The final goal in the most animal breeding programs is increasing of producing ability of the animals. Measuring the GCA and SCA for selecting the superior parents is important. 3-7 additive genes play more important role in the inheritance of some economical characters. Investigation on GCA and SCA of production and reproduction parameters has been showed that amount of SCA is more than that of GCA. Parents' possessing high GCA are generally considered for population development and for initiation of pedigree breeding as it is heritable and can be fixed. SCA consists of nonadditive, dominant effects and other interactions (Ravindra et al, 2003). Since these value are not constant in different regions, thus must be estimated in different countries.

Silkworm is an important industrial insect with many unique characters. Combining ability of parents at animals and silkworm is dependent on different genetic effects that cannot be analyzed completely with phenotype performance. Many reports have showed that many good characters at silkworm have heterotic effects (Rajanna and Puttaraju, 1998). In Sericulture, the parents with high general combining ability are used generally for improvement of silkworm population performance. These parents considering additive effects and additive×additive effects produce high heterosis. Meanwhile the special combining ability includes non-additive effects, dominant effects and other genetic effects (Singh et. al. 1990). Double cocoons have two pupae together in one cocoon. These cocoons are an important section of production by silkworm. Therefore, analysis of combining ability for double cocoon character is beneficial for understanding of its genetic specifications and improvement of production level.

The silkworm is an important industrial insect and like the other species needs proper adopted rearing conditions according to its physiological requirements to fulfil desirable performance. Since most of the farmers at different provinces of Iran use traditional rearing systems which will be affected by their regional climate conditions, it is necessary to evaluate the performances of Iranian commercial silkworm hybrids at different rearing conditions. Elena (2002) studied and confirmed the effects of different microclimate conditions on the depression of silkworm performance. Guar and Upadhyay (2003) demonstrated the effects of ecological changes on the amino acid content of the silk gland in silkworm larvae. The silkworm hybrid of 151×154 is the most recently introduced commercial hybrid in Iran and the objective of this study is to evaluate its performance at different microclimate conditions which will help to identify the proper regions for this hybrid.

The general aim of selection in animal breeding is to acquire new generation of animals, which under future economic conditions of production system are more efficient than the present generation (Groen, 1990). Economic values are functions of incomes and expenses of a production system and changes in these factors may result in changing economic values. Estimates for the economic values depend on the definition of the production system, the goals to be optimized and particular production circumstances. Production systems can be optimized to different goals, e.g. maximum profit, minimal costs of product or maximum return on investment. Circumstances that limit input or output, e.g. a quota system for production or environmental legislation, might affect the economic value of a trait. This study focuses on the derivation of economic values based on a cost to return function for Iranian commercial silkworm lines and effect of different perspectives on economic values.

The primary goal of silkworm breeding programs is gathering the desirable genes in appropriate combinations for improving genetic performance to maximize the yield and productivity per animal (Kang et al., 2003). The general aim of selection in animal breeding is to acquire new generation of animals, which under future economic conditions of production system are more efficient than the present generation. In multiple-trait selection by means of selection index method, it is necessary to evaluate economic values of traits. In this method, genetic trend of important traits is directed based on their weights in economic efficiency of production system to acquire maximum improvement in economic merit (Mirhosseini et al., 2005). The objective of this study was to estimate genetic parameters, additive genetic values and economic values of cocoon traits to design selection index program and evaluate genetic-economic responses to index selection.

White tailed deer is distributed along America. In Yucatán, México, the sub specie O. virginianus yucatanenses was been hunted for food, leather and ritual purposes in prehispanic times. The yucatecan native white tailed deer (O. virginianus yucatanensis ) is considered an endangered sub specie due to severe hunting practices. The establishment of farms (governmentally approved) has been encouraged in recent years in order to alleviate the pressure upon its numbers in the wild. However, most of the incipient farms are been set without adequate knowledge of deer biology. In order to establish proper management practices it is necessary to gather information of deer biology including the forage feed preference, intake and digestibility. Thus, the objective of the present work was to evaluate white tailed deer preference, intake and digestibility of four forage trees.

The continuing need of protein sources for the human population aside of the economic world is of considerable social interest, so the rational use of the local fauna has both economic and social advantages, while protecting wild species from extinction through irrational hunting and habitat destruction. Among Brazilian mammals the capybara is a big rodent, with high reproductive potential, are herbivorous, they increase their digestive efficiency through extensive mastication followed by fermentation by cellulolitic bacteria and protozoa in the cecum (González-Jiménez, 1995). Furthermore, capybaras are able to use microbial protein from the cecum after fermentation through the cecotrophy, or ‘reingestion’ of the cecal content (Mendes et al., 2000). In function of the controversial findings regarding cecotrophy in capybaras, this study was conducted to compare the faecal excretion curves of capybara, collared peccary (Tayassu tajacu) - animal that does not accomplish the cecotrophy, and rabbit (Oryctolagus cuniculus) - animal that accomplishes the cecotrophy.

The breakdown of immunity to parasites during the periparturient period plays an important role in parasite epidemiology and it is believed that it has a nutritional basis. A lactating rat model has been used to address this issue, as their nutritional status can be easily manipulated through altering greatly supply and demand and they exhibit a breakdown of immunity to the gastrointestinal nematode, Nippostrongylus brasiliensis. Previous experiments have shown that an increasing protein supply and reducing protein demand improves resistance (Houdijk et al., 2005; Normanton et al., 2005). However, in these studies, an increase in protein contents was associated with an increase in feed intake per se. Therefore, effects of protein supply could be confounded with effects of any nutrient or energy intake. The objective of the current experiment was to test the effect of increased protein supply or reduced protein demand on the resistance to parasites in lactating rats whilst energy intake was kept constant.

The grazing of ducks in carp feeding ponds is a profitable proposition. Ducks droppings are valuable organic manure; 100 kg of duck excreta contains 0.8 kg nitrogen, 1.5 kg phosphorus, and 0.4 kg potassium (Martyshev 1983). Woynarovich (1979) reviewed the practice of growing ducks and fish together. He calculated that one duck produces 6 kg of droppings during a 30-40 d period. At least 500 ducks can be kept on 1 ha of pond for a year, which corresponds to 36000 kgha-1 of duck manure. Also, he estimated that each 100 kg of duck manure, distributed continuously in pond water, might result in an increase of 4 to 6 kg of fish flesh. The aim of this study was to assess the fish production performance between two ponds (with and without duck).

Farming systems in Botswana can be divided into two, subsistence and commercial. Most livestock producers are smallholder farmers, who do not have concentrate feedstuffs that could be used for supplementation during the extended dry seasons. Browse plants in genera Acacia, Boscia, Combretum, Grewia are valuable resources for smallholder farmers because they are rich in proteins and minerals (Aganga et al., 2001). However there are some browse plants that have anti nutritional chemicals e.g. tannins, which decrease availability of protein. Some are known to have medicinal properties for example Acacia trees. Farmer’s knowledge has been there for a long time, and this research aims at finding out what oral tradition knows that has never been documented. The bank of indigenous knowledge in livestock and local feed resources such as browses when harnessed, adapted and utilized can improve the lives of local communities. The objectives of this study is to document Kweneng farmer’s knowledge of browses species fed to livestock.

A study reported by Magowan et al. (2006) determined a large variation in growth rate, between herds of pigs in Northern Ireland reaching a live weight of 100 kg, equating to an average difference of 18 days. All pigs used in the study were of the Landrace x Large White breed. It was considered that the large variation in growth rate was mainly a result of different management or disease levels. It was therefore hypothesised that, if a representative sample of pigs from the various sources were housed in a common environment, performance of the pigs would be similar. The aim of this work was to investigate the variation in the performance of pigs sourced from herds with varying growth performance and housed in a common environment.

Variation in pig performance is common within and between herds. Between herds, this variation may occur as a result of different management and nutritional regimes (Bruininx et al., 2002), disease levels or genetics (Kennedy, 1984). However, the extent of this variation and its subsequent effect on the profitability of a pig unit has not yet been quantified. The aim of this work was to investigate the variation in growth performance of pigs from different herds within Northern Ireland and estimate its impact on profitability.

During the last 15 years, analytical methods (inmunological and enzymatic procedures) have been focused on the identification of meat species in raw, cooked and processed products. Near infrared reflectance (NIR) spectroscopy methods are attractive options due to the speed of analysis and minimal sample preparation. NIR spectroscopy has emerged in the last 30 years as a rapid method for testing the quality of intact samples from the light they reflect. One of the advantages of NIR technology is not only to assess chemical structures through the analysis of the molecular bonds in the near infrared spectrum, but also to build a characteristic spectrum that represents the “finger print” of the sample. The Pampa-Rocha breed of pig is originated from Uruguay and it has been a zootechnic resource related to medium to small farm production systems. The objective this study was to evaluate the potential use of visible (Vis) and near infrared reflectance (NIR) spectroscopy combined with chemometrics to identify and trace muscles from autochthonous breed of pig (Pampa-Rocha) and commercial cross (Pampa x Duroc) from Uruguay.

In sows, excessive loss of live weight and body tissue reserves during lactation is associated with reduced subsequent reproductive performance. This is a particular problem in the gilt where the combination of low feed intake potential and relatively low body fat reserves often results in large amounts of body tissue catabolism during lactation to support milk production. The key to minimizing weight loss during lactation is to maximize feed intake of the gilt during lactation. Although there has been a substantial amount of research in this area, most of this has been carried out in research facilities. The objective of this research was to investigate the impact of feeding strategy (i.e., method and frequency of feeding) on feed intake in gilts during lactation under commercial conditions.

The routine inclusion of in-feed antimicrobial growth promoters (AGPs) have long been used to improve performance and to protect against enteric disorders in newly weaned pigs (Hampson, 1994). However, due to increasing concerns about their use in pig production, they are being phased out within the EU. This will put the weaner pig at greater risk to post weaning enteric disorders such as post weaning colibacillosis (PWC), and accentuate the need for alternative, non-pharmaceutical, strategies for disease prevention. These strategies may include the manipulation of dietary protein supply, in order to minimise protein availability to intestinal microflora including enterotoxigenic E. coli (ETEC). The objective of the current experiment was to investigate the effects of dietary protein availability to intestinal microflora through manipulating protein quantity and/or quality on the health and performance of newly weaned pigs in the absence of AGPs when experimentally challenged with ETEC.

When emptying finishing barns, it is common practice on U.S. operations to dispatch pigs over a two- to three-week period with the heaviest animals being selected first. However, there has been little research carried out under commercial conditions on the effect of removing different proportion of slaughter weight pigs from a pen on the subsequent growth performance of the remaining pigs. This study was carried out to investigate the effect of removing 0 to 45% of the heaviest animals from a pen on subsequent pig performance at slaughter.

Low feed intake after weanimg is common, in which case it is recommended that concentrations of nutrients, such as lysine and energy by increased. Lysine is the first limithing aminoacid in most diets used for maximizing protein accretion during pig growth. A fundamental factor that determines protein depositionis the content of metabolizable energy (ME) which is need for protein anabolism. It is convenient that the dietetic energy and lysine (LYS) contents supply the requirements for maintenance and body mass accretion, according to specificities involved in modern pig production. The purpose of the present study was to investigate the effect of ME and digestible LYS levels on the performance and nitrogen (N) retention of piglets during the initial-1 phase and subsequent effects during the initial-2 phase.

The piglet is susceptible to digestive upsets associated with the post-weaning growth check. To minimise this, heat treatment of cereals is used to cereal starch by reducing crystalinity, thereby increasing digestibility and dietary energy-yielding value (Lawrence, 1973a). However, benefits from heat treating are difficult to compare due to the number of processing variables used and, often, a failure to declare variables. Two trials were designed using controlled variables to assess the effect of heat processing (through micronisation and extrusion) on wheat nutritional value, and to determine whether responses to processing are affected by endosperm texture.

The newly weaned pig has a limited capacity to secrete acid, which acts as a natural barrier against bacteria and activates pepsinogens (Kidder and Manners, 1978). We hypothesised that more acidic stomach conditions could be created by adding organic acid to the diet or by replacing inorganic phosphate, in the form of dicalcium phosphate, with phytase. The addition of formic acid to the diets of growing pigs has been shown to increase growth rate and feed conversion ratio. This effect was greater when supplementary phytase was also added to the diets, Jongbloed et.al (2000).

Wheat and barley are common ingredients in diets for growing and finishing pigs. Traditionally, barley has been included at higher inclusion levels due to a lower purchase cost and also because of reports that high levels of wheat inclusions (700g/kg) can cause stomach ulceration (Nielson and Ingvartsen 2000) and pig grading problems (Hanrahan and O’Grady 1984). However, wheat contains a higher digestible energy (DE) content than barley (15.2 vs. 13.9 MJ/kg DM) and therefore substituting wheat for barley should result in better pig performance (Van Barneveld 1999). The aim of the study was to investigate the effect of increasing the level of wheat in growing/finishing pig rations on performance and stomach ulceration.