Effects of a high NaCl diet on eating and drinking patterns in pygmy goats

Water Quality for Grazing Livestock I

Water is the most important nutrient for rangeland livestock. However, competition with municipalities, industry, and other water users often results in grazing livestock being forced to use water supplies that are less than perfect. Surface water in western rangleands are often contaminated by mineral extraction, irrigation runoff and other human activities. Mineral contaminants in drinking water are additive with similar contaminants in feedstuffs. The goal of this and the subsequent article is to provide producers and veterinarians with the basic background to make informed decisions about whether a given water supply is "safe" for livestock.

Effects of level of brackish water on feed intake, digestion, heat energy, and blood constituents of growing Boer and Spanish goat wethers

Twenty Boer (6.1 mo old and 21.3 kg) and 20 Spanish (6.6 mo old and 19.7 kg) goat wethers were used to determine effects of brackish water on feed intake, digestion, heat energy, and blood constituents. Brackish water had 6,900 mg/L total dissolved salts, 1,885 mg/L Na, 75 mg/L Mg, 1,854 mg/L chloride, 2,478 mg/L sulfate, and 9 mg/L boron. Water treatments were 100% tap water (control), 100% of a brackish water source (100-BR), 33% control and 67% brackish water (67-BR), and 67% control and 33% brackish water (33-BR). Water and a moderate-quality grass hay (8.5% CP and 68% NDF) were offered free choice. The experiment consisted of 14 d of adaptation, 5 d for metabolizability measures, and 2 d for determining gas exchange and heat energy. There were no interactions ( > 0.05) between breed and water treatment. Water intake (931, 942, 949, and 886 g/d [SE 59.1] for the control, 33-BR, 67-BR, and 100-BR, respectively) and DM intake (525, 556, 571, and 527 g/d [SE 31.0] for the control, 33-BR, 67-BR, and 100-BR, respectively) were similar among treatments ( = 0.876 and = 0.667, respectively). Urinary water was greater for brackish water treatments than for the control ( = 0.003; 211, 317, 319, and 285 g/d [SE 25.6] for the control, 33-BR, 67-BR, and 100-BR, respectively) and fecal water content was similar among treatments ( = 0.530; 247, 251, 276, and 257 g/d [SE 19.0] for the control, 33-BR, 67-BR, and 100-BR, respectively), implying less water loss by other means such as evaporation when brackish water was consumed. Total tract OM digestibility was lower ( = 0.049) for treatments with brackish water than for treatments without brackish water (64.2, 61.5, 58.6, and 59.3% [SE 1.86] for the control, 33-BR, 67-BR, and 100-BR, respectively), although ME intake was similar among treatments ( = 0.940; 4.61, 4.57, 4.60, and 4.31 MJ/d [SE 0.394] for the control, 33-BR, 67-BR, and 100-BR, respectively). Daily heat energy in kilojoules per kilogram BW was less with brackish water than without brackish water ( = 0.001; 474, 436, 446, and 445 kJ/kg BW [SE 7.7] for the control, 33-BR, 67-BR, and 100-BR, respectively), although values in megajoules were similar among treatments ( = 0.588; 4.36, 4.12, 4.22, and 4.18 MJ [SE 0.124] for the control, 33-BR, 67-BR, and 100-BR, respectively). Body weight of wethers consuming brackish water decreased less than that of wethers consuming the control water ( = 0.006; -37, -14, -7, and -16 g [SE 7.2] for the control, 33-BR, 67-BR, and 100-BR, respectively), but recovered energy was similar among treatments ( = 0.923; 0.25, 0.45, 0.38, and 0.13 MJ/d [SE 0.356] for the control, 33-BR, 67-BR, and 100-BR, respectively). In conclusion, brackish water inclusion in drinking water had a number of effects, but it does not appear that consumption of this source would adversely impact performance of growing meat goats.

Increasing sodium bicarbonate level in high-concentrate diets for heifers. II. Effects on chewing and feeding behaviors

Four Holstein heifers (264 ± 12 kg initial BW) were used in a 4 × 4 Latin square design with 21-day experimental periods to determine the effect of increasing levels of sodium bicarbonate (BICARB) (0%, 1.25%, 2.5% and 5%, of concentrate dry matter (DM) basis) on chewing and feed intake behavior when fed high-concentrate diets. Concentrate (13.41% CP, 13.35% NDF) and barley straw were fed once a day at 0830 h ad libitum. Feed bunks placed on scales and video recording were used to measure 24-h feed intake and chewing behavior, respectively. The patterns of feeding behavior (feed intake, meal size and length) and chewing behavior (eating, ruminating and total chewing) were studied by dividing the day into 12 intervals of 2-h each, beginning at feeding (interval 1 through 12). Number of meals per day and eating rate decreased linearly with increasing buffer level, but meal length increased linearly. No treatment effects were observed in sum of daily meal lengths or average meal size. The treatment × interval interaction was significant on meal size, length and feed intake. The size and length of those meals occurring during the 4 h post-feeding increased linearly. However, meal size tended to decrease in the evening between 8 and 12 h, whereas feed intake decreased linearly from 6 to 10 h and from 12 to 14 h post-feeding. Buffer concentration did not affect the percentage of time spent ruminating, eating or drinking per day but the buffer level × interval interaction was significant. Time spent eating expressed as min per kg of DM or organic matter (OM) intake increased linearly with buffer levels. Proportion of time spent eating increased linearly during the intervals between 0 and 4 h post-feeding. Time spent ruminating decreased linearly during the 2 h post-feeding, and also in the evening from 12 to 14 h, and at night from 18 to 22 h post-feeding, but the effect was quadratic between 8 and 10 h when intermediate buffer levels showed the greatest ruminating time. Time spent drinking decreased linearly from 6 to 8 h but increased during the 2 h following feeding and from 10 to 12 h post-feeding. Daily eating rate and meal frequency decreased linearly as the buffer level increased, but average meal size and daily chewing times were not affected. However, significant time of the day × buffer level interactions were observed for feed intake, meal size and length and chewing behavior.

Relationships between metabolic endocrine systems and voluntary feed intake in Merino sheep fed a high salt diet

Grazing saltbush reduces productivity in sheep mostly because the high salt intake decreases feed intake and challenges the metabolism of the animal. However, little is known of the effect of salt load on the endocrine control systems that regulate voluntary feed intake and metabolism. Plasma concentrations of leptin, insulin and cortisol and blood glucose were monitored in wethers fed for 2 weeks with either a control diet (adequate salt) fed ad libitum, a high salt diet (20% of dry matter) fed ad libitum or a group fed the control diet with an intake restricted to that of the high salt ad libitum group (control pair-fed). High salt intakes reduced voluntary feed intake within 1 day and circulating concentrations of insulin and glucose within 2 weeks. Liveweight and leptin concentrations were not specifically affected by the high intake of salt but decreased in response to the decrease in intake. Cortisol secretion was not affected. Although salt intake had a specific effect on insulin and glucose (over and above the effect of reduced feed intake alone), the reduction in insulin would be expected to increase rather than decrease appetite and feed intake. Therefore, insulin, leptin and cortisol do not appear to play major roles in the control of feed intake in sheep consuming high levels of salt.

Feed intake and production in sheep fed diets high in sodium and potassium

Salinity is a problem facing many crop and livestock producers in southern Australia. One management option is to revegetate with salt-tolerant plants suitable for animal production. These plants are often halophytic shrubs containing up to 30% ash, predominantly as sodium, potassium, or chloride. This experiment examines the consequences of a high intake of sodium and potassium separately or together on feed intake, digestibility, liveweight change, and wool growth. Twelve groups of 6 weaner wethers were allocated to treatments according to a balanced 3 × 4 factorial design with 3 levels of added potassium (0, 0.38, and 0.77 mol/kg DM equivalent to 0, 15, and 30 g/kg DM) and 4 levels of added sodium (0, 0.87, 2.18, and 3.48 mol/kg DM, equivalent to 0, 20, 50, and 80 g/kg DM) as the chloride salts. The treatment diets were fed to sheep for 6 weeks. Increasing sodium in the diet significantly decreased feed intake, digestibility, liveweight gain, and wool growth either as a main effect or through an interaction with potassium. Organic matter intake was reduced from 1.35 kg at the lowest levels of sodium and potassium to 0.67 kg at the highest levels. Comparing the same 2 groups, liveweight gain was reduced from 144 to 0 g/day, organic matter digestibility from 59.1% to 57.3%, and wool growth from 1.21 to 1.04 mg/cm2.day. The response surfaces indicate that production was depressed even at the lower levels of sodium, whereas high potassium depressed intake, digestibility, and liveweight gain at high levels of sodium only. The interaction between sodium and potassium was always negative at high levels of sodium, indicating that manipulation of the proportions of the 2 elements is unlikely to provide benefits for animal production when total salt levels are high. Although wool growth was depressed at high sodium and potassium, the efficiency of wool growth increased from 10.0 to 15.4 g/kg organic matter intake when the lowest and highest levels of the sodium and potassium were compared. This result may present significant opportunities for the use of saline land to grow fine wool.

Research note: Postnatal development of electrolyte transport in calf rumen as affected by weaning time

In a previous study we found a positive correlation between early weaning in calves and morphological parameters which were indicative of ruminal development, i.e. the length and width of the papillae. The objective of the present study was to determine to what extent this observation could be reflected by modulations of absorptive and secretory functions of the rumen mucosa. For this purpose the short-circuit currents (Isc) as a measure of electrogenic net ion fluxes and the transepithelial conductances (G(T)) as a measure of the overall tissue permeability were measured in vitro applying the Ussing-chamber technique. Simultaneously, the unidirectional flux rates of sodium and chloride across rumen wall epithelia were determined in the absence of electrochemical gradients. Under these conditions, significant positive net flux rates (Jnet) clearly indicate active mechanisms for electrolyte absorption. For the experiments 12 male Holstein calves 7 d of age were assigned to three groups of 4 animals each: milk group (I, slaughtered after 6 weeks of age), late weaning group (II, slaughtered after 9 weeks of age) and early weaning group (II, weaned after 6 weeks of age and slaughtered after 9 weeks of age). Whereas G(T) values remained unaffected by different age and feeding, Isc values were significantly affected by early weaning but were not influenced by age. Irrespective of weaning time active absorption of Na+ tended to be higher by about 60% in 9 weeks old animals. Active absorption of chloride was significantly increased in milk fed 9 weeke old calves and this effect was further stimulated by early weaning. In conclusion, the data show an increasing active Na+ absorption with age in calf rumen that could not be influenced by early weaning. Similarly, active Cl- absorption was initially increased during postnatal development and this effect could be stimulated further by early weaning.

Time structure of behavioral patterns related to feed pecking in chicks

Nonrandom time patterns of pecking acts by 16 chicks were detected using the software Theme during three videotaped pecking sessions (M, C, and A). At 15 days of age pecking session, M (mash) was recorded when chicks ate a mash diet. Pecking session C (change) at 16 or 17 days of age was recorded immediately after the change of the diet to pellets presented either as regular cylinders (P) to eight chicks, or as semiovoid (Po) to eight other chicks. Pecking session A (adapted) was recorded 5 or 6 days after adaptation to P and Po. Successful (consumatory) pecks were 72%, 52%, and 61% of all pecks for sessions M, C, and A, respectively. The head of the chicks remained in a steady position between two consecutive pecks for a longer period during C (65% of the time) than M and A (54%). During C, the pecking rate was less for P (0.54 pecks/s) than for Po (0.79 pecks/s). Two consistent time patterns involving four acts frequently observed were: head rotation (or exploratory peck)-->head in steady position-->consumatory peck-->head in steady position with jaw movements. Time intervals within a pattern were stable throughout sessions. However, the proportion of synchronized (included in a pattern) vs. nonsynchronized (not included in a pattern) acts decreased immediately after the change of feed form (session C). These results suggest that pecking at feed is composed of two distinct sets of acts: consistently organized patterns little affected by the form of the pecked particles and nonsynchronized acts that may be involved in sensory information.

Effect of the H1-histamine receptor agonist betahistine on drinking and eating behavior in pygmy goats

The effect of different doses of the H1-receptor agonist betahistine (0.9 and 2, 4 and 8 mg/kg b.wt.(0.75)) on water and food intake was investigated in 12 pygmy goats. Intraperitoneal (i.p.) injection of betahistine (2, 4, and 8 mg/kg b.wt.(0.75)) stimulated drinking in a dose-dependent manner. Food intake was decreased after the injection of 4 or 8 mg/kg b.wt.(0.75) betahistine, respectively. The increase in water intake was characterized by an increased draft size and decreased latency to drink. The decrease in food intake at the highest dose tested was characterized by an increased latency to eat and by a decreased meal frequency, and food intake associated to drinking was decreased. In line with previous studies, these results support the hypothesis that food-associated drinking is mediated by stimulation of H1-receptors of histamine in pygmy goats.

Effects of histamine H1 receptors on the feeding and drinking patterns in pygmy goats

The goal of these experiments was to determine which histamine receptors are involved in the relationship between drinking and feeding in ruminants. To this end, the effects of the histamine receptor antagonists dexbrompheniramine (H1 receptor antagonist), cimetidine (H2 receptor antagonist), and terfenadine (H1 receptor antagonist) on feeding and drinking patterns of pygmy goats were investigated. Two experiments using dexbrompheniramine [1 and 2 mg/kg of body weight (BW)0.75], two experiments using cimetidine (16 and 32 mg/kg of BW0.75), and two experiments using terfenadine (5 and 11.5 mg/kg of BW0.75) were performed to assess the type and location (periphery or central nervous system) of the histamine receptors involved in the mediation of prandial drinking by pygmy goats. The H1 receptor antagonists dexbrompheniramine (2 mg/kg of BW0.75) and terfenadine (11.5 mg/kg of BW0.75) significantly reduced water intake, but cumulative feed intake did not change. Consequently, the ratio of water intake to feed intake decreased. In contrast, the H2 receptor antagonist did not affect either water or feed intake. Dexbrompheniramine at 2 mg/kg of BW0.75 and terfenadine at 11.5 mg/kg of BW0.75 also decreased draft frequency and decreased the water intake associated with meals. Results showed that blockage of peripheral H1 histamine receptors attenuates the association between water and feed intake in pygmy goats. Therefore, the stimulating effect of feed intake on water intake appears to depend on activation of peripheral H1 histamine receptors.