VIe CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. I

The area has achieved a 90/120 day non-return rate over 18,000
inseminations of 68.1%.

Pelleted semen and lst day liquid semen was used at the same
time in our mainland Sub-Centres from September 1965 to July 1967.
Some 2nd day liquid semen was used early in the period but was
discontinued owing to the lower conception rate obtained.

TABLE III A comparison of the conception rate obtained with lst
and 2nd day liquid semen with that of pelleted semen (9Q/12O day ).

_ Pellet 1st day liquid |2nd day liquid

65.1 67.4 63.1 ] |

Inseminations
The pellet conception rate was significantly lower than that
of first day liquid semen but did not differ significantly from 2nd
day rate.

It has been reported by Isbister (3) that the decline between
30/60 day and 90/120 day non return rates is significantly greater
(1.9%) for semen frozen in ampoules. The comparable figures for
fresh and pelleted semen shows no significant difference.

TABLE IV A comparison of 30/60 day and 90/120 day non return rate
for liquid and pelleted semen (December 1965 to November 1966 ).

Number of 1lst| 30/60 day 90/120 day
Inseminations Non return | Non return Difference

    
 

   
 

  

  

% Non=return

 

Pellet 25,663
Liquid 37,071

P> 0.3

Out of 1458 ejaculates frozen only 17 were unsuitable for use

It was found that the average percentage of live spermatozoa
before freezing was 72% and the average live sperm lost during the
freezing process was 18%.

The results showed that the non return rate was not affected by
the numbers of live spermatozoa per pellet within a range of 10 - 35
million.

Discussion

The freezing of bovine semen in pelleted form provides an
acceptable alternative to liquid semen. Although the pellets did not
quite obtain the fertility level of liquid semen used on the day of
collection, the wastage of semen was reduced and maximum use could
be made of outstanding sires.

There appears to be no advantage gained from the addition of
antibiotics to the pelleted semen.

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