Digestion and nitrogen metabolism in sheep and red deer given large or small amounts of water and protein

Diet composition and selection of Père David's deer in Hubei Shishou Milu National Nature Reserve, China

Hubei Shishou Milu National Nature Reserve is an ideal place to restore the wild population of Père David's deer (Elaphurus davidianus). Understanding foraging ecology and diet composition is essential for assessing population development or establishing long-term effective conservation measures for endangered species. However, little is known about the diet composition of Père David's deer and its diet selection mechanism. In this study, we used stable isotope technology to investigate the diet composition of Père David's deer according to various tissues (i.e., fur, muscle, liver, heart, and feces) and seasons, and evaluated the correlation between the nutrient composition of plants and diet composition. Bayesian isotope analysis showed that the autumn and winter diet estimated by fur and fecal samples indicated a diet dominated by C3 grasses (42.7%-57.2%, mean), while the summer diet estimated by muscle and liver samples was dominated by C3 forbs (30.9%-41.6%, mean). The Pearson correlation test indicated that the contribution of winter diet composition reflected by fur and fecal samples was associated with correlations with crude protein (r = .666, p < .01) and soluble sugars (r = .695, p < .01). The results indicated that crude protein and soluble sugars were important factors influencing the winter diet selection of Père David's deer. In the context of the current reintroduction facing many challenges, such as habitat fragmentation, wetland degradation, and human disturbance, comprehensively evaluating the diet selection mechanism of Père David's deer under different resource specificities and temporal changes should be considered in the future.

Effect of feeding supplements on the intake and live-weight gain of male red deer given silage during winter

The live-weight gain (LWG) of young male red deer in New Zealand naturally slows during winter and feeding diets of mainly silage appears to exacerbate this effect. We aimed to quantify the effect of feeding silage on intake and LWG during winter and the ability to improve LWG by feeding supplements, mainly in the form of barley. Seven groups of eight deer were maintained outside in gravelled enclosures and offered silage ad libitum for 94 days during winter. Six groups were given supplements (950 g barley with 50 g rapeseed meal per kg to make all diets isonitrogenous) at rates of proportionately 0·2, 0·4, 0·5, 0·6, 0·7 and 0·9 of the metabolizable energy (ME) intake of the group given only silage (0). The study also examined the effect of the winter treatments on subsequent LWG to slaughter weight whilst grazing on pasture during spring and into summer (102 days).

Increasing supplement intake resulted in a decrease in silage dry matter (DM) and ME intake (P < 0·001) and an increase in total ME intake (P < 0·01). The substitution rate for silage DM was 0·84 (s.e. 0·079). LWG during silage feeding was positively related (P < 0·01) to supplement intake with an increase of 6·21 g/day per MJ per day. LWG on pasture was not related to either supplement feeding rate or LWG during winter. LWG over the entire experiment was related (P < 0·01) to supplement feeding rate, with a final difference in live weight of 6 kg between 0 and 0·9 groups.

This study has confirmed that the LWG of young male deer is low during winter when given only silage and that feeding supplements increases total ME intake and LWG. The reduced LWG due to silage feeding was not compensated for on pasture during spring and summer, thus delaying the time to reach slaughter weight by approximately 1 month. High proportions of silage in the diet appear unsuitable for young male deer if the aim is to achieve rapid LWG during winter.

Maintenance Crude Protein Requirement of Penned Female Korean Spotted Deer (Cervus nippon)

This study was conducted to evaluate the protein requirement for maintenance of 2-year-old female Korean spotted deer. In the course of the experiment, each of three hand-reared female spotted deer was fed three diets that were iso-calorically formulated to contain low (approximately 7%), medium (12%), and high (17%) levels of crude protein (CP). Each of six trials included a 5-day transition, a 10-day preliminary, and a 7-day collection period. Dietary protein levels affected the apparent digestibility of CP (p<0.05) but not the apparent digestibility of dry matter, organic matter, or acid detergent fiber. All of the deer showed a positive CP balance on all of the diets. The maintenance CP requirement estimated by regression analysis was 4.17 g/kg metabolic body weight (W^0.75)·d. The maintenance digestible CP requirement was 1.42 g/kg W^0.75·d. The metabolic fecal CP was 1.95 g/kg W^0.75·d. The blood urea nitrogen of spotted deer increased (p<0.05) as the dietary protein levels increased.

Metabolism of microbial nitrogen in ruminants with special reference to nucleic acids

Characteristically the metabolism of microbial nitrogen (N) compounds in ruminants involves the degradation of dietary N and synthesis of microbial protein (MP), compounds including a small amount of peptides and free amino acids, which may account for 75-85% of total N and the remainder are nucleic acids (NA: DNA and RNA). Generally rumen microbes contain 10-25% NA-N of the total N while 70-80% is in the form of RNA. This paper describes the degradation and synthesis of NA in the rumen and their fate in the lower digestive tracts. Their physiological and nutritional significance in different types of ruminant animals is also discussed. The research works on NA metabolism in ruminants has been mainly on metabolism of purines after rumen microbial digestion and absorption in the lower gut. Subsequently, the fate of absorbed purines has been intensively investigated to assess the extent of MP synthesis in the rumen. The method for predicting ruminal synthesized MP and subsequently digested MP has been proposed using urinary purine derivative (PD) excretion in sheep and cattle fed on ordinary feed. The latter approach has now been adopted for calculation of protein supply in some feeding standards, although there are still difficulties in predicting representative samples of rumen microbes, and also uncertainties in variations of non-renal and endogenous purine losses.

Some effects of handling reindeer during gatherings on the composition of their blood

1. The effect of gathering reindeer on the composition of the blood was studied in female reindeer and their calves herded in northern Finland. Blood samples were taken in summer at three gathering places, under differing conditions and in autumn at the same places during gatherings which lasted for longer than 2 days. These were compared with samples taken from little-disturbed animals during winter.

2. Measurements were made of concentrations of glucose and lactate in whole blood and of urea, calcium, sodium, potassium and magnesium in serum, together with serum creatine phosphokinase (CPK) and glutamine oxalacetic transaminase (GOT) activities.

3. Gatherings affected nearly all the blood parameters studied. In summer the temperature during separation seemed to influence glucose and lactate concentrations. The duration of the gathering and the distance the animals were driven clearly affected serum GOT and urea values.

4. During the long autumn gathering serum urea concentration increased about eight-fold in 2 days accompanied by a simultaneous decrease in serum calcium.

5. Serum CPK and GOT activities were higher during the summer and autumn than during the winter. Serum CPK and blood glucose concentrations were higher in young calves than in adult females.

Effects of water and feed restriction on body weight change and nitrogen balance in desert goats fed high and low quality forages

The effects of water and food restriction on feed utilization, body weight changes and nitrogen balance were investigated in Sudanese desert goats given high or low quality forage. Nine male goats were employed in a 3x3 Latin square design where they were subjected to three treatments: ad libitum water and feed, ad-libitum feed/restricted water, and ad libitum water/restricted feed. These treatments were repeated using lucerne or sorghum hay. For both feed types dry matter intake (DMI) was not affected by treatments. Water intake decreased with feed restriction in goats fed sorghum hay. The ratio of water intake to DMI increased with lucerne hay compared to sorghum hay in both the control and feed restricted group. Water consumption increased with lucerne compared to sorghum hay. Body weight losses were more pronounced with water than with feed restriction but were less severe with lucerne than sorghum hay. Interactions due to treatment and feed type were significant for water intake and body weight change. With lucerne hay, except for crude protein (CP), nutrient digestibility improved with water restriction. Feeding sorghum hay, there were no effects on digestibility except for crude protein (CP) that was reduced with water restriction. Crude fiber (CF) and nitrogen free extract (NFE) digestibility increased with feed restriction in animals on sorghum hay. For all groups, CP digestibility was better with lucerne than sorghum hay. Interactions of the main effects were significant for all apparent digestibility coefficients as well as total digestible nutrients. The treatments did not have significant effects on nitrogen balance, however, nitrogen intake, retained or excreted in faeces was higher with lucerne than sorghum hay. It may be concluded that subjecting animals to water or feed restriction will have a more deleterious effect on feed utilization and nitrogen balance when using a low than a high quality forage.

Prolonged winter undernutrition and the interpretation of urinary allantoin:creatinine ratios in white-tailed deer

The urinary allantoin:creatinine (A:C) ratio (expressed in micromoles of allantoin to micromoles of creatinine) has shown potential as an index of recent winter energy intake in preliminary controlled studies of elk (Cervus elaphus) involving mild condition deterioration (up to 11% loss of body mass). To ensure reliable nutritional assessments of free-ranging cervids by measuring A:C ratios of urine in snow, it is essential to extend this work. We assessed the effect of moderate and severe winter nutritional restriction on urinary A:C ratios of captive white-tailed deer (Odocoileus virginianus) that lost up to 32% body mass and related these ratios to metabolizable energy intake (MEI), body-mass loss, and other reported nutritional indicators. Deer in the control group were fed a low-protein, low-energy diet ad libitum, whereas deer in the treatment group were fed restricted amounts of the same diet. MEI was below the winter maintenance requirement for all deer, but was lower (P = 0.029) in treatment deer than in control deer. Percent body-mass loss differed between the two groups as the study progressed, and represented the full range of physiological tolerance (0-32% loss). Mean A:C ratios of control deer, which lost up to 17.4% body mass, showed a slight increasing (P = 0.086) trend, whereas initially similar A:C ratios of severely restricted deer increased (P = 0.0002) markedly by the eighth week (0.52 vs. 0.09 µmol:µmol). The urinary A:C ratio was not related (P = 0.839) to recent (2 days prior to urine sampling) MEI, but there was a marginally significant relation (r2 = 0.42, P = 0.110) between the A:C ratio and cumulative percent mass loss. The urinary A:C ratio was directly related to urinary urea nitrogen:creatinine (r2 = 0.59, P < 0.0001) and 3-methylhistidine:creatinine (r2 = 0.43, P < 0.0001) ratios. This study confirms that elevated and increasing A:C ratios may be due either to increasing energy intake or to accelerated tissue catabolism and increased endogenous contributions to urinary allantoin excretion.

Urinary excretion of purine derivatives and tissue xanthine oxidase (EC 1.2.3.2) activity in buffaloes (Bubalis bubalis) with special reference to differences between buffaloes and Bos taurus cattle

The urinary excretion of purine derivatives (PD) was measured in six buffaloes (Bubalis bubalis) during fasting and in fourteen buffaloes given four restricted levels of roughage (2.5-4.8 kg DM/d). Only allantoin and uric acid, not xanthine and hypoxanthine, were present in the urine, the pattern of excretion being similar to that in cattle. The fasting PD excretion amounted to 0.20 (SD 0.06) mmol/kg metabolic weight (W)0.75 per d, and the rate of PD excretion as a linear function of feed intake was 5.2 mmol/kg digestible organic matter intake. Both values were considerably lower than the values for cattle reported in the literature. Creatinine excretion values were 0.33 (SD 0.06) and 0.44 (SD 0.09) mmol/kg (W)0.75 per d determined in fasting and feeding periods respectively. Fasting N excretion was 257 (SD 49) mg N/kg (W)0.75 per d. Both creatinine and fasting N excretions were also lower than in cattle. The activities of xanthine oxidase (EC 1.2.3.2) in plasma, liver and intestinal mucosa were determined in buffaloes, cattle and sheep. Xanthine oxidase activities in buffaloes were 24.5 (SD 2.7) unit/l plasma and 0.44 (SD 0.02) and 0.31 (SD 0.10) unit/g fresh tissue in liver and intestinal mucosa respectively. These activities were higher than those in cattle and sheep. Xanthine oxidase was practically absent from plasma and intestine of sheep. It is suggested that the differences in PD excretion between buffaloes and cattle were probably due to the smaller proportion of plasma PD that was disposed of in the urine of buffaloes.

Rumen digestion and urinary excretion of purine derivatives in response to urea supplementation of sodium-treated straw fed to sheep

The present study examined the effect of urea-N supplementation of a N-deficient diet on digestion and metabolism in the rumen. Five Rasa Aragonesa ewes, each fitted with a rumen cannula, were offered alkali-treated barley straw ad lib. alone or supplemented continuously via the cannula with four levels of urea-N (3, 6, 9 and 12 g/d). Rumen NH3 concentrations increased in response to urea infusion (6-128 mg/l; P < 0.001). At the highest level of rumen NH3 concentration there was a significant increase, compared with the unsupplemented treatment, in dry matter (DM) intake (846-1206 g/d; P < 0.001) and apparent digestibility of DM (0.38-0.43), organic matter (0.38-0.45) and neutral-detergent fibre (0.41-0.49; P < 0.01). Rumen outflow rates of particulate matter and potential DM disappearances, assessed using nylon bags, were not affected by the experimental treatments, although fractional rate of DM disappearance increased significantly with increasing levels of urea infusion (2.4-4.6 per h). Urinary excretion of total purine derivatives increased with N supplementation, although the response was exclusively due to an increase in allantoin excretion (26.9-66.4 mg/kg live weight (W)0.75 per d; P < 0.001). Xanthine, hypoxanthine and uric acid excretion rates were constant, averaging 1.8 (SE 0.17); 5.4 (SE 0.21) and 7.2 (SE 0.36) mg/kg W0.75 per d respectively. The maintenance of a minimum rumen NH3 concentration (approximately 50 mg/l) was necessary to avoid significant reductions in DM intake and fermentation rate. Higher levels, however, may further increase microbial N flow at the duodenum, as suggested by the response in urinary allantoin excretion over the range of rumen NH3 concentrations.

Seasonal and nutritional effects on serum proteins and urea concentration in the reindeer (Rangifer tarandus tarandus L.)

1. The effects of seasonal conditions and nutrition on serum proteins and serum urea concentrations were studied in female reindeer and reindeer calves in Finland. With the exception of one group in winter, the reindeer were roaming wild in the forests. This one group was kept in captivity, out of doors, on a comparatively high nutritional plane. One group lived wild during the winter in very poor nutritional conditions. 2. A very clear seasonal variation in the serum protein and urea concentration was found. The serum protein concentration was low in late winter and increased rapidly during the summer, being high in the autumn. The serum urea concentration was also low in the winter and high in the summer. In the autumn, however, the serum urea concentration was again low. 3. Changes in the serum protein concentration were normally associated with the serum globulins. Only in the very poor-nutrition group did the albumin content decrease significantly. As a result of the large changes in the concentration of serum globulins, there were also considerable changes in the albumin: globulin ratio. 4. The serum protein concentration was much lower in the reindeer calves than in the adult reindeer. The concentration of globulins in particular was much lower than in the adults.