Field scale evaluation of semen diluents for cervical AI in sheep: An
attempt at technology transfer
AgResearch Dairy and Beef Division, Ruakura Research Centre,
Private Bag, 3123, Hamilton, New Zealand
Proceedings of the New Zealand Society of Animal Production. 1995,
55: 232-235
A new semen diluent RSD-1 has been developed which considerably
enhances the storage life of ram semen, (at 15 C) when assessed by
measurements of the percent sperm motile in the laboratory. This enhanced
storage life could potentially overcome the current time constraints on the
use of fresh ram semen (within 12 h of collection) when held at 15 C for AI.
Field trails were conducted on commercial farms to compare the new diluent
with the standard diluent (milk), with semen being cervically inseminated on
the day of collection (6-12h storage) or the next day (30-36 storage). Trial 1
and 1992 involved 1127 ewes inseminated with semen from 8 rams on 10
farms in Otago-Southland. Trial 2 (1993) involved 1617 ewes, 16 rams and
11 farms and Trial 3 (1994) 1319 ewes, 10 rams, and 9 farms. There were
significant effects on pregnancy rate, after cervical insemination, of diluent
type (P<0.01), with milk being better than RSD-1 (29.6% vs 19.4%), and of
storage time (P<0.01) with the day of collection being better than one day
later (35.7% vs 13.3%). These overall differences were small compared to
those between farms (11 to 44%, P<0.01) and between rams (10 to 38%,
P<0.01).
In February 1994 an additional pre-season trial was conducted on a research
station involving 535 ewes inseminated cervically with semen from 9 rams
in which minor modifications to the RSD-1 diluent were compared to the
milk diluent. In this trial there was a significant effect on pregnancy rate
after insemination of oestrous status (P<0.01) at time of AI (oestrus 57.3% vs
not oestrus 37.9%) and of rams (P<0.001; 17 to 60%) but no significant
effects of diluent nor of storage time.
These results show that the beneficial effects of the new (RSD-1) diluent as
assessed by maintenance of percent sperm motile in the laboratory are not
reflected in enhanced conception rates with cervical insemination. Thus re-
evaluation of the techniques used for the determination of sperm viability are
required. Also the major effects of rams and their interactions with diluent
type and storage time on conception rates that were shown in these trials
require further investigation.
Keywords: NZSAPAB;
semen diluents; cervical AI; rams; field trials; storage time
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Last Updated 25-01-1997
