Submaintenance Levels Research Articles

Spatial and Temporal Consumption Dynamics of Trout in Catch‐and‐Release Areas in Arkansas Tailwaters

AbstractRestrictive angling regulations in tailwater trout fisheries may be unsuccessful if food availability limits energy for fish to grow. We examined spatial and temporal variation in energy intake and growth in populations of Brown Trout Salmo trutta and Rainbow Trout Oncorhynchus mykiss within three catch‐and‐release (C‐R) areas in Arkansas tailwaters to evaluate food availability compared with consumption. Based on bioenergetic simulations, Rainbow Trout fed at submaintenance levels in both size‐classes (≤400 mm TL, >400 mm TL) throughout most seasons. A particular bottleneck in food availability occurred in the winter for Rainbow Trout when the daily ration was substantially below the minimum required for maintenance, despite reduced metabolic costs associated with lower water temperatures. Rainbow Trout growth rates followed a similar pattern to consumption with negative growth rates during the winter periods. All three size‐classes (<250 mm TL, 250–400 mm TL, >400 mm TL) of Brown Trout experienced high growth rates and limited temporal bottlenecks in food availability. We observed higher mean densities for Rainbow Trout (47–342 fish/ha) than for Brown Trout (3–84 fish/ha) in all C‐R areas. Lower densities of Brown Trout coupled with an ontogenetic shift towards piscivory may have allowed for higher growth rates and sufficient consumption rates to meet energetic demands. Brown Trout at current densities were more effective in maintaining adequate growth rates and larger sizes in C‐R areas than were Rainbow Trout. Bioenergetic simulations suggest that reducing stocking levels of Rainbow Trout in the tailwaters may be necessary in order to achieve increased catch rates of larger trout in the C‐R areas.Received August 31, 2016; accepted January 9, 2017 Published online March 21, 2017

Potential benefit of trace element supplementation of sheep on a low level of nutrition

A study was conducted to test whether supplementation of trace elements would have any beneficial effect on year-old ewes receiving a submaintenance level of nutrition. The ewes were fed a poor quality hay. The control group received no supplementation (Treatment 1). A solution containing copper (Cu, 5 mg/d), selenium (Se, 1.6 mg/d) and zinc (Zn, 48.2 mg/d) was dosed twice a day to sheep in Treatment 2 while the ewes in Treatment 3 received a double dose of the three elements. Tissue analyses at the end of the 93-day experimental period suggested that the lambs in the control group suffered from a marginal Se deficiency, while the intake of the other elements seemed to be sufficient. Within treatments, weight changes varied tremendously. Therefore, even though differences were not significant, the unsupplemented control group lost weight, while the sheep in the other two treatments maintained their initial body weights during the study. Likewise, the control group tended to have a lower immune response against an injected foreign protein than the supplemented treatments, though differences were not significant. Plasma in the control group showed significantly higher activities of creatine phosphatase and aspartate transaminase than the supplemented groups. This suggested that the supplemented elements protected the body against tissue damage. Although it is traditionally considered that deficiencies in energy and protein, as first limiting nutrients with the highest priority in nutrition, should be overcome before any response to trace element supplementation could be expected, many of the micronutrients are involved in antioxidant activities in the body. Results from this study suggested that positive responses to micronutrient supplementation could be possible if the body is subjected to oxidative stress during submaintenance levels of energy and/or protein nutrition. South African Journal of Animal Science Vol. 36(1) 2006: 20-27

The influence of body condition and level of feeding on the heat production of nonpregnant, nonlactating dairy cows

Chowdhury and Ørskov (1994) observed that heat production in sheep was reduced by approximately 10% below that at fasting when the animal was offered one third of the predicted maintenance requirement through intragastric nutrition. These authors also suggested that this indicated a glucose deficient state in the fasted animal, and that as a result the heat production at fasting was artificially raised. In agreement with Ørskov and MacLeod (1990), Chowdhury and Ørskov (1994) further stated that when measuring heat production to estimate basal metabolism animals should have their heat production measured when being offered one third of maintenance rather than fasting, although this was not tested by experiment. Birnie et al., (2000) reported that fasting heat production was influenced by the condition score of the cow. The objectives of this experiment were firstly to investigate the influence of maintenance and sub-maintenance levels of feeding on the observed heat production in nonpregnant, nonlactating dairy cows offered a more normal diet and secondly to further examine the influence of cow condition score on the fasting heat production.

Protein and sulphur amino acid nutrition of hair fibre-producing Angora and Cashmere goats

The results from a number of studies are presented which investigated responses in fibre production of British Cashmere and Angora goats to variation in protein and sulphur amino acid nutrition under conditions of active fibre growth. Requirements for amino acids were considered in the context of the concentration of amino acids, including cysteine and methionine, in rumen microbial protein and in dietary protein supplements compared with the amino acid composition of hair fibre. Increases in fibre yield and diameter were consistently observed in Angora goats given good quality protein supplements or rumen-protected intestinally-available methionine (Smartamine™M, Rhône-Poulenc). Cashmere yield was not influenced by urea or white fishmeal supplementation but responded positively (in contrast to other studies in the literature) to additional dietary methionine. While responses in cashmere production have been recorded in response to protein supplementation at sub-maintenance levels of nutrition, it is suggested that one component of the absent or reduced response at above maintenance may be the smaller quantitative synthesis of this fibre compared with mohair production by Angora goats. The results are considered in the context of studies from the sheep literature in which protein and amino acid supplementation were shown to stimulate proliferation of hair forming cells in the wool follicle and to increase deposition of protein fractions containing high concentrations of sulphur-containing amino acids. Results from an in vitro study suggested that methionine could support cashmere fibre growth (approximately 0.75) in the absence of cysteine and cystine, providing evidence that methionine is essential for fibre production and that transulphuration occurs in isolated hair follicles. However, cysteine and cystine were also required to produce maximum growth. In the context of competition between the hair follicle and other body tissues, data are presented which illustrate the increases in nitrogen retention and/or anabolic growth response to protein or protected-methionine supplementation in non-integumental tissues of Cashmere and Angora goats also, despite the presence of lower concentrations of sulphur-containing amino acids in these tissues. The results confirm the value of a good quality protein supplement or more targeted supply of rumen-protected intestinally-available methionine to correct a frequently apparent deficiency in sulphur amino acid supply for (a) growth of hair fibre by Angora goats and, less consistently, by Cashmere goats and (b) other body tissues in both genotypes.

Effect of the β-adrenergic agonist cimaterol and dietary protein level on fat young sheep given diets containing submaintenance levels of dietary energy

AbstractThirty Suffolk cross wether sheep aged about 12 months and weighing 57 kg on average were used. They had been given previously a high energy diet to produce a fat body condition and average condition score of 3·7. Animals were allocated to an initial slaughter group (IS) or to four dietary treatment groups (UL, UH, CL and CH) based on sugar-beet feed (L) or white-fish meal (H) supplemented with chopped straw and pelleted, without (UL and UH) or with (CL and CH) the β-adrenergic agonist cimaterol, to provide an estimated 20 g (L) or 130 g (H) rumen undegradable protein per kg dry matter (DM). The sheep were offered 0·3 kg of the appropriate pelleted diet in addition to 200 to 400 g of chopped barley straw to provide proportionately 0·7 of the estimated metabolizable energy requirement for maintenance and, where appropriate, 2·5 mg cimaterol per day. Comparisons were made for the main effects of dietary protein intake and cimaterol and interactions between dietary protein and cimaterol.The animals on dietary treatments were slaughtered after 49 days. The animals exhibited variable reductions in live weight and weights of carcass and non-carcass components in comparison with the IS group and in response to restricted dietary energy intake. The only effect due to the elevated dietary protein provision was a smaller loss in live weight compared with the low protein diet. In contrast, compared with responses recorded in its absence, treatment with cimaterol resulted in significantly greater values for weights of cold carcass, cross-sectional area o/m. longissimus dorsi and weights of DM, crude protein and ash in the carcass with significantly smaller weights for raw fleece. In comparison with the IS group, significantly smaller changes due to cimaterol were recorded for the weights of carcass crude protein and ash. Cimaterol treatment significantly increased the weight loss of fat in the carcass and in the perirenal and retroperitoneal, but not omental, depots as components of fleece-free non-carcass fat which was also significantly reduced in total. Interactions suggested that losses in carcass weight and DM in the presence of cimaterol were less and gains in carcass protein and ash greater, on the high than on the low protein diet. The results suggest that under conditions of energy undernutrition cimaterol may induce smaller losses or larger gains in carcass but not non-carcass, crude protein at the expense of fat depletion in carcass and non-carcass fat depots.

Effect of a Daily Supplementation of Polyethylene Glycol on Intake and Digestion of Tannin-Containing Leaves (Quercus calliprinos, Pistacia lentiscus, and Ceratonia siliqua) by Goats

Intake and digestion of leaves of Quercus calliprinos, Pistacia lentiscus, and Ceratonia siliqua, with and without supplementation of various amounts of polyethylene glycol (PEG), were examined. The tannin contents in these species exerted a substantial negative effect on feed intake and digestion. The effects were species specific and related to tannin content. Once-daily Supplementation with PEG efficiently neutralized the negative effects of tannins. The amount of PEG needed to produce a maximal increase in feed intake was lower than the amount required to produce a maximal increase in digestibility. The intake of digestible crude protein and metabolizable energy was raised in PEGsupplemented animals from a submaintenance level to levels considerably exceeding the maintenance requirement of goats. The response was related to the tannin content of the plant.

Examination of energy utilization in cattle offered a forage diet at near- and sub-maintenance levels of feeding.

Eight Friesian calves were reared from birth to the start of the experiment at a predetermined growth rate of 1.0 kg/d. Four calves (group 1) commenced the experiment at 22 weeks of age and the remainder (group 2) at 34 weeks, and feed intake was calculated to provide sufficient metabolizable energy to sustain zero energy balance (Em). Between experimental days 30 and 56 at maintenance levels of feeding, respiratory exchange measurements were made using open-circuit calorimetry to provide indirect estimates of heat production (H) simultaneous with measurements of faecal and urinary excretion of energy and N. A datum point for Em and H was established for each animal giving mean values for Em of 491 and 537 and for H of 476 and 511 kJ/kg live weight (LW)0.75 per d for groups 1 and 2 respectively. Treatment levels calculated as 0.25, 0.5, 0.75 and 1.25 of dry matter intake required to sustain the measured Em, were imposed on individual animals after day 56 and further measurements of H and faecal/urinary balance were made between days 72 and 84 followed by measurements of fasting heat production (FHP) during days 86-90 from the two animals in each group which had received the 0.75 and 1.25 levels of intake. Regression analysis of the treatment levels indicated separate linear models which predicted Em at 419 and 473 kJ/kg LW0.75 per d for groups 1 and 2 respectively. The incorporation of FHP with partitioning of faecal and urinary energy losses measured during fasting altered the relationship but not the predicted Em. Overall predicted Em (days 72-84) from all models were 406 and 478 kJ/kg LW0.75 per d for groups 1 and 2 respectively which were significantly lower (P < 0.05) than Em measured during days 30-56.

Effects of energy or protein restriction on weight and composition of diabetic and control rats

Adult (170 ± 1 g) male Sprague-Dawley diabetic (50 mg/kg of streptozotocin) and control rats were fed for 21 days a diet with adequate protein (28%) at three restricted levels of intake (34, 45 or 57 kcal/day), or were fed at a single level of intake (ad libitum) diets containing different percentages of protein (2.25, 5.5 and 11.1). When dietary protein was adequate (28%), but energy intake was severely restricted (34 kcal/day), diabetic and control rats lost 80 ± 5 and 100 ± 6 g/kg 0.75 in body weight, respectively. Diabetic and control rats lost 110 ± 4 and 139 ± 7 g/kg 0.75 in body weight, respectively, when energy was unrestricted and dietary protein was at a submaintenance level (2.25%). Body weight of diabetic and control rats did not differ when dietary protein was adequate (28%) and energy intake was moderately restricted (45 kcal/day) or when energy intake was unrestricted and dietary protein was at a maintenance level (5.5%). This study showed that diabetic rats fared as well as or better than their control counterparts when the intake of either energy or protein was moderately or severely restricted.

Growth of the Earthworm Eisenia Foetida in Relation to Population Density and Food Rationing

At 250C Eisenia foetida hatches from its cocoon about 3 weeks after fertilization and follows a logistic growth pattern. It grows slowly for about three weeks and then enters a rapid phase whose slope is useful as an index to the nutritional quality of its food. The rapid phase is followed by a steady state maintenance phase, or by a phase of weight decline whose slope can be used as an index to a property of the food which is related to starvation latency. The slope of the rapid phase for individually grown worms was steeper on activated sludge than on cow manure and steeper on the latter than on horse manure. The maximum weight achieved by individually tested E. foetida was significantly greater with activated sludge than with either manure as food. The manures provided nutrients at a rate suboptimal to genetic capability for growth but either served as a better source of food than sludge when submaintenance levels remained, or were less toxic as castings. In a volume of about 30 cc over an area 78 cm2 the carrying capacity of 250 g horse manure on 50 g silt loam was 6 g live weight E. foetida; this value for these periodically disturbed systems is considerably less than what can be achieved in undisturbed systems published elsewhere. Carrying capacity was not achieved in the same volume-area-time relation with activated sludge in place of manure, though more than 23 g could be supported; more than ten times as much biomass of E. foetida can be supported per unit area of soil overlain by activated sludge than has been reported for earthworms in natural ecosystems.

Protein Requirements of Man: Efficiency of Egg Protein Utilization at Maintenance and Sub-maintenance Levels in Young Men

The purpose of these studies was to evaluate the assumptions made in estimating minimum protein requirements by the factorial method. A series of nitrogen (N) balance experiments were conducted with young male M.I.T. students given egg protein at or below their maintenance requirements. Data from previous studies are also included, involving a total of 107 subjects with 131 separate balance periods. In a few subjects, measurements were also made of urinary urea and creatinine and of various serum constituents, including acidic and neutral free amino acid levels, in blood samples drawn after an overnight fast and 3.5 to 4 hours after breakfast. The significance of the amino acid changes with alterations in egg protein intake is discussed in relation to the requirements for essential amino acids. The efficiency of egg protein utilization was not constant throughout the submaintenance range of protein intake; the overall N balance data showed a curvilinear decrease as protein intake approached maintenance levels. By regression analysis, the mean requirement for egg protein N in young men was estimated to be 73 mg N/kilogram body weight/day, the 95% confidence interval falling between 60 and 94 mg N/kilogram body weight. These results also indicate that the evaluation of dietary protein quality in adult man should be carried out at more than one level of protein intake.

Energy balance studies with weaned lambs

Abstract A study was made of the efficiency of utilisation of lucerne by lambs weaned at 5 weeks of age. The comparative slaughter method was used to determine the gain or loss in body fat, protein, and energy. Nineteen crossbred lambs were used; 12 comprised an initial slaughter group and the remaining lambs were given fresh lucerne for 26 days at various levels of energy intake ranging from sub-maintenance to ad libitum. All lambs mobilised fat and were in negative energy balance. Only the lamb on the sub-maintenance level of nutrition was in negative nitrogen balance. The mean digestibility of the lucerne was 69.%, the mean metabolisability of the diet was 53.9%. At a given body weight, lambs fed on lucerne had more protein and less fat than those in the initial slaughter group. The metabolisable energy requirement for zero energy gain was 191.4 kcals/kgv? 24 hr, and the efficiency of utilisation of metabolisable energy for maintenance was 47.1%.

Environmental temperature and the energy metabolism and heat emission of steers

1. The energy metabolism and heat emission of two steers was determined at the maintenance level of nutrition in an environment of – 5, 5, 15, 25 and 35° C. and at a submaintenance level of nutrition in environments of – 5 and 19° C.2. Shivering was observed at temperatures of – 5 and + 5° C. in both animals. Respiratory distress occurred at 35° C. being more severe in one animal than in the other. The animals stood for longer periods at the extreme temperatures.3. The digestibility of food increased slightly as environmental temperature increased. Losses of energy as methane and in urine did not change in response to environmental temperature.

The effect of environmental conditions on food utilisation by sheep

1. A series of calorimetric experiments was conducted with sheep which had fleeces ranging in thickness from 0·1 cm. to 12 cm. at environmental temperatures between 8 and 32° C. Heat production, heat loss by radiation, by convection and conduction, by vaporisation of water and due to warming food and water to body temperature were measured together with losses of energy in faeces, in urine and as methane.2. The effects of a rise in environmental temperature on digestion of the food and on the loss of energy in urine or as methane resulted in a slight rise in the metabolisable energy of the ration by 6 Cal./° C.3. Environmental temperature had a marked effect on heat production, particularly when the fleece was short. The critical temperature (i.e. the environmental temperature at which heat production was minimal) of the closely-clipped sheep varied from 24° C. at a high level of feeding to 38°C. at a sub-maintenance level of feeding. These critical temperatures are similar to that of naked, resting man but much higher than that of the pig when fed similarly.4. As the fleece grew the critical temperature fell. Thus, on a maintenance level of feeding, a sheep with a fleece of 0·1 cm. had a critical temperature of 32° C.; when the fleece had grown to 2·5 cm. the critical temperature was 13° C. while with a 12 cm. fleece the critical temperature was 0° C.5. Below the critical temperature heat losses increase more rapidly in sheep with light fleeces. Thus a heavy fleece not only depresses the critical temperature but also reduces the rate of increase of heat loss with falling temperature under sub-critical conditions.6. At environmental temperatures well below the critical, the heat losses of the sheep per unit surface were identical. Under such conditions, when the whole of the metabolisable energy of the food is used to keep the animal warm, the criterion of ration adequacy is a high content of meta-bolisable energy in small bulk.7. At environmental temperatures above 32° C. the heat production on a constant ration increased, the rise being greatest with the highest level of feeding. Consequently the net energy value of the food declined at these high environmental temperatures.8. The calorimetric experiments were supplemented by two comparative feeding trials in which the effects of normal outdoor environmental conditions on the body weight of groups of Cheviot and Blackface sheep were measured. Control groups were kept indoors in heated pens.9. During the mild winter of 1956-7 the out-wintered Blackface wethers i n full fleece did not loose any more weight than those fed the same rations indoors.10. During the more severe winter of 1957-8, Cheviot, in-lamb ewes kept on a maintenance diet gained 2·3 lb.; those kept outside on the same ration lost 3·3 lb. With Blackface, in·lamb ewes the difference between the two groups was 0·3 lb. in favour of the indoor group.11. The food utilisation of sheep is affected considerably by environmental conditions. With little fleece the critical temperature is high and even when in full fleece an effect of cold can be demonstrated under practical conditions.