the pellet and the rapid than those in the slow freezing. The
results do not confirm the author's last report (6). The
reasons are not clear, but it may be due to differences among
bulls, seasons and no. of samples, From the results, cryo-
protectives could be divided into two groups. One group gave
good protection only in fast freezing (sugar, sugal alcohols and
inositol) and the other gave same results only in slow freezing
(ethylene glycol and glycerol). Difference in the protection by
freezing rates between the two groups may be due to differences
in the eutectic points. The results also mean that bull
spermatozoa withstands fast freezing, but glycerol decreased
this capacity. In almost all reports on freezing of bull semen,
these authors asserted that bull semen has to be frozen at slow
to prevent '"cold shock'. But these experiment were made using
only glycerol as the protective agent.

Fertility results of the pelleted semen are given in Table 1.

In this trial, 0.932-1.63 (108) of spermatozoa was used at
a insemination. Conception rates using non-glycerol egg-yolk
sugar extenders were good and about the same as those for fresh
semen.,

REFERENCES

(1) H. NAGASE, 1962, Proceed. 54th Meet, Jap. Soci. Vet. Sci.,
24,505 (Abst.) In Japanese

(2) H. NAGASE, T. TOMIZUKA, K. TAMURA, R. ASANUMA and S. SHIRAI,
1966, Jap, J. Zootech. Sci. 37, (Supplement) 34, In Japanese

(3) H. NAGASE, T. NIWA, S. YAMASHITA and S. IRIE, 1964, Proceed.
5th Intern Congr. Anim. Reprod, and A. I., 4,387

(4) H. NAGASE, T. TOMIZUKA, H. OSHIDA and T. MIKAWA, 1966, Kanto
Division Jap. Assn. Zootech. Sci. No. 2, 11, In Japanese

(5) H. NAGASE, 1966, Japan Agric. Res. Quat., 1, No. 2, 1

(6) H. NAGASE, T. NIWA, S. YAMASHITA and S. IRIE, 1964, Proceed.
5th Intern. Congr. Anim, Reprod. and A. I., 4,498

 

In Fig. 1, X,F,G,G1,M,5,L,R and Gly. indicate xylose,fructose,
galactose,glucose,maltose, sucrose,lactose,raffinose and glycerol,
respectively.

m2