The preferred mating period in Greece is spring and early summer. Conception rate to natural mating at the end of one oestrus period or early in the next is low, leading to a lengthy lambing period. Some 10% of flocks are synchronised during this period by a standard progestagen/PMSG treatment. There is considerable variation in ovulation rate, conception rate and litter size which could be related to within-flock variation in oestrous activity.

Fourteen adult ewes from each of three breeds -Chios, Karagouniko and Serres - were maintained as a single flock at Diavata (latitude 40.5°N), without mating, from the end of the milking period in September. From the following April, oestrous activity was checked daily by vasectomised ram for 18 months. Live weight was maintained approximately constant at 59, 54 and 54 kg, respectively, for Chios, Karagouniko and Serres. Plasma progesterone was measured 10 days after detected oestrus and after 28 days when there was no intermediate activity. A silent oestrus in the breeding period was counted as oestrus but when it occurred prior to the first or after the last detected oestrus, it was not used to determine the breeding period.

The indigenous sheep breeds in Greece have a relatively short anoestrus. Some ewes begin to cycle before June but there is considerable variation, both between the within breeds, which may be associated with genotype or with environmental factors. Mating in spring or early summer, with or without synchronisation, is a common practice in order to take advantage of the climatic conditions and of the traditional marketing period for suckled lambs. In many cases the ewes are still being milked daily and are in low body condition. Conception rate is often low and the lambing period - in flocks of around 100 ewes - may extend over several months. Melatonin is known to advance the onset of oestrus in autumn breeding ewes but treatments initiated before June have given equivocal results.

Daily oral dosing in mid afternoon with 3 mg of the indoleamine, melatonin, from early June onwards is highly effective in advancing the breeding season of both Greyface and Scottish Blackface ewes kept under a natural photoperiod; the mean reaction interval from initial dosing to the onset of ovarian activity in Scottish Blackface ewes being around 65 days compared with 110 days for untreated controls (Robinson et al 1985). Advancing the starting time for the melatonin treatment to mid-March gave a similar reaction interval with behavioural oestrus occurring in late May/early June (Wigzell et al 1986a). Following this reversal of the breeding season by melatonin, continued melatonin treatment in unmated ewes resulted in a period of oestrous cyclicity lasting 4 to 5 months. Thereafter the ewes became refractory to melatonin and returned to anoestrus at a time when untreated controls were commencing ovarian activity (Wigzell et al 1986b). These observations prompted us to investigate the effects of different durations of melatonin treatment on ovarian activity.

Both the introduction of rams and treatment with melatonin will hasten the onset of the breeding season of sheep. The response of British breeds of sheep to the introduction of rams is generally considered to be confined to a period of only a few weeks before the usual date of onset of the breeding season (Fraser, Stamp and Cunningham, 1987). However, treatment with melatonin and the “ram effect” may work synergistically as melatonin would be expected to advance the period when the ewes are sensitive to the introduction of rams. This experiment investigated the hypothesis that exposure to high, sustained levels of melatonin from an intravaginal implant would lead to a response to the introduction of rams in mid-seasonal anoestrus similar to that obtained around the onset of the breeding season.

The introduction of rams to seasonally anovular ewes, pre-conditioned by a period of isolation, may induce the episodic release of LH, follicular development and ovulation in the ewes. The CL formed after ovulation induced by the introduction of rams may not persist for a full luteal phase; some ewes may ovulate again, while others may lapse back into seasonal anoestrus. An injection of progesterone at the time of ram introduction has been shown to overcome the premature regression of CL (Martin et al., 1986). This experiment investigated the effects of giving progesterone at the time of ram introduction upon the response of two types of ewe treated during June and July.

The introduction of rams to seasonally-anovular ewes will, at certain times of the year, stimulate increased pulsatile release of LH, follicle development and ovulation (Martin et al., 1986). The neuroendocrine mechanism governing the transition into adulthood of ewe lambs is incompletely understood, but it is believed to be similar to that which controls the transition to the breeding season in the adult ewe (Foster, Yellon and Olster, 1985; Legan, Karsch and Foster, 1977). Thus the introduction of rams may have a similar action in the pre-puberal ewe lamb as in the seasonally-anovular adult ewe. This experiment investigated the effect of the introduction of rams on the pattern of LH secretion and follicle development in ewe lambs during the late summer/early autumn of their first year of life.

By lambing upland ewes in May, it is possible to match the ewe's nutritional needs closely with grass growth (Newton et al 1982). Requirements for high cost housing and supplementary feeding during late pregnancy can be minimised. The resulting late born lambs should be available for sale as ‘out of season’ lamb when prices are at their highest. Delayed tupping, however, has been shown to reduce lambing performance in most breeds due to a lower ovulation rate (Land et al 1969). Ewe fertility, by contrast, is not affected as oestrus is strong with most indigenous breeds until February (Wheeler et al 1977). This experiment was designed to study the long term management requirements and performance of a late lambed (1 May to 5 June) flock and the efficacy of androstenedione (Fecundin) as a means of improving ovulation rate.

In ewes rearing triplets high milk yields in early lactation are vitally important. The trial was conducted to investigate the influence of dietary protein intake on ewe milk yield and the performance of their triplet reared lambs.

The trial involved 24 Cambridge (C) and 12 Suffolk x Cambridge (SxC) ewes rearing triplets. Ewes and their lambs were housed and penned in individual family groups until 35 days post partum. During the 7-35 day period ewes were fed ad libitum one of two coarsely milled complete diets differing in protein concentration (Table 1) together with a daily allocation of 510 g hay (oven dry).

Limited work has been carried out on straw feeding to pregnant ewes. The present study aimed to assess intake and performance of ewes when fed diets based on either barley or pea straw.

One hundred and forty mule ewes were randomly allocated to basal diets of pea or barly straw 15 weeks prior to lambing and allowed access to straw prior to housing to allow diet familiarisation. Pregancy diagnosis was performed at 75-80 days of gestation using real time ultrasound scanning. All in-lamb ewes were housed and grouped according to predicted foetal load. Ewe liveweight and condition was assessed at housing, 6 and 4 weeks prior to lambing and immediately after lambing.

Straw was available ad libitum and was supplemented with 400 g/day distillers dark grains. From 6 weeks prior to lambing whole barley with an inclusion of 15% fishmeal was fed twice daily up to a level of 600 g/day for ewes carrying twins and triplets and 400 g/d for ewes carrying singles.

Higher lamb growth rates have been observed on swards that increased in height over time than on swards of constant or decreasing height (Doney et al, 1987; Lloyd et al, 1987). Where ewes and lambs were maintained at sward surface heights (SSH) within the ranges 4-6 cm or 6-8 cm until weaning in August, high rates of lamb growth were achieved until the end of June whereafter there was a marked decline (Keeling et al, 1987). The present study investigated the effect on lamb performance of increasing sward height at the end of June.

One hundred and fifty Mule ewes with Suffolk cross lambs were grazed on an area of permanent grass (89% perennial ryegrass) which received 255 kg N/ha over the season in 4 dressings with balancing P and K. The initial stocking rate was 19 ewes and 31 lambs/ha and SSH was maintained in the range 4-6 cm from May 6 until the end of June.

Sward growth rate and height decline under autumn grazing in the UK. This eventually depresses ewe intake, live weight and body condition and may, as a consequence, reduce reproductive performance. The provision of supplementary feeding is a strategic measure to avoid this but requires quantification in relation to measurable variables such as sward height and stage of the reproductive cycle.

A management decision rule for supplementary feeding over the mating period, which is currently operated in the MLURI upland system studies, requires that, in order to maintain both body weight and condition until the completion of the second cycle of mating, concentrated feed be introduced when sward height (herbage mass) is ≤3.5 cm (≤1200 kg DM/ha), be increased when height is ≤3.0 cm ( ≤ 1000 kg DM/ha) and ad lib, hay be introduced when height is ≤ 2.5 cm (≤ 750 kg DM/ha).

With increasing flock sizes and the uncertainty of the hay-making process, silage has a part to play as the basal diet of Greyface type ewes during the latter half of pregnancy. Silage also varies considerably in feeding value and there is a demand for advice upon the contribution which grass silage can make to the diet, and also what level of concentrate feeding should be associated with any given silage. Silage is commonly subjected to a number of laboratory analytical procedures to provide estimates of:

The present series of feeding experiments sets out to provide evidence about the voluntary intake of a range of silages by ewes in late pregnancy and to examine any relationships which would help in predicting intake from laboratory analysis.

The effects of plane of nutrition on the body composition of growing sheep are very apparent when animals are compared at the same age following different nutritional histories. These differences are, however, less obvious when animals of the same breed and sex are compared at the same body weight and at present there is some conjecture whether composition is affected by growth rate. This uncertainty is not limited to fat and protein but includes the bone and ash, fraction and the ash composition.

The primary objective of this trial was to study the effects of different growth rates achieved by feeding different amounts of the same concentrate diet on the composition of empty-body gain and on the retention of minerals by growing lambs. A secondary objective was to examine the effect of adding supplementary calcium carbonate to the basal diet at the fast rate of growth.

Body condition score has been shown to be highly correlated to the degree of body fatness in slaughtering experiments involving a pre-established range of body condition score in sheep at the same physiological stage,but there is a lack of evidence in animals at different physiological conditions. The aim of the present work was to evaluate the usefulness of subjectively assessed body condition score to predict the proportion of chemical fat in the body of Romanov x Rasa ewes at different stages of their reproductive cycle. An adaptation of Russel et al.(1969) condition scoring system was used in wich animals were scored on a 0 to 5 scale to the nearest 0.25 condition unit.

There is a continuing requirement to improve the lean content of meat, efficiently produced, as food for human consumers. Hormonal anabolic compounds which stimulate the deposition of lean tissue and reduce fat accretion in ruminant animals are not permitted in the UK. In the absence of the use of such exogenous compounds, alternative currently practical means of manipulating body composition include the use of genetic selection and alterations in nutrition. The objective of the present study was to investigate the effect of diets differing in the source of carbohydrate and in protein level. The diets chosen were based on barley (diet B) in which starch predominates and sugar beet pulp (diet P) which contains greater quantities of cellulose and hemi-cellulose.

Twenty-eight crossbred (Suffolk ♂ x mule ♀ )entire male lambs were used in the experiment. They were housed at approximately eight weeks of age in individual slatted-floor pens and gradually introduced to experimental diets over a period of three weeks prior to the commencement of the study. Four pelleted diets were offered.

There are many locally-named breeds in Greece, all of which are derived from Zackel or Tsigai types in various combinations. One of the most numerous is the Karagouniko, described as a medium-sized, hardy breed of Zackel origin, probably with some introduction of a fat-tail breed. A ewe in good body condition weighs about 60 kg. In most regions there is little consistent breeding policy except to improve milk production and fecundity of the local breed by crossbreeding to the semi-indigenous Chios or, less commonly, the imported East Friesland. The Chios is reputed to be derived from a Turkish fat-tail breed crossed with ingenous sheep of Zackel and/or Tsigai origin. Adult ewes in good condition weigh around 65 kg.

The traditional marketing period for lambs is December to Easter and 80% are sold off milk at an age of 30 to 50 days and a carcase weight (including head) of 5 to 9 kg. Despite the highest, number of sheep per head of population in the EEC, some 16% of consumption is imported, usually in the 13 to 15 kg carcase range. The consumer discriminates against fat but there is no recognised standards of assessment or grading.

Upland pasture improvement can induce sub-clinical cobalt deficiency in grazing animals, leading to lowered productivity. A trial was set up to investigate three methods of combating this problem, namely: monthly vitamin B12 injections, administration of a slow-release bolus at the start of the grazing season and treatment of the pasture with cobalt sulphate.

A recently improved permanent grassland of 5 ha was split in two and one half treated with cobalt sulphate at 2 kg/ha. During two summers, 15 Blackface ewes with twin lambs grazed each pasture. One lamb from each pair on the untreated pasture was treated by monthly 1000 µg vitamin B12 injections in the first year, or by the administration of slow-release bolus in the second. Monthly measurements were made of liveweight, serum vitamin B12 and herbage Co.

Cobalt application to the pasture effected an immediate increase in herbage Co and maintained higher values for the whole of the first grazing season. The high value found one month after application would be due to leaf adherence.

In recent years, an increasingly high proportion of the country's ewes have been housed indoors for lambing, penned at high population densities. When observing suckling, for other purposes (Horrell et al. , 1987), we noticed that there seemed to be frequent disturbances of the normal suckling routine. The general pattern of suckling in extensive conditions has been described (Ewbank 1967). It involves suckling at fairly regularly intervals, with uninterrupted sucking for a period of 1-5 mins (in the first week) declining to 10-25 seconds in older lambs, until either the ewe moves away or the lamb ceases spontaneously; lambs rarely attempt to suck at unrelated ewes and twins tend to suck together. In contrast, we saw many attempts by lambs in indoor pens to suck at unrelated ewes, and ongoing suckling often seemed to be disturbed early on by alien lambs intruding, aggression on lambs by the ewe, lambs knocked off by other ewes, and other external events. If these differences are considerable, Intensive lambing conditions may have important implications for the efficiency of milk interchange. This project was designed to compare systematically the pattern of suckling in extensive and intensive conditions and to quantify the Incidence of various disturbances of suckling.

It is well established that the dairy cow experiences a period of dietary energy deficit in early lactation. With its high energy density, fat has tremendous potential as a dietary supplement at this time providing it is included in a form and at a level which does not interfere with rumen function. The paper presents results from a trial investigating dairy cow performance when fed concentrates containing either a liquid (LF) or a dried protected fat (DF).

Over recent years there has been increasing interest in the diversity of materials which may be used as energy sources in dairy cow concentrates. Traditionally, many dairy concentrates have been based upon cereals with the cereal starch providing a rapidly fermentable energy source. Such diets, particularly on systems where the feeding frequency is low, may depress rumen pH and promote low rumen volatile fatty acid ratios of acetic + butyric : propionic which are associated with the production of milk of low fat content. The feeding of dairy concentrates based upon materials containing appreciable quantities of digestible fibre may be expected to alleviate this problem. The purpose of the trial reported here was to investigate the effect of concentrate energy source on lactation performance of dairy cows.

30 autumn calving multiparous Friesian cows were fed one of two concentrates which were formulated to isoenergetic extremes of starch and fibre content.

Three weeks before their expected calving date cows were housed in cubicles with access to Calan individual feeders. Following equalised concentrate feeding in a post-parturn covariance period, one of each pair (Pairing having been on the basis of previous milk yield, milk composition and expected calving date) was gradually introduced to its designated concentrate over a five day period. Cows were flat rate fed at 7, 10 or 13 kg concentrate DM/d (depending upon yield potential) from day 20 of lactation for 10 weeks. Concentrates were fed in three equal feeds daily.