ROLE OF ZINC SUPPLEMENT IN WEIGHT GAIN,
TESTICLE DEVELOPMENT AND
SEMEN CHARACTERISTICS OF YOUNG RAMS

Sarlós, Péter
Rózsa, László
Molnár, András
Rátky, József
Research Institute of Animal
Breeding and Nutrition
Herceghalom, Hungary

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ABSTRACT

The vital importance of zinc was proven in 1935 by Todd et al. in their experiments on rats. However, practical significance of this element was only recognized in the fifties when the parakeratosys of swine was identified as zinc deficiency disease. Experiments on various animal species proved that zinc was one of the most important micro-elements in physiology. It plays an essential role in several biological processes and is a constituent of many enzymes. It is well-known from literature that zinc is necessary for the development of male reproductive organs and in spermatogenesis. Zinc deficiency can cause a drop in performance that presents itself in poor appetite, slow development, protein metabolism problems, hindered testicle development and lower fertility.

A feeding experiment was carried out on young rams supplied with sufficient amounts of micro-elements. The effect of extra zinc supplement on weight gain and testicle development and later on semen production, was studied. In two groups (seven animals each) rams were given a micro-element supplement in the form of dried, inactivated yeast enriched with zinc for 100 days from the age of 60 days - group I: 16 mg Zn/day/lamb, group II: 32 mg Zn/day/lamb. The control group was only given pure yeast.
From the beginning of feeding up to seven months of age the second group completed 255.9 percent weight gain. This exceeded the results of the first (225.4 percent) and the control groups (228.2 percent) by 28 percent and 30 percent, respectively. The average daily weight gain in this period was as follows: group I: 213g, group II: 237g, control group: 223g. There was a significant difference in the development of testicles as well.
The increase in testicle diameter in the second group was 28 percent and 34 percent higher than that in the first and the control group, respectively.
The difference in zinc content of wool between groups and among individuals was not significant in this period.
Ejaculate was collected from rams 9-12 times from the age of seven months. The results of semen examination did not show significant differences between the groups in characteristic values. The average amount of ejaculate was: group I: 1.04ml, group II: 1.13ml, control group: 0.98ml. Sperm abnormalities stayed under ten percent in every group, group I: 7 percent, group II: 9.1 percent, control group: 5.88 percent. Results of sperm motility examinations were almost uniform.
According to these results extra zinc supplement in addition to sufficient amounts of micro-elements has a positive effect on the weight gain of young rams, influences favourably the speed of testicle development, although examination of sperm at time of puberty did not show a significant qualitative or quantitative difference compared to the control group.

Table 1. Semen characteristics of adult rams after 100-days application of Zn

	Volume (ml) x s	Motility (1< 5) x s	Acrosomal defects % x s	Protoplasm a droplets % x s	Tail anomalies % x s	Head anomalies % x s	All anomalies % x s
Group I n= 55 Group II n= 60 Control n= 37	1.04 0.43 1.13 0.12 0.98 0.18	4.78 0.47 4.32 0.44 4.37 0.58	2.30 2.30 4.02 2.60 2.11 1.45	0.66 0.72 0.70 0.88 1.27 2.94	2.58 1.43 3.61 1.45 2.33 1.80	1.43 3.67 0.73 1.92 0.05 0.16	7.00 4.66 9.18 4.16 5.88 4.97

Table 2. Changes of Zn content of wool during the experiment

Table 3. Experimental animals

Table 4. Average daily weight gain

Table 5. Growth rate of body weight and testicular diameter

Figure 1. Effect of Zn-supplementation onto the growth rate of ram hoggets

Figure 2. Effect of Zn-supplementation on the growth rate of testicular diameter of ram hoggets