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As a source of nutrients, fish contain protein, lipids, minerals, and vitamins. The proteins, as a whole, supply the essential amino acids in proportions to give a high biological value to the protein and to enable fish protein to be used as a supplement to protein sources of lower biological value. Discovery of the toxicity and carcinogenicity of N-nitrosodimethylamine caused concern regarding the possibility that nitrates and nitrites, used in curing salt, could react with amines present to form nitroso compounds. In one investigation 18 samples of smoked and five of canned fish were analyzed after cooking with and without sodium nitrite. Frozen storage of fishery products prevents microbial spoilage and retards most chemical changes, although some reactions may be accelerated. Denaturation of proteins, oxidation and hydrolysis of lipids, protein-lipid interactions, and protein-carbohydrate interactions can all take place during frozen storage.

Pigmentation development was studied in rainbow trout Oncorhynchus mykiss, chinook salmon O. tshawvytscha, and Atlantic salmon Salmo salar fed similar practical diets supplemented with 40, 70, or 100 mg astaxanthin/kg of diet. The initial mean body weights of the respective species were 158, 198, and 191 g. The rainbow trout were reared in freshwater at 6.0–11.3°C, the chinook salmon in seawater at 8.8–14.4°C, and the Atlantic salmon in seawater at 7.1–12.7°C. The response of flesh pigmentation to dietary pigment was most rapid in rainbow trout and slowest in Atlantic salmon. Chinook salmon showed the greatest variation in response to the different dietary concentrations of astaxanthin, followed by rainbow trout and Atlantic salmon. In both rainbow trout and Atlantic salmon, pigmentation was most intense in the distal section and decreased anteriorly. In chinook salmon, pigmentation was most intense in the midsection, followed by the anterior section and then the distal section. Postprandial plas...

Several artificial diets were tested for their ability to promote growth of gonads in the green sea urchin, Strongylocentrotus droebachiensis, over a 9-month period. Survival and test growth were also monitored, as were gonad lipid levels and water content (at the middle and end of the reproductive cycle only). The artificial diets differed in amount of protein and in the presence of various additives such as mannitol, algin, cholesterol, and β-carotene; a diet of air-dried kelp (Nereocystis luetkeana) was included for comparison. Survival was > 95% for all diets save a low-protein one (82% survival). Test diameters showed no significant change over time or among dietary treatments. All high-protein formulations produced significantly higher gonad indices than low-protein ones. Addition of β-carotene to the high-protein formulation significantly increased gonad growth relative to all other diets; this was especially noticeable in December, at the time of best market quality for the roe. Lipid levels were not significantly different among dietary treatments in either November or March, but did show a slight statistically significant rise between these months (21.4–22.7% dry mass). Water content also showed no significant difference among treatments, but was significantly higher in March (82% live weight), just prior to spawning, than in November (70%). Gonad indices for all artificial-diet formulations were higher than any previously recorded for S. droebachiensis.

It is proposed that the traditional interdisciplinary nature of the agricultural sciences be extended and integrated with management sciences pertaining to other renewable natural resources. Current conflicts between agriculturalists and environmentalists demonstrate the need for professionals whose educational background gives them an understanding of the issues involved. Policy decisions regarding the activities of renewable resource industries, compatible with sustainable development and the maintenance of environmental quality, demand that those making the decisions be knowledgeable about the industries involved, as well as understand environmental impacts. Similarly, those whose principal concerns are for wilderness and interface areas should be better informed for the optimum management of those areas with an understanding of underlying agricultural principles of animal and plant production. It is for these reasons that there should be a consolidation of faculties of agriculture, forestry, and fisheries, together with the units that have developed on most campuses to address such areas as environmental studies, water conservation, wildlife management, waste management, land use planning, landscape architecture, and bioresource engineering. Department of Animal Science, Univ. of British Columbia, Ste. 208, 2357 Main Mall, Vancouver, BC V6T 1Z4 Canada. Received 26 Aug. 1993. *Corresponding author. Published in J. Nat. Resour. Life Sci. Educ. 23:136-140 (1994). A INTERDISCIPLINARY APPROACH has always been understood by faculties and colleges of agricultural sciences to be logical in the study of plants and animals and the related aspects of the environment. The interdisciplinary approach has been recognized as the hallmark of university programs in agricultural sciences and has been an important factor in research resulting in advances in production agriculture. Increases in production and efficiency of production should no longer be viewed as the only criteria for judging the worth of agricultural endeavors. The added dimensions of sustainability of productivity and maintenance of environmental quality are .ittaining prominence for consideration. In accord with '.hese new perceptions of what should be considered as pirt of the responsibility of agriculturalists, the place of agricultural science and agricultural research within universities must be redefined. The knowledge and power of practices that have dealt so successfully with agricultural production in the past can be extended to areas generally designated as environment and natural resource management. The converse application of ways of thinking about the environment and of managing natural resources likewise has a role in production agriculture. Unless there is coordination of effort and objectives among specialists from a variety of disciplines, it is likely that whole sections of agriculturally based or directed research will be pulled away from 736 • J. Nat. Resour. Life Sci. Educ., Vol. 23, no. 2, 1994 faculties of agriculture. The sections most likely to separate themselves are those that can be set up to bear titles that include currently fashionable words such as biotechnology, land-use planning, sustainable, management, environmental, and conservation. These areas are derived, in many cases, from the classical disciplines in agriculture and their separation from the agricultural sciences will result in mutual loss. Their removal from under the agriculture umbrella takes away many of the more contemporary areas for research and teaching, areas that are most attractive to students and faculty. What remains in association with agriculture may not be sufficiently comprehensive to warrant constitution as a faculty or college. In recent years a great deal of thought has been given to ways of facilitating information transfer along the continuum from basic science through developmental technology to industrial application. The present trend of stripping away from faculties of agriculture (and from government departments of agriculture) everything that is not directly concerned with traditional production agriculture will, if continued, operate to the detriment of information transfer among areas that should be closely associated with the agricultural sciences. The increases in efficiency and productivity of agriculture have been such that only 2 to 3 °70 of the population in Canada and the USA is now engaged in on-the-farm agriculture. (Many more people are employed today in other agricultural industries and para-agricultural industries than in actual farming.) As a result, only a small proportion of the population has any knowledge, or even an awareness, of agricultural practices and the scientific basis for those practices, despite the fact that the activities associated with high technology agriculture are interwoven with all aspects of life on earth. It is regrettable that government policy decisions that affect production agriculture are being made today by thoroughly urbanized people who lack understanding of the techniques and requirements of food production and handling. A recent paper by Brown and Coffey (1992) describes an attempt to address this problem by a course at Western Kentucky University entitled The Science of Agriculture. This course is offered as part of a general education in science requirement for nonagriculture majors. The course is intended to give a broad view of agriculture and the role of science in it. Gradually, during the past 50 yr, the image of agriculture for the increasing urban population has split so that, on the one side there is the nostalgic view of agriculture as an idyllic way of life, and on the other, of production systems dominated by chemicals, genetic engineering, factory farms, and enormous machines. Neither of these perceptions of agriculture is persuasive of bright, young people to educate themselves for careers in agriculture. Potential students have no way of knowing that agricultural sciences represent the integration of many disciplines including the basis sciences. They find it difficult to be excited about a discipline that appears to be directed only toward increased food production when they read about the problems of disposal of surplus products and payments to farmers for holding agricultural land out of production. They are not being informed about the exciting opportunities that exist for the management and integration of agriculture within the total ecological framework and the opportunities that exist for application of agricultural techniques to the management of the larger environment. James H. Meyer, chancellor emeritus of the University of California at Davis, recently (1992) observed that the land-grant colleges of agriculture in the USA are "baffled" to identify and address the challenges they confront. He suggests that the original land-grant college model be altered to meet today’s need for interdisciplinary, interdepartmental, and multidisciplinary research. Agriculturalists, having been so successful in achieving productive systems for food and fiber, should now be applying their knowledge and techniques to assure sustainability of agricultural production. Not only that, but knowledge gained regarding management of agricultural systems needs to be further developed and applied to the management of the larger ecosystems constituting the entire environment. Instead of assuming a leading and expanding role for the disciplines of agriculture in research, teaching, and management of natural resources, agriculturists have been slow to respond to these new opportunities. In fact, there seems to have been a notable lack of enthusiasm and imagination. As a result of the failure of agriculturalists in academia and in government agencies to expand their mandates, the scope of professional agriculturalists has been narrowing. Reflecting this phenomenon is a warning from Rep. Pat Roberts (1993) from Kansas and a member of the House Agriculture Committee. Roberts states that there is a danger that other agencies and departments will peel off functions now vested in the USDA for their own jurisdictions and that USDA may be restructured out of existence. (The following discusses background considerations for a consolidation of academic disciplines dealing with the understanding and management of global and local ecosystems to achieve the sustainability of productivity and environmental quality.)

This paper emphasizes those aspects of fatty acid research in fish that have relevance to the investigation of the functions of essential fatty acids in other species. Lipid requirements of fish came under investigation only in the 1960s. The most significant finding has been the requirement for n − 3 fatty acids. The dietary ratio of (n − 3):(n − 6) is critical if the essential requirement is met by C18 fatty acids because of competition between fatty acids for the enzymes involved in elongation and desaturation to produce the physiologically essential long-chain fatty acids. The fatty acid composition of fish lipids varies according to the fatty acid profile of the dietary lipid. The fatty acid composition of fish also responds to temperature changes in an adaptive mechanism for maintenance of membrane homeoviscosity and physiological function over a range of temperatures. The dietary intake of essential fatty acids by brood stock must be adequate for ova formation and for embryonic development, with the latter requirement being more critical for reproductive success. Absolute requirements of fish for essential fatty acids are difficult to define and may vary depending upon the dietary ratio of (n − 3) to (n − 6) fatty acids.Key words: essential fatty acids, nutritive requirements, fish.

The fatty acid profiles of lipids extracted from eggs and alevins of cultured chinook salmon (Oncorhynchus tshawytscha) were significantly different than those from eggs and alevins of wild fish of the same stock. The mean total concentrations of n3 fatty acids in the total lipid of eggs from wild and cultured broodstock were 40.2 and 29.4% and in the polar lipid 45.5 and 38.7% respectively. The mean concentrations of n3 fatty acids in the total lipid of alevins from wild and cultured broodstock were 35.4% and 23.2% and in the polar lipid 43.0 and 38.2%, respectively. The ratios of n3:n6 fatty acids were lower in both the neutral and polar lipids of eggs and of alevins from the cultured fish than in those of wild fish. The higher n3:n6 fatty acid ratios in the eggs and progeny of wild fish reflected the higher ratios in lipids of components of the natural marine food chain.

Canola meals (two commercial meals and one low-heat meal) were processed to reduce fiber content, then washed with selected solvents to reduce the content of antinutritional substances and further concentrate protein. The meals, fiber-reduced meals, and washed meals were used to provide 40% of total protein (26–38% of feed) in the diets of 6-g rainbow trout for 3 weeks or 25% of total protein (21–31% of feed) in the diets of 23-g chinook salmon for 11 weeks. Air-desolventized (low-heat) canola meal, as compared to commercial meal, provided no protein quality advantage in trout feeds. Fiber reduction processing of commercial meal increased meal protein content by 11–16% and reduced crude fiber by 23–50%, but did not have any effect on the quality of protein for trout or salmon. Solvent-washing of fiber-reduced meal improved fish response to canola meal, probably due to reduced glucosinolate content, but possibly also due to reduced sinapine content and alterations in protein availability. Protein concentration was increased by 25–40% by washing, and glucosinolate concentration was reduced by 40–90%.

Experiments were conducted to determine whether poor intestinal absorption of astaxanthin or some other metabolic factor is primarily responsible for pigmentation failure in white chinook salmon and small juvenile fish of other salmonid species. None of the fish studied failed to absorb astaxanthin from a single oral dose of the pigment. Intensity of flesh pigmentation in coho ranging in weight from 30–400 g, and fed a diet supplemented with astaxanthin, was significantly correlated with body weight. There was no correlation, however, between flesh colour and plasma astaxanthin concentration or between body weight and plasma astaxanthin concentration. Dietary triiodothyronine reduced both flesh pigmentation and plasma astaxanthin. It is concluded that poor flesh pigmentation results from rapid metabolism of absorbed pigment to colourless derivatives rather than from failure of the fish to absorb pigment.

Diets supplemented with 5% of tallow or safflower oil were fed to White Leghorn pullets during the initial 14 wk of production. The diets contained .6% and 4.3% of linoleic acid, respectively. Egg weight was consistently greater with the diet high in linoleic acid. Yolk weights relative to egg weights were similar in each sample, as were the yolk concentrations of total, neutral, and polar lipids. The fatty-acid profiles for both the neutral and the polar fractions were also similar for the large and small eggs within treatment, but there were differences between treatments. The lipid concentrations in the liver at the conclusion of the experiment were greater in the birds fed the diet low in linoleic acid as a result of increases in the neutral lipids. As with the yolk fatty acids, the substitution of safflower oil for tallow in the diet decreased the concentrations of oleic acid and increased the concentrations of linoleic acid in both lipid fractions. The constancy of the proportions of protein, neutral lipid, and polar lipid in the yolk, despite the effect of dietary linoleic-acid concentration on yolk size, supports the hypothesis that linoleic acid, or longer-chain fatty acids of the linoleic-acid family, is required for the synthesis of the lipoproteins that can be transported to the ovary for uptake by the developing ova. Egg size cannot be maximized if the amount of linoleic acid available is not adequate to support the maximum rate of synthesis by the lipoproteins.

Plasma amino acid profiles in the systemic circulation of rainbow trout acclimated to diets containing different protein sources, with and without supplementation with free amino acids, were monitored for up to 120 hours after consumption of the diets. Plasma concentrations of lysine, methionine, and isoleucine increased more rapidly after feeding a diet supplemented with these amino acids in free form and, depending upon the increase in plasma concentration, remained at concentrations above those in fish fed the basal diet for at least 24h after feeding. Dietary supplementation with isoleucine increased plasma concentrations of leucine and valine as well as of isoleucine. Maximum plasma concentrations for most amino acids were attained between 12 and 24h postprandial. Dietary inclusion of gelatin caused more rapid elevations in plasma glycine and serine than did free glycine. Feeding at three hour intervals resulted in stable plasma concentrations of individual amino acids in contrast to the fluctuations occurring when fish were fed once daily. Frequent feeding favoured a higher proportion of protein to lipid in body composition.

Growth rate and efficiency of feed conversion were reduced by inclusion of oxidized herring oil in the diet, presumably as a result of reduced digestibility of the oxidized oil and suboptimal dietary concentrations of ω3 fatty acids. There was no evidence of any toxic factors in the oxidized oil. There was no significant difference in growth rate or the efficiency of feed conversion between juvenile coho fed diets supplemented with 30 and 1030 IU vitamin E/kg. Dietary treatment did not affect haematocrit values. Immunocompetence, judged by antibody titres in response to vibrio vaccination, was similar for all treatments. Disease resistance, assessed by the rate of mortality induced by exposure of nonvaccinated fish to challenge with Vibrio anguillarum or V. ordali, was likewise unaffected by the dietary treatments.

The effects of dietary excess of vitamin A on one-stage prothrombin time and on one-stage euglobulin-lysis time were studied in Single Comb White Leghorn, New Hampshire, and Black Australorp chicks. Prothrombin time was increased by the feeding of 100 000 and 200 000 I.U. of vitamin A per kilogram of diet to the Black Australorp chicks but it was not increased when these amounts of vitamin A were fed to either the White Leghorn or the New Hampshire chicks. The prolongation of prothrombin time was reversed within 16 h by injection of menadione. Vitamin A at 100 000 and 200 000 I.U./kg of diet decreased euglobulin-lysis times in chicks of all three breeds but increased the concentration of fibrinogen in the plasma. The effect of excess vitamin A on euglobulin-lysis time was not associated with induced vitamin K deficiency. The decreased euglobulin-lysis time resulting from intake of excess vitamin A persisted for 6 weeks subsequent to the feeding of moderate amounts of vitamin A.

Hens were given supplementary calcium in the form of 5.7% dietary limestone or oyster shell ad libitum separately from the diet. The two calcium sources were given as supplements to four different diets; wheat-based diets containing soybean meal (SBM) or rapeseed meal (RSM) as the source of supplementary protein and either tallow or corn oil as a fat supplement. Over the 20 weeks of the experiment there were no differences in the rates of production of the birds among the eight experimental treatments. Yolk weight was reduced when the hens fed the diets with tallow as the supplementary fat received their supplementary calcium as oyster shell. When the 5.7% of supplementary limestone was exluded from the weight of feed consumed by the hens given all their calcium mixed into the diet, there was no difference in the amount of feed consumed by the birds on the two systems of calcium feeding. The efficiency of feed conversion to egg meat production was likewise similar for both systems of calcium feeding under the different dietary treatments imposed. Regardless of the composition of the diet, shell weight per unit surface area was greater for the eggs laid by the birds fed oyster shell.

White Leghorn pullets of two strains were fed soybean or rapeseed meal during either or both the growing period and laying period in two separate experiments. Rapeseed meal may be fed to growing pullets at levels up to 17% of the diet without adversely affecting the subsequent rate of egg production or egg size. Birds fed laying diets containing 19% of rapeseed meal produced a greater egg mass per hen-day and gained more weight during the laying period when the growing diet contained rapeseed meal instead of soybean meal. Birds shifted at sexual maturity from soybean to rapeseed meal as dietary protein supplement undergo metabolic adjustment which retards the attainment of maximum rate of production and induces cannibalism. Both rate of production and egg size were lower when rapeseed meal constituted 19% of the laying diet in replacement of soybean meal as protein supplement. Mortality, exclusive of that resulting from cannibalism, was 4.1% and 4.6% respectively in the two experiments. Death from liver haemorrhage occurred only in birds of one strain which were fed rapeseed meal during the laying period and principally in birds which had been fed rapeseed meal during the growing period as well.

A control fish meal and an overheated fish meal were compared by in vitro digestion with pepsin at concentrations of 10−5 to 10−1 and at temperatures from 10 to 40 °C. The reduction in protein solubilization caused by over-heating was most evident with pepsin digestion at 10 and 20 °C and suggests modification of the standard method when evaluating fish meals to be fed to cold-water fish. Key words: Protein digestibility, pepsin digestibility, fish meal, cold-water fish

Herring meals prepared with and without the addition of 0.025% of 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline (EQ) were stored for ten months at -20 oC and 21 oC. Storage changes in the biologically determined energy and protein values of the meals were monitored and related to changes in the chemical characteristics of the meal. Antioxidant treatment stabilised the meal lipid against oxidative changes resulting in loss of solubility, decline in iodine value and formation of peroxides and malonaldehyde. The effect of storage temperature on the course of oxidation depended upon whether the meal was treated with EQ. Lipid in meals without EQ tended to show greater change early in the storage period at -20 oC. Antioxidant-treated meals showed protection of the protein against changes leading to reduced digestibility and lysine availability. Either antioxidant treatment or storage at -20 oC protected the biological availability of the energy-supplying nutrients present in the meal.

Philosophers, scientists, vegetarians, livestock producers, sealers, and film stars are debating the morality of human use of animals for food and clothing, for sport, as companions, and as experimental subjects in research. They are debating the entitlement of animals to rights and human responsibility to assure those rights. These are not new philosophical problems. The present surge of concern for animals by people belonging to a largely urban society who have had little association with animals is, however, a curious phenomenon with diverse origins (see also Ritvo 1984, p. 626 this issue). A number of events in recent years point to increasing human awareness of our relationship to the other animals with which we share the earth. Organizations have formed with the objective of protecting endangered species. Trapping wild animals and slaughtering seals for their pelts have been much publicized. Studies have been done of the conditions under which domestic animals are reared for food. Some countries have enacted

Three composite samples of whitefish meals, each representing samples over 4 mo from plants in eastern Canada were analyzed for proximate composition, minerals, vitamins, amino acids, available lysine, and pepsin digestibility. Protein quality was evaluated biologically in feeding trials with chicks. The composite samples were similar in chemical composition with respect to both macro- and micronutrients. In vitro pepsin digestibility was 95–96% and chemically estimated available lysine 6.5–6.9 g/16 g N, or 87–96% of the total lysine present. The growth response to the meals, when they were fed to supply either 4 or 8% of supplementary protein in diets containing a total of 14.5 or 18.5% of protein, respectively, indicated that the supplementary protein value was high.

Broiler-type chickens were subjected to dietary restriction for up to 14 weeks. Body weights and composition were measured in the birds at 42 weeks of age. The body weights of birds subjected to feed restriction from day-old to 12 and 14 weeks of age remained significantly lower than those of the control birds. The lighter weights appeared to be due to a reduction in the growth of all tissues, since the proportional weights of the M. pectoralis major, liver, reproductive tract, tibiotarsus, and adipose depots were similar in the restricted and the control birds. Adipocyte size in the retroperitoneal depot increased in the birds on all treatments between 18 and 42 weeks of age. Dietary restriction for 12 and 14 weeks suppressed adipocyte growth and the effect on cell size was still apparent in the retroperitoneal and the M. sartorius adipose depots when the birds were 42 weeks old. Adipocyte numbers in the retroperitoneal depot were significantly greater in the birds subjected to feed restriction for 12 and 14 weeks. The increase in retroperitoneal adipocytes in these birds was caused by an increase in the number of small cells. The number of large retroperitoneal adipocytes in the birds on restricted feed intake for 14 weeks was greatly reduced. Adipocyte numbers in the M. sartorius depot were not affected by feed restriction for up to 14 weeks.

The growth rate and survival of the Capilano (hatchery) and Harrison (wild) strains of chinook salmon ( O. tshawytscha ) of British Columbia and their hybrids reared in confinement were compared both during the fresh-water phase and the sea-water phase. Eggs stripped from the Capilano females had better fertility, fingerlings of the Capilano strain were heavier at 25 weeks of age and had a higher average specific growth rate. The Capilano fish were also heavier both in live weight and gutted weight after 1.5 years in sea-pens. No heterosis was detected for any of the traits measured. Cross-means for body weight and specific growth rate tended to be similar to the strain-of-sire mean.

The caeca and small intestine of chickens consistently contain trimethylamine (TMA). The caecal contents in the birds studied ranged from 4 to 55 μg TMA/g and contained the higher concentrations when the diet contained rapeseed meal or supplementary choline. The amounts of TMA in the small intestine were lower (1 to 21 μg/g) and were less influenced by dietary composition. Supplementary choline in the diet of laying birds induced the production of tainted eggs by some birds. The yolks of tainted eggs contained concentrations of TMA which were consistent for each bird. TMA was also present in the follicular yolks of all sizes in the ovaries of birds which laid tainted eggs. It is postulated that, in birds laying tainted eggs, failure of the liver to oxidize TMA is responsible for deposition of TMA in egg yolk.

New Hampshire chicks utilized dietary fat more efficiently than did broiler-type or White Leghorn chicks. The difference was more pronounced with tallow than with corn oil. Utilization of fat by all three types of chicks increased until the chicks were about six weeks old. At hatching, the concentration of fatty acid binding protein (FABP) in the intestine of the broiler-type chicks was significantly less than in the New Hampshire and White Leghorn chicks. Concentration of FABP declined during the first 1 to 2 weeks of life and then increased. By four weeks of age the breed differences in concentration of FABP in the intestine were no longer apparent. At some time after four weeks of age, FABP reached maximum concentrations in the intestinal tissue of the chicks of different breeds and thereafter declined as a proportion of the total intestinal tissue. Broiler-type chicks, which did not utilize fat as efficiently as did New Hampshire chicks in the first weeks of life, displayed lower concentrations in the proximal third of the intestine and higher concentrations in the remainder of the intestine than was the case with the New Hampshire chicks. A high level of dietary fat or dietary supplementation with sodium taurocholate increased the concentration of FABP in the intestine.

Female broiler-type chickens were fed diets containing different concentrations of protein and fat in two experiments. The first experiment was for 4 weeks. The mean weights of the abdominal fat pads were inversely related to dietary concentrations of protein between 20 and 35%. Adipocyte size and cellularity of the fat pads were lower with 30 than 20% protein. Fat deposition in the abdominal pad was increased in 3-week-old chicks by isocaloric substitution of oil for starch in the diets. At 4 weeks of age the effect of oil was not significant with 30 or 20% dietary protein (no measurements were made in chicks fed 35 or 25% protein). In Experiment 2, the development of the abdominal fat pad in birds fed 18 to 33% protein was monitored for 22 weeks. By 7 weeks the distribution of adipocyte size was bimodal. The initial adipocyte population showed comparatively little increase in numbers after 12 weeks, but cell size continued to increase. The numbers of adippcytes in the second population of adipocytes was still increasing rapidly at 22 weeks, although the size of the cells in this population remained small. At 22 weeks the small cells constituted 62% of the total adipocyte population but contained only 2.4% of the lipid in the fat pad. Adipocyte cell size was significantly affected by dietary protein and energy until 9 weeks of age, but the effects subsequently declined.

Nutrient composition studies have been carried out on single samples of meals produced from whole Atlantic argentines (Argentina silus), capelin (Mallotus villosus), American sand lance (Ammodytes americanus) and from filleting scrap from flounders (Pleuronectidae sp.) and redfish (Sebastes marinus).Analyses included protein, fat, ash, moisture, minerals, vitamins, available lysine, amino acids, and protein digestibility. The whole fish meals appeared nutritionally equal to good herring meal. The filleting scrap meals were lower in protein content but the nutritional values of the proteins were equivalent to that of herring.

One thousand broiler-type pullets were reared with feed restriction from 5 weeks of age to attain a target average body weight of 1.64 kg at 18 weeks of age. Thereafter feed was supplied at the rate of 130 g per bird per day until 47 weeks at which time half the population was fed ad libitum. An additional treatment was imposed at 86 weeks when 12 birds were gradually but severely restricted in feed intake until, by 97 weeks, they were receiving only 40 g feed per day. Birds restricted in feed intake until 47 weeks and then fed ad libitum increased consumption sharply and in proportion to body weight for approximately 2 weeks. Thereafter, intake declined to about 20% in excess of the restricted level for the next 16 weeks. Body weight increased with the increased feed intake. Average adipocyte diameter increased with the age of the birds even when feed was restricted. There was no increase in the number of adipocytes present in the retroperitoneal fat pad after 27 weeks of age. The size distribution of adipocytes was consistently bimodal except following severe feed restriction when the weight of the fat pad regressed and the secondary peak of small adipocytes disappeared.

Virginiamycin at a dietary concentration of 22 ppm stimulated growth rate and improved efficiency of feed conversion in broilers fed different diets. The dietary variations were practical ones which would alter the milieu of the intestinal bacteria. They involved the use of wheat vs. corn as principal dietary cereal, different levels of fat, and different levels of protein. All the diets supported similar performance and there were no significant interactions in response between diet and antibiotic. Body weights at 53 days of age averaged 5% heavier in the virginiamycin-fed birds and the average rate of improvement in feed conversion efficiency was 5.4%. At 26 days respective values for the above were 10.3% and 9.5%. The energy metabolized from the diets was increased by 7.2% when the diets contained virginiamycin.

White Leghorn chicks were fed diets containing either soybean meal or rapeseed meal as the source of supplementary protein. The diets were modified by the addition of corn oil, corn oil plus erucic acid, cornstarch, or herring meal. Excreta from the chicks were analyzed for ether-soluble lipid and for the amounts of fatty acids present in soaps. The birds fed the different soybean meal-containing diets in three experiments excreted, on the average, 30.2% of lipid in the form of soap fatty acid. Those fed the equivalent diets containing rapeseed meal excreted 16.6% of lipid in the form of soap fatty acid. Differences in the proportions of fatty acids excreted as soaps are attributed primarily to differences in concentration of ionic calcium in the intestinal lumen.

White Leghorn pullets of two strains were fed 20% of Tower rapeseed meal in the laying diet for one year. The rapeseed meal was manufactured with and without addition of 2% of either Tower or Midas gums. Control birds were fed a soybean meal diet. Each diet was fed to 1018 birds of two commercial lines. Rate of production during a one-year period was similar on all diets. Gums were without effect on any aspect of production. Overall mortality in the experiment was 11.7%, or 6.5% when neoplasms were excluded. There was a strain difference in the rate of mortality which was not due to any single cause. The birds fed the rapeseed meal with Midas gums had the highest mortality. The incidence of haemorrhagic lesions in various tissues was significantly affected by diet, being lowest in the birds fed the soybean meal diet and highest in the birds fed the rapeseed meal with added Midas gums.

In order to study the inheritance of flesh pigmentation in chinook salmon, a 6×6 factorial cross was set up by fertilizing eggs from three white (W)- and three red (R)-fleshed chinook salmon with milt from three W- and three R-fleshed salmon to give 36 full-sib families. During the last 7 months before colour-scoring all fish were fed a diet supplemented with astaxanthin added in an oil carrier. Flesh pigmentation was measured against a colour fan at approximately 120 weeks of age and scored on a scale of 1–8. Progeny from RR matings were more pigmented than progeny from WW matings and the pigmentation in the progeny from the crosses was more dependent on the pigmentation of the dam than the sire. There was no significant correlation between the degree of pigmentation and the lipid concentration of the flesh. The results demonstrated that chinook salmon, fed the same diet containing astaxanthin, may show wide variation between strains as well as among families within strains in ability to utilize the dietary pigment. Such heterogeneity among parents within strains suggests that the expression of pigmentation is controlled by a small number of genes with large non-additive effects.

Two herring meals containing 0.17 and 0.22 p.p.m. of mercury respectively were fed to broilers at dietary levels of 5, 10 and 17.1%. The amounts of mercury present in the diet from this source thus varied from 0.0085 to 0.0376 p.p.m. Growth rate and mortality to eight weeks of age were unaffected by the level or source of herring meal in the diet. The amount of mercury ingested by the birds fed any of the diets resulted in negligible effects on the concentration of mercury present in breast or leg muscle. There was, however, significant accumulation of mercury in liver, kidney, claw and feather tissue, which reflected the dietary concentration of mercury. The amount present in the feathers was high as 0.845 p.p.m. This amount may be sufficiently high to warrant concern when feathers are processed into meal.

No significant differences in plasma corticosterone concentrations were noted among chicks fed diets containing 16 to 25% protein or diets containing 2,800, 3,200, or 3,600 kcal metabolizable energy per kg to 6 wk of age. The ingredients used in diet formulation did, however, affect plasma corticosterone. Higher plasma corticosterone was associated with 2,800-kcal diets containing high concentrations of cornstarch and no cereal grains compared with 2,800-kcal diets containing low concentrations of cornstarch and cereal grains. In a second experiment, chicks were fed diets containing different concentrations of lysine and methionine from hatching to 4 wk of age. Half the chicks on each dietary treatment were conditioned to handling by daily gentling. Plasma corticosterone concentrations were reduced in the conditioned chicks. Plasma corticosterone increased during a period of up to 15 min after catching when the chicks were kept in a box prior to drawing blood samples. Excess dietary lysine significantly reduced plasma corticosterone in the gentled chicks but not in the control chicks.

1. Single Comb White Leghorn hens of 2 ages (44 and 80 weeks) were fed diets of different energy (10.88, 12.13 or 13.39 MJ ME and 140 g protein/kg) or protein (120, 140, 160 or 180 g and 12.13 MJ ME/kg) concentration over an 8-week period. 2. Food intake did not change with increasing concentrations of dietary protein. Protein intake was directly correlated with dietary protein concentration. 3. Energy intake increased with dietary energy concentration but, generally, failed to match the increases in dietary energy concentration. Energy, rather than protein, concentration was the major determinant of food intake. 4. Efficiency of energy utilisation decreased and mean adipocyte size increased with higher energy intake. 5. A bimodal adipocyte size distribution, consisting of a primary large size and a secondary small size population, was present in the abdominal fat pad of birds of both ages. There was no significant difference in the numbers of large adipocytes between the hens of the two ages. 6. The greater mean fat pad weight in the older hens was associated with increased mean cell volume in the population of large adipocytes.

Broiler-type and White Leghorn chicks were given diets containing 30.5, 26.2, or 22.3% protein with and without addition of 5% corn oil during an 8- to 9-week conditioning period. The absolute weight of the abdominal fat pad was greater in the broiler-type birds on all dietary treatments. As a percentage of body weight the abdominal fat pads were similar in broiler-type and White Leghorn birds only when the diet contained 30.5% of protein without added oil. Following a 16-hr fast, plasma glucose was higher in the broiler-type than in the White Leghorn birds, whereas plasma triglyceride concentrations were higher in White Leghorns. In birds refed a high-fat meal, plasma glucose showed little change except in the broiler chickens previously fed the 30.5% protein diet without added oil. In these birds plasma glucose declined over a 5-hr period to reach a mean value of 130 mg/100 ml. Plasma triglyceride concentrations in both breeds were markedly elevated within 45 min of refeeding with a high-fat meal, but the peak concentrations were higher in the White Leghorns than in the broiler-type birds. Previous consumption of the high-oil diet increased postprandial triglyceride concentration in the plasma of the broiler-type but reduced it in the White Leghorn chickens. The difference in response of the chickens of the different genetic stocks is attributed to differences in the development of the activities of the systems associated with 1) fatty acid absorption and movement of triglycerides from the intestinal mucosa to the circulation and 2) clearance of plasma triglycerides to the adipocytes as a result of lipoprotein lipase activity.

Selection of the test fish for uniformity of body weight allowed bioassays for protein quality to be conducted within a 3-week period with small numbers of fish. Slope-ratios from the linear responses of body weight gain to graded levels of protein intake gave practical comparisons of the quality of protein sources. The use of different dietary concentrations of protein sources under test may indicate responses to factors other than those associated with protein per se. The slope-ratio technique lends itself to simultaneous estimations of the relative efficiency of protein energy utilization, which are important in evaluation of plant protein concentrates.

The effects of overstimulation of the thyroid gland induced by the feeding of rapeseed meal or thiouracil during the growing period persisted for as long as 75 weeks after withdrawal of the source of goitrogen from the diet. Thyroid weight, thyroid iodine content and radioiodine uptake were all increased in birds which had received goitrogen during the growing period. Follicle diameter was greater and the height of epithelial cells was lower than in control birds. The thyroid changes in these birds were deduced to be compensatory because production characteristics were normal and distribution of a dose of radioiodine into thyronines (T3 + T4) was similar in the birds which had received goitrogen during the growing period and in the control birds. Birds which were being fed rapeseed meal at the time the thyroid glands were examined showed effects which varied in magnitude according to the length of time over which rapeseed meal had been fed. Thyroid weight, follicle diameter, amount of epithelial tissue present and the total amount of iodine in the thyroid glands increased, whereas coupling efficiency (radioiodine-labelled T3 + T4)/(monoiodotyrosine/diiodotyrosine) declined with time.

White Leghorn pullets were fed laying diets containing soybean meal or rapeseed meal as the source of supplementary protein and with or without 1,000 mg/kg of supplementary choline. Egg production was higher with soybean meal than with rapeseed meal but was unaffected by choline supplementation of the diets. Average egg weights were similar under all treatments. The yolk represented a larger proportion of the egg meat when soybean was the protein supplement. The addition of choline did not affect the relative weights of yolk and albumen with either the soybean or the rapeseed meal diet. The livers of the birds fed soybean meal contained a higher percentage of fat than did the livers of birds fed rapeseed meal. When choline was added to the diets the concentrations of fat in the liver were reduced by 23.5 and 28.2% in the birds fed the soybean meal and rapeseed meal, respectively. Incidence and causes of mortality were unaffected by the dietary treatments imposed.

Estimates of the metabolizable energy values of rapeseed meal are more variable than of other feedstuffs. Supplementation of diets containing rapeseed meal with the antibiotics oleandomycin and bacitracin sometimes increased, and sometimes decreased, the estimates of metabolizable energy. The feeding of rapeseed meal resulted in increased intestinal weights except when the diet was supplemented with antibiotic. It was concluded that the effect of rapeseed meal in limiting utilization of dietary nutrients is mediated through modification of the intestinal microflora. Variations in response to rapeseed meal may accordingly be due to differences in the dominant microflora present in the digestive tract of the birds.

Three rapeseed meals were analyzed and found to contain 4650, 5060, and 5720 mg choline per kilogram, respectively. Three broiler diets formulated with 20% of the respective rapeseed meals, and each containing in excess of 1500 mg choline per kilogram, did not promote as rapid growth as did a control soybean meal diet containing 1000 mg choline per kilogram. Incidence of perosis was higher with the rapeseed meal diets than with the soybean meal diets. Addition of choline to the soybean meal diet affected neither growth nor incidence of perosis in the birds fed this diet. Supplementary choline increased growth and decreased incidence of perosis in the birds fed the rapeseed meal diets. In a second experiment to study availability of choline from rapeseed meal, chicks were fed a diet containing 28% rapeseed meal and 2310 mg choline per kilogram or a soybean meal diet supplemented with choline to provide a total of 2110 mg choline per kilogram. The freeze-dried contents of the lower intestine contained 4.92 mg choline per gram from the rapeseed meal-fed chicks and 2.45 mg/g from the soybean meal-fed chicks. The results of the third experiment showed that unabsorbed choline in the intestine was associated with an increase in bacterial production of trimethylamine. The caecal contents of chicks fed 28% of dietary rapeseed meal contained significantly more trimethylamine than those of chicks fed a control soybean meal diet although both diets contained 2310 mg choline per kilogram.

A model system of egg albumin and herring oil was studied during storage at 21 oC and -20 oC. Chemical changes in the oil and protein were monitored by determinations of ether-extractable lipid, iodine value, peroxide value, thio-barbituric acid value, ultraviolet absorption of the oil, in vitro digestibility and available lysine. The model system showed greater changes during storage with respect to both protein and oil than did either the albumin or the oil stored separately. Similar determinations were made on a freeze-dried herring meal stored at 21 oC in nitrogen and on a sample of the presscake (from which the meal was made) stored at -20 oC. Available lysine level was a more sensitive criterion of protein alteration during storage than was pepsin-digestibility. The absorption at 233 nm of extractable lipid from both the model and the natural systems was associated with the loss in lysine availability during the storage period. Ultraviolet absorbance of the lipid more closely reflected the rate at which lysine availability declined than did TBA or peroxide values.

The variable effect of excessive vitamin A intake on alimentary cholesterolemia was investigated in cockerels of strains of White Leghorns and New Hampshires. With the New Hampshire cockerels, the feeding of 0.5% of dietary cholesterol resulted in greater cholesterolemia when the diet contained 1 700 I.U. of vitamin A per kilogram than when it contained 22 000 I.U. of vitamin A per kilogram. With the White Leghorn cockerels, on the other hand, cholesterolemia was enhanced with the higher level of dietary vitamin A. Absorption of a single oral dose of cholesterol was increased in birds of both breeds when vitamin A had been given previously by injection. In the White Leghorn cockerels the percentage of newly absorbed cholesterol in the hepatic pool was reduced by vitamin A administration, whereas in the New Hampshire cockerels the percentage was increased. It was concluded that excess vitamin A may have divergent effects on alimentary cholesterolemia in chickens of different genetic backgrounds as a result of opposite effects on the liver–blood ratio of a large load of cholesterol.

THE hatchability of turkey eggs, as a general rule, declines after the 9th to the 12th week of the breeding season (Dickens et al., 1941; Atkinson et al., 1955; Jensen et al., 1956). This is particularly true of the hatchability of eggs from broad-breasted stock, and it has been suggested that the hens may become depleted of some nutrient or nutrients. In recent years the importance of vitamin E, niacin, pantothenic acid and folacin has been established in the maintenance of hatchability (Jensen, 1953; Scott and Nelson, 1955; Atkinson et al., 1955; Kratzer et al., 1955, 1956; Ferguson et al., 1956). Declining hatchability of fertile eggs is usually accompanied by a decline in fertility. Atkinson et al. (1955) reported that supplementation of diets with dehydrated alfalfa meal and condensed fish solubles resulted in maintaining fertility at a high level throughout a 17-week breeding period. The object of the present experiment …

Breed and sex differences were observed in erythrocyte counts in the chicken. A difference in osmotic fragility of erythrocytes was found between chickens of the New Hampshire and White Leghorn breeds. Erythrocytes from mature males were more susceptible to osmotic hemolysis than were erythrocytes from mature females. Lipids extracted from ghosts of erythrocytes from mature females or from males treated with diethylstilbestrol contained a higher proportion of oleic to stearic acid than did those from male birds. Incubation of erythrocytes in plasma derived from birds of the opposite sex increased the osmotic stability of ceils from males and decreased the stability of cells from females in comparison with the stability of erythrocytes incubated in autologous plasma.

THE FOLLOWING experiment was conducted to study the effects of introducing fat into the ration of mature laying birds previously fed starting, growing and laying diets not supplemented with fat. Data on body weight, mortality, egg production rate, egg size, albumen quality, egg shell thickness and feed consumption are presented. EXPERIMENTAL The birds used were 300 White Leghorn pullets which were already in lay (11 months old) when they were fed the rations supplemented with different levels of fat. Five and 10 percent of tallow† were fed to the birds in the rations shown in Table 1. The control ration and rations 2 and 3 were formulated to supply 1270 Cal. metabolizable energy per lb. (based on average energy values given by Potter et al., 1961). Ration 4 contained 10 percent tallow, but no attempt was made to have the ration isocaloric with the other rations, and its calculated metabolizable …

THE generally recommended level of protein for laying rations is 15 percent. Reports continually appear, however, to indicate that higher levels of protein are of advantage, and, conversely, that satisfactory performance may be achieved with lower levels of protein. The variability in the level of protein found to be optimal suggests that differences in the amino acid composition of the rations fed may be responsible for the discrepancies in the protein levels recommended by different investigators. Depending upon the grain used in formulating laying rations of a certain protein content, the proportion of supplementary protein to cereal protein may vary considerably. As a consequence wide differences in amino acid balance may be encountered even in rations of similar protein content. The following experiment was designed to determine if a laying ration containing 70 percent of wheat and supplying a total of 14 percent protein from plant sources is adequate for…

FOLLOWING discovery of the growth-stimulating properties of dietarily administered antibiotics for the chick, it was reported that the growth response may be due, in some instances, to a sparing effect on the dietary requirement for vitamins of the B-complex (Biely and March, 1951). There are numerous reports in this regard pertaining to other animals as well as the chick. Combs (1955) has tabulated the results obtained with chicks published by different investigators. Although the concept that antibiotics may have a sparing effect on dietary vitamin requirement has been generally upheld, the findings are not consistent as to which vitamins are spared and which are not. The following experiments were conducted in an attempt to determine the reason or reasons for the discrepancies in the response to antibiotics of chicks fed diets deficient in different vitamins of the B-complex. The experiments were carried out over a period of four years to …

KUMMEROW, Weaver and Honstead (1949) found that the addition of high levels of fat to the diet increased the requirement of the chick for choline. Siedler and Schweigert (1953), on the other hand, observed no gain from choline supplementation of diets containing from 2 to 8 percent of added fat. Frazer (1946) and Tidwell (1950) reported that choline accelerated absorption of fat in the rat. The data in the literature indicate that choline requirement is not always raised by increasing the dietary fat level; nevertheless, there is often an effect in this direction. Because of the recognized interrelationship among choline, folacin, vitamin B12 and methionine, it seemed possible that contradictory evidence regarding the effect of dietary fat on choline requirement may be the result of differences in the composition of the experimental diets. Schaefer, Salmon, Strength and Copeland (1950) and Strength, Schaefer and Salmon (1951) demonstrated an interrelationship between the …

Experiments were conducted to study the metabolizable energy (M.E.) value of rapeseed meal for chickens of different ages. Using laying pullets of three genetic sources, average M.E. values of 2390, 2570 and 2710 cal./gm. were obtained for one sample of rapeseed meal. Three-week old chicks gave an M.E. value of 1465 cal./gm. for the same meal. In another assay, the M.E. value of a second meal was estimated to be 2020 and 1510 cal./gm. for laying pullets and 3-week old chicks respectively. M.E. values of diets containing soybean or one of five different rapeseed meals were determined weekly with chicks to 5 weeks of age. The M.E. value of the soybean meal diet remained relatively constant over the period, whereas M.E. values of the rapeseed meal diets progressively declined to approximately 92% of the values estimated at 1 week of age.

STANDARDIZATION of techniques for measuring protein quality is difficult because of many interacting factors. The choice of breed or strain of bird may have a bearing upon the response to a given source of protein since there are genetic differences in the amino acid requirements of the chick. For example, breed and strain differences have been demonstrated in the requirement for methionine and cystine (MacDonald, 1958; Miller et al., 1960); arginine (Hegsted et al., 1941; Nesheim and Hutt, 1962); and lysine (Griminger and Fisher, 1962). In a collaborative study March et al. (1965) compared the relative rates of growth of chicks fed diets composed of different grains and protein concentrates at different locations and with chicks of different genetic background. It was found that when the differences in amino acid balance of the diets tested were marked the differences in growth response were consistent. When, however, differences in amino acid…

THE mechanisms whereby hypo-or hypercholesterolemia is induced by the dietary fats fed in cholesterol-free diets are not completely understood. The effects of fats on blood cholesterol level may be related to differences in the rates of bile acid excretion induced by the fats. Gordon et al. (1957); Byers and Friedman (1958); Haust and Beveridge (1958); Srikantia and Gopalan (1960); Goldsmith et al. (1960); Moore et al. (1962); have all shown that unsaturated fats which reduce blood cholesterol levels also increase excretion of bile acids. On the other hand, Avigan and Steinberg (1965); Lindestedt et al. (1965); Grundy et al. (1965); Ali et al. (1966); found no significant differences in bile acid excretion when fats of different degrees of saturation were fed. The above reports pertained to studies with human subjects, rats or rabbits. Comparatively few studies have been made of bile acid excretion in the chicken despite the considerable use…