Correlation among type traits and with milk production has been investigated by Brotherstone (1994) and Misztal et al (1992). One of the primary reasons for collecting and utilizing information on type traits is to aid breeders in selecting profitable functional cows for high production and suitable herd life. The objectives of this study were to estimate phenotypic and genetic correlations among milk production and with udder traits.

Ultrasound technology provides a oportunity to quickly and economically estimate carcass atributes on the live animal (Brethour, 2000). In general, this technology has been used to detect variation for fat depth and ribeye area (longissimus dorsi muscle) in performance tested yearling bulls at several countries. In the present study, real time ultrasonography was used to predict the ribeye area (RA) and the subcutaneous fat thickness (FT) in Nellore crossbred.

Performance recording schemes for sheep flocks in the UK incorporate ultrasonic scanning to measure criteria that are linked to carcass lean content as a selection objective (Simm, 1998). In Wales, under the direction of the Welsh Sheep Strategy, fat and muscle depth has been monitored routinely in hill flocks but with a range of ram ages at scanning (Anderson, 2000; Ap Dewi, unpublished). The date of scanning is often dictated by timings of routine tasks within the flocks so there is a need to explore the impact of time of scanning on the measurements obtained. The objectives of the investigation were to study how muscle and fat depths changed over a series of scanning dates.

The randomly amplified polymorphic DNA technique was developed by Williams et al,(1990) and Welsh and McClelland et al.(1990). The technique is based on polymerase chain reaction using primers homologous to random target sites in the genome. The main advantages of RAPD assays are that it is simple, less labour intensive, comparatively less expensive and safe than other methods. The RAPD hase been used for various applications including species identification, establishing genetic relationships, estimating genetic diversity and genome mapping in various livestock species including sheep. These studies reflected the effectiveness of rapd as potential genetic marker. The objective of the current study was to investigate RAPD marker development to distinguish genetic differences and similarity between and within some Iranian sheep breeds.

Improving breeding values and breeding programs should be done based on genetic potential. The range of additive direct heritability and maternal environment heritability for birth weight is about 0.07 to 0.22 and 0.1 to 0.33 respectively the range of these values for the following weights are 0.09- 0.58 and 0.01- 0.17. the objective of this study was to predict the direct additive genetic effect, maternal genetic effect and heritabilities of lamb weight traits in baluchi breed of sheep.

Sheep growers in Iran who raise breeds with light body weight, most often are interested to use rams of the heavier breeds to inseminate their ewes in order to obtain heavier lambs at sale. However, this practice may or may not be supported with enough scientific evaluations, on which only the results of very few studies are available (Kiyanzad, 2001; Farid, 1991; Makarechian et al 1978). The objective of this work was to declare the growth and feedlot performances of crossbred lambs, resulted from Afshari, Moghani and Shal (three heavy breeds) rams and Varamini (a light breed) ewes. The perfrormance of pure Varamini lambs was also adopted as a comparison benchmark.

The Breeding Center of Raeini (BCR) cashmere goats was established in 1965 in Kerman province, with a base population of 120, 8 and 42 does, bucks, and kids respectively. Some new animals have been introduced to the BCR population in some periods of time, and selected males have been sold out to the local breeders each year. Animals have been selected based on their phenotypic performance for fleece weight (FW) and fleece color (FC-white), and body weight (BW). Mating system has been planned based on non-relative mating, but some relative mating has been occurred. Inbreeding depression is one of the most important empact of having inbreeding in a population (Miglior and Burnside 1995). A decrease of 0.8% in fiber length and 6.3% in longevity per 10% increase of inbreeding coefficient in cashmere goats has been reported (Deb 1998). The objective of this study was to estimate the animals inbreeding coefficient and to explore the impact of inbreeding on some economic traits in Raeini cashmere goats.

Genetic selection has increased pig lean tissue growth rate, the most extreme animals comprising the ‘sire’ lines of breeding stock. However such improvement has not been without cost in other areas of production. Sire line sows are characterised by smaller litters with poorer pre-weaning growth rates than dam line sows of the same breed. The aim of this experiment was to determine whether reduced pre-weaning growth rate of sire line piglets was due to poor lactation performance of the sow or reduced vitality of sire line piglets.

Thawed rumen contents have been used to obtain strained rumen fluid (SRF) to estimate in vitro dry matter degradation (DMD) of feeds (Mohamed et al., 2002). However, thawed SRF (TSRF) gave lower DMD than fresh SRF (FSRF) which was partly attributed to reduced microbial activity in TRSF following storage at -20°C. This study examined the addition of glycerol (G) as cryopreservative and washing from particle associated microbes to SRF before its storage for later use as TSRF to estimate in vitro degradation of rapeseed meal (Rsd) and grass nut (Gnt).

The use of faecal inoculum in in vitro feed evaluation methods was examined by Balfe (1985). However, there is limited information concerning the chemical composition of faeces and factors affecting this. The chemical composition of faeces may reflect the microbial population and hence its fermentative activity. A knowledge of the faecal composition is essential as this affects the quality of faecal inoculum. The objective of this work was therefore to study the relationships between diet and the chemical composition of faeces using data obtained from sheep.

Rumen microbes contain a high proportion (20 to 50%) of their fatty acids (FA) as odd and branched chain fatty acids (OBCFA; C15:0, iso C15:0, anteiso C15:0, C17:0; iso C17:0; anteiso C17:0 and C17:1) and different bacterial classes have distinctive OBCFA ‘fingerprints’. As OBCFA make up around 5% of FA in milk, it has been suggested that there is scope for these compounds to be used in on-farm diagnostic milk-based tests in relation to the rumen fermentation pattern. Correlations of milk OBCFA with rumen fermentation pattern were recently shown (Vlaeminck et al., 2002). In the current in vitro study, the potential of rumen OBCFA to predict the production of volatile fatty acids (VFA) was evaluated.

Whole–plant maize silage dorms the basis of winter rations for the vast majority of dairy and beef cattle production in Uruguay. Microbiological examination of silage is of little value in gauging the outcome of silage, and so chemical analysis is more reliable and meaningful indicator of quality. Chemical assessments of the principal fermentation products provide an unequivocal basis on which to judge quality. Silage fermentation and chemical composition are important to preservation of forage with respect of feeding value and animal performance. Many of the important chemical components of silage must be assayed in fresh (wet presentation) or by extraction of the fresh material, since drying either by heat or lyophilisation, volatilises components such as acids or nitrogenous components, or effects conversion to other compounds (fibre and carbohydrates) (Abrams et al., 1987). Chemical and biological methods for assess maize silage quality are laborious and considered to slow to be used for routine analysis of large number of forage samples. Near infrared reflectance spectroscopy (NIRS) is increasingly used as a rapid, accurate method of evaluating chemical constituents in cereals and dried forages. The objective of this study was to determine the potential of NIRS to assess the chemical composition of dried maize silage samples for advisory purposes.

It is not possible to carry out in vivo pig digestibility studies on each feed or feed ingredient therefore there is a need for a rapid means of predicting the digestible energy content of a feed or feed ingredient. Near infrared reflectance spectroscopy (NIRS) is an extremely rapid technique and has been used to predict chemical composition and nutritive value for a wide range of feeds and feed ingredients (Leeson et al 2000). In the literature, some workers have reported that NIRS has a high degree of accuracy for determining chemical composition and nutritive value while others have reported a lower degree of accuracy. The aim of the current study was to examine the value of NIRS in predicting the digestible energy (DE) content of barley from which pig diets were formulated.

The nutritive value of forage crops is related mainly to climatic conditions and stage of plant maturity, and its determination for any given crop is essential for optimum planning and animal feeding (Berardo et al., 1993; Deaville and Flinn, 2000). Worldwide the nutritive value of forages is often estimated by chemical or physical methods and is expressed as the concentration of chemical constituents in the plant tissue. There is little information in the literature about the use of NIRS to determine degradability in pastures with different conditions, season, different places (Wilman et al., 2000). The aim of the work to explore the use of NIRS as rapid tool for estimate DM and N degradability in forages.

Few methods exist for quantitatively estimating the diet composition of free-ranging herbivores. Because their patterns differ between species, plant n-alkanes have been successfully used as faecal markers to estimate the botanical composition of simple diets, however, the reliability of this methods may decline as the number of dietary plant species increases (Dove and Mayes, 1996). The objective of this study was to examine whether additional plant-wax compounds, such as long-chain fatty alcohols (Alc) or long–chain fatty acids (Ac) could be used along with n-alkanes (Alk) to allow reliable diet composition estimates to be made in herbivores consuming complex diets.

In the Basque country and Galicia conditions, forage is usually conserved as silage, which accounts for a great part of cows winter rations. Robust techniques that predict the quality of forages for developing improved feeding strategies and screening of large number of forage samples are needed. In this sense, the gas production technique has proved to be of great interest when considering hays (Khazaal et al., 1995) and grass (Chenost et al., 2001), but information concerning grass silage in vivo data and gas production parameters is scarce. Therefore, the objective of this work is to try to assess in vivo grass silage apparent digestibility by means of gas production parameters.

The in vivo determination of methane (CH4) production requires specialist equipment which is costly to maintain. Whilst the in vitro gas production technique has been demonstrated to show potential to rank diets for their methanongenic potential at maintenance planes of nutrition (Moss and Givens, 1997) no study has investigated this relationship when feedstuffs are fed ad libitum. The objective of this study was to assess the ability of the technique to predict in vivo CH4 production and animal performance from six diets differing in their chemical composition.

Previous studies have identified small but significant differences in in vitro methane (CH4) production between perennial ryegrass cultivars harvested pre-heading date. This raises the possibility that enteric CH4 production could be reduced through cultivar selection. The aim of this study was to assess the effect of harvest date on in vitro CH4 output of two cultivars previously identified as having a high and low methanogenic potential (Lovett et al., 2003).

Stable isotopes have been extraordinarily helpful in understanding animal migration, diet, food webs and nutrient flow (Hilderbrand et al., 1996), based on the property that C3 and C4 plants possess distinctly different 13C/12C ratios (δ13C value) due to isotopic fractionation during photosynthetic carbon fixation (Smith & Epstein, 1971). Most woody species and temperate graminoids assimilate carbon via the Calvin cycle (C3), which discriminates stronger against the heavier isotope (13C) than Hatch-Slack (C4) species (tropical and subtropical graminoids and some shrubs). C3 and C4 plant species have mean δ13C values of -27 ‰ and -13 ‰ respectively (O’Leary, 1981). DeNiro & Epstein (1978) were one of the first to show that the isotopic composition of the whole animal body is similar to that of its diet. Other authors have also found relationships between the isotopic composition of animal tissues and the diet (González-Martin et al., 1999; Jones et al., 1979). The aim of this study was to investigate stable carbon isotope composition in sheep fed diets consisting of either C3 or C3+C4 plants.

Non-degradable dietetic protein supply depends on rumen degradation. Determination of microbial protein synthesized in the rumen as the result of microbial fermentation is important because microbial protein synthesis could be influenced by diet (Dove and Milne, 1994). Several evaluation systems consider the contribution of microbial protein on protein intestinal flow as a constant, based on feed intake. But this approach has presented great variations. The purpose of this work was to determine in vivo microbial protein kinetics for sheep fed with three protein level hays.