Exiting is a complex issue, and many factors are involved in the decision to exit a cow. Farmer consider many cow factors, such as age, stage of lactation, milk production, health status, disposition, and reproductive performance, when determining whether or not a cow should be exited (Beaudeau et al., 2000). The exiting decision may also be affected by economic factors, such as milk price, the price of exited cows, and the price and availability of replacement heifers. In addition, the attitudes of farmers have an effect on which cows are removed from a herd (Bascom and Young, 1998). Iranian dairy production has undergone significant and considerable structural changes during the last two decades with creation of larger herds. Replacement of dairy cows is a major expense for producers. To keep a cow until a higher parity allows the farmer to spread over a longer period the difference between the production cost of the replacement heifer and the carcass value of the exited cow (Seegers et al., 1998). In Iran, the increased price for replacement heifer in the last several years has increased the interest in increasing productive life and there by lowering exiting rates. Analyses of the reason of exiting are needed to predict herd performance and maximizing herd profit. The objective of this study was to study the reasons for exiting in Iranian Holstein cows.

Exiting is the departure of cows from the herd for several reasons. Cows are exited for a variety of reasons. The predominant reasons for exiting are reproduction (i.e., failure to conceive), health, and low production (Bascom and Young, 1998). Half of the herd removals occur involuntarily and prematurely because of health disorders (Beaudeau et al., 2000). On the other hand, the risk of exiting is not consistent across all stages of lactation. Cows experience the highest risk shortly after calving (Fetrow et al., 2006). Cow longevity is highly related to dairy farm profit. Only a few previous studies have characterized exited cows based on the associations between exiting reasons and cow economic characteristic. One of this important characteristic is the lactation stage when the cow is exited. There is, therefore, a need to evaluate the overall exiting reasons and the stage of lactation the cows exited the herd. The objective of this study was to study the days in milk at exiting in Iranian Holstein dairy cows.

Urinary nitrogen (N) is rapidly converted to ammonia (NH3) during manure collection and storage, whereas faecal N is converted to NH3 at a much slower rate. Developing nutritional strategies to shift N excretion from urine to faeces may reduce NH3 from dairy manure which is implicated in reduced air quality. Previous work suggests that increasing post-ruminal fermentation may reduce urinary N and consequently manure NH3 losses (Gressley and Armentano, 2005). Pectin is a class of neutral detergent-soluble fibre (NDSF) and studies in monogastrics have shown that it is completely degraded by resident intestinal bacteria (Buchanan et al., 1994). Gut bacteria are capable of converting blood urea-N into NH3 and subsequently microbial protein. Therefore, growth of intestinal microorganisms using energy supplied by pectin can result in a net conversion of blood urea N into faecal microbial N, thereby reducing urinary N. The aim was to determine the effect of increasing carbohydrate fermentation in the large intestine on urinary N in lactating dairy goats.

It is a general believe that the local sheep breed Churra da Terra Quente (CTQ), reared in the Northeast of Portugal is well adapted to the conditions of its production system. However, there are large gaps on our knowledge to allow understanding of such claimed adaptation. Several researchers have found differences in digestibility between sheep breeds (e.g. Givens and Moss, 1994; López et al., 2001), suggesting that those fed natural resources can have an improved ability to digest fibre. This experiment was designed to compare digestibility coefficients of a high– and a low–roughage diet measured on sheep from CTQ and Ile-de-France (IF) breeds at the same degree of maturity.

The over-dependency and misuse of the chemotherapeutic drugs available to parasite control with consequent development of anthelmintic resistance, mainly in small ruminants, has been demanded alternative sources to control gastrointestinal nematodes in sheep. The aim of the present study was to investigate the potential anthelmintic effects of condensed tannins (CT) from acacia extract (AE) on Trichostrongylus colubriformis in experimentally infected sheep.

Phosphorus (P) is an essential nutrient in livestock production, involved in most metabolic processes in the body, and with an impact on bone development and growth. Diet supplementation with P can improve productivity, but at excess levels the P utilization can be low, and the high P excretion will lead to environmental pollution (Tamminga, 2003). P supplementation also adds substantially to the cost of feed. Using the isotopic dilution technique (Vitti et al., 2000), we have studied the effect of different P levels in diet on P absorption and excretion in Brazilian sheep, and identified the level at which true P absorption saturates.

Seasonal wool production which is under some genetic performance appears to be largely responsible for variation in staple strength, fibre diameter and its confidence of variation (Butler, 1994). Baluchi sheep breed live in central and eastern parts of Iran under different altitude and weather with diverse conditions. This breed comprises 19 per cent of Iranian sheep population and its fibres known as a good quality of carpet wool. This study aimed to evaluate the seasonal effects on native wool which improving wool traits by nutritional strategy on adverse time.

Early finished lambs are able to command a higher premium at slaughter. Improvement in growth rate can increase the profitability of the enterprise. The use of yeast cell wall preparations, in particular the mannan oligosaccharide portion, has been shown to improve intestinal tract health and thus growth rates in other species (Uni & Smirnov, 2006; Rosen, 2006). Farm studies have suggested that the inclusion of mannan oligosaccharides have the greatest effect in young animals prior to weaning. The aim of the current study was to determine the effect of feeding a mannan oligosaccharide on the growth rates of early finished lambs reared indoors on a commercial farm from birth until weaning.

Alterations of foetal development in utero can affect the structure and physiology of the adult offspring, a process known as “foetal programming” (Barker, 1994). Results from the first phase of this study indicated that offspring from mature ewes offered a restricted energy intake in early pregnancy were heavier at birth and had improved survival rates to weaning (Muñoz et al., 2006). The aim of the second phase of the study was to determine the effects of plane of ewe nutrition in early and mid pregnancy on carcass characteristics of male offspring and on reproductive performance and concentrations of the adiposity indicator, leptin, in female offspring, post-weaning.

High producing dairy cows are often fed large quantities of high quality proteins, and because ruminal protein degradation is not directly coupled to microbial protein synthesis, ruminal NH3-N production is always excessive and ultimately lost by urinary N excretion. Increasing the supply of ruminally fermentable carbohydrates can reduce ruminal ammonia-N concentration and increase milk protein yield (Sannes et al., 2002). The addition of sugar has increased ruminal and whole animal N efficiency in sheep and steers, reportedly to a greater extent than starch (Chamberlain et al., 1993). The objective of this work was to investigate the effect of diets containing different non fibre carbohydrates (NFC, sucrose or starch) on ruminal pH and ammonia-N concentration in Holstein steers.

The availability of nutrients in low concentration in diets is difficult to be accessed by means of experiments like apparent digestibility assays. That is because the endogenous contribution underestimates the true availability. The best tool to study the true availability of minerals is the in vivo isotopic dilution technique. Phosphorus (P) and calcium (Ca) are the most studied minerals due to their great importance in animal nutrition. P is one of the most polluting nutrients because of high husbandry concentrations in restricted areas (Tamminga, 1992). There are some remaining doubts concerning the true digestibility of phosphorus. The present study compiles data from previous studies dealing with true availability of different P sources in beef cattle to estimate pollution potential of animal excretions.

With the continued expansion of livestock units in the UK there is often an increased number of cattle reared per stockperson. Artificially reared calves are predominantly fed milk twice per day to weaning at 5 to 9 weeks old. Rearing systems that reduce the amount of labour reared per calf yet maintain animal welfare and performance standards therefore merit evaluation. The objective of this experiment was to evaluate the effect of rearing dairy-bred beef calves on either a once or twice a day milk feeding system to weaning at 6 weeks old.

Rumen pH, together with the microbial population, nature of substrates, environmental factors such as temperature and existence of cations and soluble carbohydrates have been suggested as factors governing bacterial attachment to ingested feed particles (Miron et al., 2001). Ruminal pH is one of the most important of these factors, because fibrolytic bacteria are very sensitive to pH change. Fibre digestion decreases at low rumen pH, especially below pH 6.0, as observed previously in studies using continuous cultures of mixed ruminal micro organisms, in vitro rumen, and in situ techniques. The objective of the present experiment was to investigate the effect of fluctuation in rumen pH on the attachment of Ruminococcus flavefaciens to feed particles incubated in the rumen.

The complex symbiotic microbiota in the rumen is responsible for the enzymatic breakdown of plant fibres, an ability the ruminant host animal lacks. This microbiota is highly responsive to changes in diet, age, antibiotic use, and the health of the host animal, and varies according to geographical location, season, and feeding regimen. Fibrobacter succinogenes and Ruminococcus flavefaciens are considered to be the predominant cellulolytic bacteria present in the rumen (Krause et al., 2003). Ruminal pH fluctuates considerably in a 24h period and is influenced by the intake of fermentable carbohydrate, the inherent capacity of the animal to produce saliva, and rates of utiliszation and absorption of acids. In beef cattle fed high-concentrate diets, the ability of the animal to buffer the rumen is limited by inadequate salivary secretion. The objective of the present experiment was to investigate the effect of fluctuation in ruminal pH on the population of F. succinogenes in rumen fluid.

Parasitic disease remains a major problem to livestock across all production areas of Nepal. 24% of deaths in sheep were reported to be due to internal parasites (Shrestha et al 1988) and total economic losses were reported to be about 25% (Lohani and Rasali 1995). The main way of controlling nematode parasite of sheep and goat has been with the use of chemical anthelmintics. However, poor and uneducated farmers are unaware of this method and synthetic anthelmintics are not readily available in the rural village. Moreover, these drugs are very costly. Ethnic people in Nepal are using several plants as medicine. Thus, the aim of the present study was to validate scientifically the use of Artemisia species as anthelmentic against the nematode of sheep.

In Northeast of Portugal sheep is reared under extensive systems. These systems frequently involve expressive body composition changes due to the storing and mobilization of body reserves, mainly fat. Body condition score (BCS) is the most common way to assess these reserves and the nutritional status of ewes. However due to the subjective nature of BCS, their quality has been questioned and other alternatives has been studied. For cattle there are some studies that use the real time ultrasonography (RTU) to evaluate the BCS (Schwager-Suter et al., 2000; Broring et al., 2003), but this approach was not tested in ewes. Therefore the aim of the present study was to establish a relationship between the BCS and ultrasound subcutaneous fat (SF) and Longissimus thoracis et lumborum muscle (LM) measurements.

In Portugal consumers prefer low weight carcasses from kids. Some studies on carcass and meat characteristics were conducted with this type of carcasses (Santos et al., 2007). However, there is little information on the effect of increasing the live weight at slaughter by supplementing the diets fed to kids with concentrate in order to maximize meat production. The objective of this study was to evaluate the effect of diet, sex and degree of maturity of kids from Serrana breed on carcass composition and in muscle chemical composition.

Footrot is the main cause of lameness that adversely affects the welfare and productivity of sheep so measures to control it will bring both economic and welfare benefits. The use of breeding strategies to manage footrot is a cumulative and sustainable solution that may contribute to its control. As part of a research programme to investigate genetic resistance to footrot, the aim of this paper is to assess the usefulness of foot score categories to quantify footrot in sheep, to identify key environmental factors that affect footrot and to assess the repeatability of different foot scorers on separate scoring occasions.

Mastitis has been one of the major diseases in dairy herds inducing economic costs associated with decreasing milk yield and its quality as well as increasing health care practices. In response to bacterial infection, the concentration of somatic cells increases in the milk of dairy cows (Boettcher et al., 2007). Somatic cell count has been widely utilised as an indicator trait for mastitis. Somatic cell count, like milk yield, varies with stage of lactation and more accurate genetic evaluation of dairy cows could be obtained when a test day model is used (Haile-Mariam et al., 2001). The main aim of this research was to compare fixed and random regression test day models in genetic evaluation of Iranian Holstein first lactation cows based on their predicted breeding value for somatic cell score.

Silkworm is an important industrial insect with many unique characters. Many reports showed that many traits in silkworm have heterotic effects (Rajanna and Puttaraju, 1998). Newly evolved silkworm lines and hybrids need to estimate these effects (Kumar et al. 1994). The use of selection for genetic and economic improvement of traits in the shortest time will have the highest improvement. To date, selection of parental generations for silkworm egg production in next generation, based on phenotypic characterizations without individual records. Although reproduction and production traits record individually has expensive costs, however it expected selection based on individual records can improve offspring performance, especially if these economical traits have relatively high heritability. There are three Chinese pure and commercial lines at Iran. Since these lines have different phenotypic and genotypic characterizations, thus their response to individual selection system can be different. Therefore, in this experiment the effect of selection on reproductive characters on Chinese lines during three years was investigated.