(1991). Applied Linear Regression Models. Journal of Quality Technology: Vol. 23, No. 1, pp. 76-77.

Applied Linear Regression Models

The goal of this review was to analyze published data related to mitigation of enteric methane (CH 4 ) emissions from ruminant animals to document the most effective and sustainable strategies. Increas- ing forage digestibility and digestible forage intake was one of the major recommended CH 4 mitigation practices. Although responses vary, CH 4 emissions can be reduced when corn silage replaces grass silage in the diet. Feeding legume silages could also lower CH 4 emissions compared to grass silage due to their lower fiber concentration. Dietary lipids can be effec- tive in reducing CH 4 emissions, but their applicabil- ity will depend on effects on feed intake, fiber digest- ibility, production, and milk composition. Inclusion of concentrate feeds in the diet of ruminants will likely decrease CH 4 emission intensity (Ei; CH 4 per unit animal product), particularly when inclusion is above 40% of dietary dry matter and rumen function is not impaired. Supplementation of diets containing medium to poor quality forages with small amounts of concen- trate feed will typically decrease CH 4 Ei. Nitrates show promise as CH 4 mitigation agents, but more studies are needed to fully understand their impact on whole-farm greenhouse gas emissions, animal productivity, and animal health. Through their effect on feed efficiency and rumen stoichiometry, ionophores are likely to have a moderate CH 4 mitigating effect in ruminants fed high-grain or mixed grain-forage diets. Tannins may also reduce CH 4 emissions although in some situations intake and milk production may be compromised. Some direct-fed microbials, such as yeast-based products, might have a moderate CH 4 -mitigating effect through increasing animal productivity and feed efficiency, but the effect is likely to be inconsistent. Vaccines against rumen archaea may offer mitigation opportunities in the future although the extent of CH 4 reduction is like- ly to be small and adaptation by ruminal microbes and persistence of the effect is unknown. Overall, improv- ing forage quality and the overall efficiency of dietary nutrient use is an effective way of decreasing CH 4 Ei. Several feed supplements have a potential to reduce CH 4 emission from ruminants although their long-term effect has not been well established and some are toxic or may not be economically feasible.

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Special topics--Mitigation of methane and nitrous oxide emissions from animal operations: I. A review of enteric methane mitigation options.

This review summarizes information regarding digestion and absorption of carbohydrates in cultivated fish Relevant results of studies of digestive enzymes, eg amylase, chitinase, cellulase and brush border disaccharidases are presented Fish amylases appear to be molecularly closely related and to have characteristics comparable to mammalian amylases Whether chitinases and cellulases are endogenous enzymes of some fish species is still a matter of speculation, although recent molecular evidence, at least for chitinase seems to settle the issue in favour of endogenous sources Feed and intestinal microbes may be the source of polysaccharidases in fish feeding on nutrients-containing non-starch polysaccharides Knowledge regarding monosaccharide transport in fish intestine as interpreted from studies of brush border membrane vesicles, everted sleeves of fish intestinal sections and molecular biology is discussed Glucose transporters of the intestinal brush border show characteristics similar to those found in mammals A tabulatory presentation of experimental details and results reported in the literature regarding starch digestibility is included as a basis for discussion Although numerous investigations on digestion of starch and other carbohydrates in fish have been published, the existing information is highly fragmentary As yet, it is impossible to derive a cohesive picture on the integrated process of carbohydrate hydrolysis and absorption and interaction with diet composition for any of the fish species under cultivation The physiological mechanisms behind the species differences are not known

Carbohydrates in fish nutrition: digestion and absorption in postlarval stages

Publisher Summary
This chapter discusses the amino acids and protein requirements of fish. Proteins are the major organic material in fish tissue, making up about 65–75% of the total on a dry-weight basis. Fish consume protein to obtain amino acids. A regular intake of protein or amino acids is required because amino acids are used continually by the fish, either to build new proteins (as during growth and reproduction) or to replace existing proteins (maintenance). Inadequate protein in the diet results in a reduction or cessation of growth and a loss of weight due to withdrawal of protein from less vital tissues to maintain the functions of more vital tissues. Fish, like other animals, do not have a true protein requirement but have a requirement for a well-balanced mixture of essential or indispensable and nonessential or dispensable amino acids. Size and age, water temperature, and maintenance requirements affect the protein requirements of fishes. Various investigators have observed improved growth and feed efficiency when experimental diets for salmonids were supplemented with indispensable amino acids to simulate levels found in isolated fish protein or the respective eggs and whole-body tissue of the species being studied. The indispensable amino acid requirements of certain fish have also been shown to correlate well with the indispensable amino acid pattern of the whole-body tissue of that fish.

Amino acids and proteins

Many feed ingredients in use in monogastric diets contain significant quantities of antinutritional factors (ANF) which limit both their feed value and their use. Almost all enzymes currently being used address such factors to varying degrees, allowing for more economic utilization of raw materials. However, animal response to xylanase, beta-glucanase and even phytase utilization reported in the literature tends to vary. Factors such as enzyme source, ingredient variety and environment under which the ingredient was grown, stored and processed into animal feed, age of animal, interaction with other dietary ingredients, and health status are shown to affect significantly the response obtained. As a result, the mode of action of xylanases and beta-glucanases is still debated due to too much emphasis being placed on interpretation of individual trial results without regard to the interactive factors or the literature dataset as a whole. Better understanding of such factors will improve data interpretation. While results with phytase are not subject to such extreme variation, they are nevertheless inconsistent in the degree to which inorganic phosphorus can be replaced by this enzyme. Greater understanding of the ANF and factors which interact to govern the response to added exogenous enzymes will undoubtedly improve the economic return and confidence in their use. Improved knowledge of ANF structure will result in development of enzymes directed towards far more specific targets, which enhances the likelihood of success and should reduce the overall enzyme usage.

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Exogenous enzymes for pigs and poultry

We studied the effects of increasing dietary concentrations of each of the following amino acids on growth, feed intake, feed conversion ratio and composition of gain in rainbow trout in six dose-response experiments: L-lysine, L-tryptophan, L-histidine, L-valine, L-leucine and L-isoleucine. Semipurified diets containing 20.1 MJ digestible energy/kg dry matter, with wheat gluten and crystalline amino acids as sole sources of amino acids, were fed to rainbow trout [initial mean body weight (BW) 40-51 g, depending on the amino acid studied]. In one series of 24 diets, lysine concentration ranged from 4.5 to 58.0 g/kg dry matter; in five further series of 12 diets each, concentrations ranged from (in g/kg dry matter): tryptophan, 1.3 to 5.6; histidine, 2.6 to 13.5; valine, 6.2 to 34.2; leucine, 10.0 to 42.0 and isoleucine, 5.0 to 15.3. Each diet was fed to a group of 20 fish for 53-64 d, depending on the amino acid studied. Dry matter intake, weight gain, feed conversion ratio, protein concentration of gain and total protein deposition followed exponential response functions. To achieve 95% of the maximum protein deposition, dietary concentrations of 27.7 g lysine, 2.0 g tryptophan, 5.8 g histidine, 15.7 g valine, 13.6 g leucine and 13.7 g isoleucine/kg dry matter were required. Maintenance requirements, estimated from exponential functions for protein deposition, were [in mg/(100 g BW.d)]: lysine, 1.93; tryptophan, 1.05; histidine, 1.07; valine, 2.92; leucine, 8.26 and isoleucine, 0.91. This corresponds to 4% of the requirement for protein deposition for lysine and isoleucine but 32% for leucine, with the other amino acids being intermediate. Therefore, different dietary amino acid requirement patterns were derived from protein deposition data depending on the chosen level of performance.

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Response of Rainbow Trout (Oncorhynchus mykiss) to Supplements of Individual Essential Amino Acids in a Semipurified Diet, Including an Estimate of the Maintenance Requirement for Essential Amino Acids

Effects of supplemental microbial phytase on phosphorus digestibility and utilization in rainbow trout (oncorhynchus mykiss)

Empfehlungen zur Energie- und Nährstoffversorgung der Milchkühe und Aufzuchtrinder 2001

Effect of phosphorus intake on faecal and non-faecal phosphorus excretion in rainbow trout (Oncorhynchus mykiss) and the consequences for comparative phosphorus availability studies.

Ernst Pfeffer

Papers

Response of Rainbow Trout (Oncorhynchus mykiss) to Supplements of Individual Essential Amino Acids in a Semipurified Diet, Including an Estimate of the Maintenance Requirement for Essential Amino Acids

Effects of supplemental microbial phytase on phosphorus digestibility and utilization in rainbow trout (oncorhynchus mykiss)

Empfehlungen zur Energie- und Nährstoffversorgung der Milchkühe und Aufzuchtrinder 2001

Effect of phosphorus intake on faecal and non-faecal phosphorus excretion in rainbow trout (Oncorhynchus mykiss) and the consequences for comparative phosphorus availability studies.

Availability and utilisation of free lysine in rainbow trout (Oncorhynchus mykiss): 1. Effect of dietary crude protein level