml of semen. Around 50% of the samples had a density of thin cream or better, meaning a concentration of more than 3x109 sperm/ml. Semen colour recorded for West African dwarf goats was also white to cream (Oyeyemi et al., 2000).

On request of technicians at Ramsem, the semen mass motility assessment scale was downgraded, i.e. a mass motility that should normally be awarded a score of 4+ or even 5, should be a 3 according to their scale. Therefore, the mass motility scores recorded in these trials are lower than those reported in literature. Mahmoud et al. (2013) reported values of 3.17 for control and 4.05 for rams receiving injections of Vitamin E and Se. Loubser & Van Niekerk (1983) reported an average value of 3.25 for Angora goats.

Percentage live sperm recorded in these trials falls within the upper ranges recorded in the literature. It was lower than values recorded for West African dwarf goats of 96.2% to 96.6% (Oyeyemi et al., 2000), but higher than those recorded for Angora goats (50.78%; Loubser & Van Niekerk, 1983). Mahmoud et al. (2013) reported values of 50.05% for Control and 72.75% for rams receiving injections of Vitamin E and Se.

 

CONCLUSIONS

Although supplementing at six or eight week intervals yield better results in terms of semen density and motility, there were no consistent differences in the frequency of supplementation of vitamins (A, D, and E) and trace minerals to Angora rams on testes traits or semen quality. Supplementation with lupins did not have an effect on the testes and semen quality traits. Semen motility and percentage of live sperm in the majority of the rams were good and should not provide a problem for freezing. The high energy and protein diet provided, together with six-weekly supplementation of vitamins and trace minerals to Angora rams subjected to a regular exercise program should ensure semen of good enough quality for a freezing protocol.

 

ACKNOWLEDGEMENTS

Mr Ray Hobson and the Eastern Cape Department of Rural Development and Agrarian Reform, Jansenville Experimental Station are thanked for provision of the animals for these trials.

 

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Grootfontein Agric 14 (1) (11)