A NOTE ON LENGTH OF OESTROUS CYCLE AND DURATION OF PREGNANCY IN ROMNEY EWES.

New Zealand Journal of Agriculture, Volume 47, Issue 6, 20 December 1933, Page 386

A NOTE ON LENGTH OF OESTROUS CYCLE AND DURATION OF PREGNANCY IN ROMNEY EWES.

F. W. Dry,

Massey Agricultural College, Palmerston North.

This note is intended to supplement the records published by Mr. D. A. Gill in this Journal for November, 1933. The sheep were again Romneys, being cull studs or flock (non-stud) ewes from stud-breeders, or bred on the College farm from such animals. As at Wallaceville, the figures presented are to be regarded as the by-product of a piece of research.

In certain breeding work in 1931 it was necessary to know the length of the gestation period. Matings of like with like were made for several different fleece types, so that seven rams were being used with little more than a hundred ewes. The ewes were therefore kept in a paddock with teasers smeared over the brisket in the usual way with a coloured preparation. The ewes were constantly under the observation of Mr. R. Dossor, who was in charge of them. As soon as a ewe was found to have been marked by a teaser she was taken to the yards and served by the appointed ram. After service the ewes were kept away from all rams for a couple of days or so, and then placed in another paddock with teasers smeared with a preparation of a different colour. Length of Oestrous Cycle. Twenty-three ewes returned once to the ram and seven a second time, so that thirty-seven records were obtained of the interval between the beginning of one period and the beginning of the next. One interval was quite exceptional, being only seven days, to the great surprise of Mr. Dossor. With the procedure described there was, of

course, no doubt about the two services. This ewe returned a second time, twenty days later, and proved empty. Omitting the one exceptional figure the records are as follows :— Interval in Days. Number of Returns. Interval in Days. Number of Returns. 14 I 18 3 15 1 19 1 16 13 20 .2 • x 7 14 21 1 The average for the above 36 figures is just under 17 days. For ewes that returned twice the intervals, in days, were as follow, the first interval being given first : 14 and 15, 16 and 16, 16 and 17 .(twice), 17 and 17, 18 and 17, as well as 7 and 20.

Duration of Pregnancy. My records for the duration of pregnancy run very parallel to those of Mr. Gill. There was less variation in the times than I had hoped, the shortest being five days less than 149 days, and the longest four days more than that time. The purpose of the investigation was to look for a possible correlation between the length of gestation period and the intensity of the pre-natal check revealed by the fibre type array on the standard position on the back. (This Journal, May, 1933 and New Zealand Journal of Science and Technology, XIV, 6, 1933.) I had wondered whether a short gestation period might result in a slight pre-natal check, a longer gestation period in a more intense one, but no correlation of this kind was revealed. The data are as follows :—

The average for 107 ewes is 148-7 days, which is in exact agreement with Mr. Gill’s figure.

Supplies of Limonite Ore. — Samples of limonite from a number of localities, several being in the vicinity of Rotorua, have been examined by the Chemistry Section, Department of Agriculture, as to suitability for stock-lick purposes. he majority have been of too low grade, or present in insufficient quantity, to be able to compete with the Whangarei material, the only exception being a very high-grade ore from Okaihau, Bay of Islands.

Inoculation of Lucerne. — The Mycology Section of the Plant Research Station reports that during the year 1932-33 cultures of the lucerne nodule organism were distributed in quantity sufficient to inoculate 69,500 lb. of seed, showing an increase of 80 per cent, over the previous season. The cultures were forwarded to 1,037 farmers, an increase of upwards of 40 per cent.

Duration of Pregnancy, in Days. Number of Ewes. Single Births. Double Births. Triple Births 144 I I 145 3 3 146 9 5 . 4 147 15 8 6 I 148 . . 22 16 6 149 19 15 ' 4 150 18 14 4 151 14 11 3 152 3 3 153 3 1 2