With across-flock genetic evaluations, the extent of genetic links or connectedness between animals in separate flocks affects the reliability of selection decisions. As connectedness improves, error in comparing breeding values among flocks falls. Connectedness is thought more important when founder animals (i.e. unknown parentage) of separate flocks differ genetically. The prediction error variance (PEV) of differences in estimated breeding values (EBV) between animals is considered an appropriate measure of connectedness (Kennedy and Trus, 1993). In this study the level of connectedness, and its consequence, in breeding schemes that differ in the extent of ancestral relationships between flocks, and in which founder animals of these flocks differ genetically, was assessed by stochastic simulation.

Currently fewer than 50% of UK lambs produce carcasses of acceptable quality for the domestic and export markets, which compromises the competitiveness of sheep farming. Carcass quality can be changed by selection, and this is now being taken advantage of in terminal sire breeds and, to a lesser extent, in hill breeds. However, little attention has yet been focused on the crossing breeds, which have relatively poor carcass quality, in spite of the large impact such breeds have on the slaughter generation. Recently, a long-term project began to develop breeding programmes relevant to crossing sire (‘longwool’) breeds. Its objective is to produce a selection index to improve carcass quality without compromising the reproductive performance or maternal ability of these breeds. The Bluefaced Leicester is the most prevalent crossing sire breed with its crossbred (‘Mule’) daughters out of draft hill ewes accounting for 89% of crossbred (longwool x hill) ewes in the UK (Pollot, 1998).

Over the last twenty years the British dairy population has undergone a large importation of Holstein genes, largely from North America and Canada. This study aimed to investigate what effect this importation has had on the genetic diversity of the population and also to look at the change in genetic diversity of the population over the last thirty years.

As computing resources did not facilitate sampling of all cows born in the last thirty years, between 4 and 10 random samples of 2000 Holstein-Friesian cows, born every 5 years from 1967 to 1997 inclusive, were taken from the Holstein Friesian Society of Great Britain and Ireland's database. The base population of this database was born about 1960. The complete ancestry of these cows was traced on the database and these sample pedigrees were used for the various analyses.

Dry matter food intake (DMFI) and digestibility (DIG) of the forage are two important nutritional aspects contributing to lambs growth and subsequent meat production. However, there is a lack of literature describing their inheritance and their phenotypic correlations with production traits, e.g. ultrasonic muscle and fat depth and growth rate, in the grazing lamb. This study aimed to investigate and quantify these parameters for grazing lambs.

This study involved 90 male Texel-Oxford lambs in 1995 and 82 in 1996. The sires in 1996 were lambs in 1995, providing genetic links between these two generations. The lambs were split equally between two lines previously selected for increased or decreased carcass lean content. The lambs were born in a five week period in March-April each year, and they were reared on, and grazed, improved mixed- species pasture, typical of a Scottish upland farm.

Few authors have reported on the complete lactation of sheep, without suckling, and most reports deal with ewes under experimental conditions or of non-dairy types (Groenwald et al, 1995; Portolano et al, 1996). In recent years, the commercial Awassi flocks in Israel have weaned their lambs once the lamb has received colostrum from the ewe and so are ideal for studying the complete lactation curves of sheep, under commercial conditions. The objective of this paper is to describe the complete lactation curve of sheep and the factors which affect it.

The records for this analysis were taken from the Improved Awassi flock belonging to the kibbutz Ein Harod. This flock of intensively managed milking sheep has been previously described by Gootwine, Bor, Braw-Tal and Zenou (1995).

Feeding lowland sheep on straw-based systems during pregnancy (Davies and Chapple 1995) has shown that ewe and lamb performance can be satisfactory, providing adequate compound supplementation was fed. Whole barley and soya bean meal has been the standard ration. Experiments with March-lambing ewes (Chapple et al., 1997) has shown that feeds based on molassed sugar beet feed and maize distillers dark grains can replace a barley/soya supplement. The objective of this work was to evaluate the effects on ewe and lamb performance of feeding sugar beet feeds with higher levels of distillers grains to January-lambing ewes on straw-based and big-bale silage systems during pregnancy and early lactation.

Urea is a cheap source of non-protein nitrogen that can be included in ewe diets to meet their increasing demand for protein during late pregnancy. However, its rapid rate of ammonia release results in inefficient utilisation of the nitrogen by rumen microbes. New technology which binds urea with sugar has been developed to reduce the rate of ammonia release (regulated release) in the rumen and increase the efficiency of nitrogen utilisation. The objectives of this work was to evaluate the effects of including a regulated urea release product in the diet of ewes during late pregnancy on ewe and lamb performance.

Fishmeal is a suitable protein source for pregnant and lactating ewes, providing high levels of undegradable protein (UDP) with a high biological value (Sheehan and Hanrahan, 1989). Vegetable protein sources supply a lower proportion of UDP and lack in supply of essential amino acids, but the quality can be improved by heat / chemical treatment and by adding amino acids. It has also been shown that concentrates can be partially replaced by supplementary feed blocks based on soluble sugars and urea with no adverse effects on production and simplifying the feeding regime (Chapple et al, 1996). The objective of the current experiment was to compare the effects of feeding barley based concentrates containing either fishmeal or a protected vegetable protein as the main protein source and the partial replacement of concentrates with a supplementary feed based on soluble sugars and urea (blocks) on the performance and metabolism of pregnant and lactating ewes.

Big bale silage has become increasingly popular on many livestock farms in Ireland yet there is limited information on its use for sheep. The objective of this experiment was to compare the effects of feeding chopped or unchopped big bale silage, pit silage and hay when supplemented with either a barley or a molassed sugar beet pulp based concentrate when fed to ewes in late pregnancy on feed intake, ewe weight and body condition score changes, gestation length, lamb birth weight and colostrum yield.

Sixty four mature lowland cross ewes (8/treatment) were oestrus synchronised in October and mated to terminal sire breeds (Suffolk, Texel or Charollais). The ewes were housed, winter shorn and pregnancy scanned in December, following which twin bearing animals were allocated to a 4 x 2 factorial experiment and individually fed either un-chopped or chopped big bale silage which had been wilted for 36-48 hours as is usual for this type of forage, pit silage, which had been wilted for 18-24 hours or hay.

Maize silage is a popular feed for dairy and beef cattle in the United Kingdom, but its popularity for sheep production has never been great. Several reasons for the lack of interest in maize silage for ewes and lambs have been cited; the growth of an annual crop for silage on holdings with a predominance of long-term leys, the low requirement of ewes and lambs for conserved feed, the possibility of low voluntary DM intakes and the risk of a high degree of selection of dietary components of the diet (Brown and Thomas, 1989). The research reported here examines the use of maize silage for ewes in late pregnancy and early lactation.

Supplementary feeding of hill ewes during pregnancy is an important aspect of sheep management. Two broad groups of feed are given. Firstly, there is feed offered on a restricted basis, daily. Secondly, there are feeds offered on an ad libitum basis, of which feedblocks are the most important form for hill ewes. Some studies have shown interaction between feedblock intake and social behaviour but little is known about foraging behaviour.

The study used three, 3 ha (50m x 600m) paddocks side by side, rising steeply from 280 to 490 metres above sea level on a semi-natural acid grassland hill pasture. Each plot was divided with markers on the fence line into 15 divisions of 40m wide, rising in altitude up the plot, each referred to as grids later. In Plot 1, 10 hill ewes were offered 150 g/head of pelleted molassed sugar beet feed at 10 am each day at grid 1 (i.e. at the bottom of the slope).

In vitro techniques have been developed to study the fermentation kinetics of a wide range of animal feedstuffs but relatively few studies have been conducted specifically with purified feed constituents. This study uses the pressure transducer technique of Theodorou et al (1994) to record cumulative gas production (GP) when six purified starch sources were incubated in vitro.

Three replicates of six commercially available purified (98%) starch sources were incubated in vitro with an inoculum prepared from freshly voided faeces collected from six ponies fed hay ad libitum. The starches were a purified wheat starch (ABRA), four purified wheat starches that had been chemically modified with sodium tri-metaphosphate (V1, V21, V33 & V65) and a purified pea starch (PEA). GP was measured using the pressure transducer technique throughout a 72 h incubation period. At the end of the incubation period DM loss (DML) in vitro was determined by filtration.

Processed cereals are used routinely in diets for equines but little information is available on how physical processing affects the digestibility of cereals in equines. This study examines the effects of three physical processing methods (rolling, micronisation and extrusion) on the in vivo apparent digestibility of barley fed to ponies.

Three mature caecally-fistulated Welsh-cross pony geldings, (LW 284kg ± 3.8kg) were used in a 3 x 4 incomplete latin square changeover design experiment consisting of four 21 day periods. Each period comprised a sixteen day adaptation phase and a five day recording phase when apparent digestibility in vivo was determined. Ponies were offered 4kg dry matter (DM) per day of either 100% hay cubes (HC) or one of three diets consisting of a 50:50 barley:hay cubes mix. The barley in the mixed diets was either rolled barley (RB), micronised barley (MB) or extruded barley (EB). Diets were offered in 2 equal meals per day fed at 09:00 and 17:00 hours respectively.

Maize and peas that have undergone physical processing are used routinely in cereal mixes for equines. However, little information is available on how physical processing of maize and peas affects degradation dynamics in equines. This experiment examines the effect of two physical processing methods (micronisation and extrusion) on in situ degradation of maize and peas in the caecum of ponies

Two caecally-fistulated mature Welsh-cross pony geldings (approx. LW 270kg) were offered ad libitum grass hay plus minerals. Incubation bags (monofilament polyester 6.5 x 20cm, 41? m pores, 16mg/cm2 sample size) containing either unprocessed maize (UM), micronised maize (MM), extruded maize (EM), unprocessed peas (UP), micronised peas (MP) or extruded peas (EP) were incubated in the caecum for fixed times according to both a forward (0, 2, 4, 6, 12, 8, 24, 48h) and reverse (48, 24, 8, 4, 12, 6, 2, 0h) incubation sequence. For each feedstuff residues from each time were bulked within pony and across incubation sequence for subsequent analysis of dry matter (DM) and starch (STC).

Little information is available on how physical processing of cereals affects crude protein (CP) degradation dynamics in equines. In two experiments the effects of two physical processing methods (micronisation and extrusion) on in situ degradation of CP in barley, maize and peas in the caecum of ponies were investigated.

In experiment 1, three caecally-fistulated mature Welsh-cross pony geldings (approx. LW 270kg) were used whilst two of these ponies were used in experiment 2. In both experiments ponies were offered ad libitum grass hay plus minerals. Incubation bags (monofilament polyester, 6.5 x 20cm, 41μm pores, 16mg/cm2 sample size) contained either unprocessed barley (UB), micronised barley (MB) or extruded barley (EB) (experiment 1) and either unprocessed maize (UM), micronised maize (MM), extruded maize (EM), unprocessed peas (UP), micronised peas (MP) or extruded peas (EP) (experiment 2).

Particle size (PS) may be reduced when feeds are ground through small screen sizes leading to increased losses from artificial fibre bags during in situ or mobile bag experiments in equines. Smaller PS may also alter the water holding capacity (WHC) of feeds which in turn may alter bag transit times during mobile bag experiments. This study examines PS and WHC in a range of starch based equine feedstuffs ground through two screen sizes.

Five feedstuffs (F) were used ie: barley (B), maize (M), peas (P), wheat (W) and naked oats (NO). Feedstuffs were subjected to three types of physical pre-processing (Pr) ie: unprocessed (Un), micronised (Mi) or extruded (Ex) and then ground through either a 1.0 or 0.5 mm screen size (SS). For PS analysis a 25g sample of each feedstuff was sieved through a stack of 11 sieves ranging in pore diameter between 45 μm and 2 mm using a mechanical shaker for 20 min.

A wide variety of starch based feeds are available for inclusion in equine diets. These feeds may be subjected to physical processing (micronisation or extrusion) prior to inclusion. This experiment evaluates a range of starch based feedstuffs using an in vitro batch culture technique.

A total of 15 feedstuffs were incubated in vitro with an inocula prepared from freshly voided faeces which was collected from six ponies fed grass hay ad libitum. The feeds were five starch based feedstuffs; i.e: maize (M), peas (P), wheat (W), naked oats (NO) or barley (Ba) in one of three physically processed forms i.e: unprocessed (Unp), micronised (Mic) or extruded (Ext). All feeds were ground through a 1.0mm screen prior to incubation. Cumulative gas production (GP) was measured using the pressure transducer technique of Theodorou et al (1994) throughout a 72 h incubation period.

Previous work has shown that the mobile bag technique (MBT) can be used to study the dynamics of digestive processes in the whole tract of ponies (Hyslop et al, 1998). This experiment further develops the MBT as a method to study feed degradation dynamics over time in the pre-caecal segment of the digestive tract of ponies.

Two caecally-fistulated mature Welsh-cross pony geldings (LW 270kg) were offered 4kg of dry matter (DM) per day of a 1:3 rolled barley:hay cube mix plus minerals, in 2 equal meals per day at 09:00 and 17:00h. Grass hay was also offered ad libitum between 17:00 and 09:00h. Two sizes of mobile bag (6 x 1 cm Ø-large and 4 x 1 cm Ø- small) made from monofilament polyester with a 7 μm pore size were used.

Little information is available on digestion of the non-starch polysaccharide (NSP) fraction of fibrous feeds in equines. Two studies were conducted which examined the in vivo apparent digestibilities of proximate constituents and NSP in ponies offered diets based on botanically diverse fibrous foodstuffs.

In study 1 (S1), three mature caecally-fistulated Welsh-cross pony geldings (266 kg LW) were used in a 3 x 3 latin square changeover design experiment consisting of three 21 day periods. Ponies were offered 4 kg dry matter (DM) per day of either unmolassed sugar beet pulp (USBP), hay cubes (HC) or a 2:1 mix of oat hulls:naked oats (OHNO) plus minerals in 2 equal meals per day. After completion of S1 the same 3 ponies were used in study 2 (S2) where they were offered 4 kg DM/day of a 50:50 mix of USBP:HC (USHC) plus minerals fed as in S1 for a 21 day period.

There is increased interest in using sugar beet pulp (SBP) products as forage replacers in equine diets. Previous work (Hyslop et al 1998) has indicated that SBP products may suppress voluntary feed intake (VFI) in ponies when they are the major fibre source at between 550-700 g/kg total diet dry matter (DM). This study examines VFI and apparent digestibility in vivo where soaked unmolassed sugar beet pulp (USBP) was offered as a partial forage replacement to ponies receiving ad libitum grass hay.

Four mature Welsh-cross pony geldings (280 kg LW s.e. 6.6) were individually housed and offered 0.86 kg/d of micronised barley (MB) and given ad libitum access to grass hay (HAY). In addition, ponies were offered either 0, 1, 2, or 3 kg/d USBP (U0, U1, U2 and U3 respectively) according to a 4 x 4 latin square changeover experimental design.