Effects of dietary monensin and potassium on apparent absorption of magnesium and other macroelements in sheep

Twelve ruminally cannulated lambs (average weight, 31.1 kg) were used to determine the effects of monensin and K on apparent absorption of Mg in lambs. Lambs were assigned randomly to two groups and fed a basal high concentrate diet containing .44% K with or without 20 mg/kg monensin for 19 d of dietary adjustment. During adjustment, lambs were housed by treatment group and given ad libitum access to their diets. Following dietary adjustment, lambs were placed in individual metabolism stalls and fed 450 g of their respective diet twice daily. Within each monensin group, lambs were infused ruminally with 0, 7.6 or 31.6 g K/d (equal amounts at each feeding in 158 ml of distilled-deionized water) during three periods in a 3 X 3 Latin-square arrangement of K treatments. Each period consisted of a 10-d preliminary phase and a 7-d collection phase followed by a 3-d D2O infusion phase to determine water turnover. Addition of monensin to the diet decreased (P less than .05) fecal Mg excretion 15.9%. Apparent absorption and retention of Mg were increased (P less than .05) with the addition of monensin. Increasing K level increased (P less than .05) fecal Mg excretion. Apparent absorption of Mg decreased (P less than .05) from .93 to .80 g/d when either level of K was infused into the rumen. Monensin decreased the acetate:propionate (A:P) ratio. There was a significant interaction between monensin and K level for acetate and propionate (molar %), and A:P ratio. In the presence of higher K concentrations, monensin appears to be more effective in decreasing the A:P ratio.(ABSTRACT TRUNCATED AT 250 WORDS)     

Site of magnesium and other macromineral absorption in steers fed high levels of potassium

Six Angus x Simmental steers, surgically equipped with abomasal and ileal cannulae, were used during three metabolism trials. Steers were blocked according to weight ad were allotted to three dietary K levels (.6, 2.4 and 4.8% dry basis) for each trial with the restriction that no animal would receive the same level during two successive trials. Each trial consisted of a 5-d transition, a 10-d preliminary period, a 7-d collection of feed, feces and urine and a 6-d sampling of feed, feces and abomasal and ileal fluid. Chromic oxide (.5%) was used as an indicator to measure flow through the digestive tract. Magnesium absorption decreased linearly (P less than .05) with increasing level of dietary K. The primary site of Mg absorption was the preintestinal region followed by a net secretion into the small intestine. Preintestinal Mg absorption was decreased 39% when 4.8% K was fed. Serum Mg was lower at high levels of dietary K. Potassium absorption increased linearly when expressed as g/d and curvilinearly when expressed as percentage of intake, with increasing levels of dietary K. When .6% K was fed, the primary site of K absorption was the small intestine, but with the high levels of K, the preintestinal region was also an important site of absorption. The effect of high K level on Mg absorption in steers was similar to that observed previously in sheep.     

Effect of dietary phosphorus and roughage levels on calcium, magnesium and potassium utilization by sheep

Three levels of dietary P (.12%, .24% and .48% of dry matter) and three levels of roughage as ground corn cobs (25% 50% and 75% of dry matter) were fed in a 3 X 3 factorial metabolism trial, utilizing 36 crossbred (Hampshire X Columbia) intact male lambs, 6 to 9 mo of age. All diets contained cane molasses (5%), blood meal (13.5%), urea (1%), corn oil (1%) and salt (.5%). Limestone supplied supplemental Ca and treatment P levels were supplied by monosodium phosphate. Equal levels of corn starch and cerelose supplied the remainder of the diet. The diet was fed ad libitum, once daily. The highest P level (.48% P) resulted in a negative (P less than .01) Ca balance (-.23 g/d vs .12 g/d for .12% P and .31 g/d for .24% P groups), and apparent digestibility (P less than .01) of Ca (1.65% vs 17.18 and 22.2% for the two respective lower P dietary levels). Blood serum concentrations of Ca and Mg decreased (P less than .01) as dietary P level was increased. Apparent digestibility of Mg was decreased (P less than .05) by the highest P level (6.9% vs 21.58% and 18.80% for the two lower levels of dietary P). Level of roughage had no effect on Ca and Mg utilization; however, the highest level (75% corn cobs) resulted in improved (P less than .05) K balance (.85 g/d vs .30 and .50 g/d for the two lower levels of roughage).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary potassium and sodium on magnesium utilization in sheep

Two metabolism trials were conducted to determine the effect of altering dietary Na and K on Mg availability. Three dietary treatments (normal K-normal Na, high K-normal Na and high K-high Na) were imposed upon nine crossbred wether lambs in a randomized block design. Each trial consisted of a 5-d diet adjustment, a 10-d preliminary period and a 5-d collection of feed, feces and urine. Increasing K and Na intake increased the percentage of Mg excreted in feces. Both elevated K and K-Na depressed (P less than .10) urinary Mg excretion, primarily a reflection of depressed Mg absorption in animals fed these diets. Apparent K absorption and retention increased when animals were supplemented with K. Addition of Na to the diet did not alter absorption or retention of K. Apparent K and Na availability increased when K and Na supplements were included in the diet. This increased availability resulted from increased total absorbed K and Na compared with a fixed endogenous excretion. Calcium balance in lambs was not affected by addition of K or Na. Lambs were able to absorb enough Mg from their respective diet to maintain normal serum Mg levels. Addition of Na to a diet high in K did not enhance Mg absorption in lambs.     

Effects of potassium on macromineral absorption in sheep fed wheat straw-based diets

Two experiments were conducted to determine the effect of increasing dietary K on macromineral bioavailability from a wheat straw-hay diet, and to monitor changes in the rumen that could affect mineral availability. In the first experiment, 12 mature wethers were used in a metabolism study to determine the effect of adding potassium chloride (KCl) to a supplement fed with a diet of 55% NH3-treated wheat straw and 45% bromegrass hay. In the second experiment, similar diets were fed to six wethers with ruminal and abomasal cannulae to determine the site of mineral absorption. Dietary K levels were 1, 2 and 3% of the diet dry matter. Increasing K tended to decrease (P less than .06) apparent absorption of Mg. Potassium absorption increased (P less than .01) with increasing dietary K, but retention was not altered. Quadratic effects (P less than .01) of K were observed for Ca and P apparent absorption and retention. Increased K lowered (P less than .05) plasma Mg in Exp. 1 but not in Exp. 2. Ruminal concentrations of K increased (P less than .01), and concentrations of Na decreased (P less than .05), as dietary K increased. Ruminal fermentation was influenced by dietary K level. Molar proportions of acetate in the rumen were increased (P less than .01) by the addition of K to the diet, while molar proportions of butyrate (P less than .01) and valerate (P less than .01) decreased linearly with increasing K. Time X treatment interactions were present for ruminal propionate, butyrate and NH3-N (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

体外产气法研究不同钾水平日粮对绵羊瘤胃发酵的影响

<正>近年来通过调控瘤胃发酵来提高反刍动物饲料转化率及生产性能一直是反刍动物营养研究的重点之一。钾对瘤胃微生物的生长以及瘤胃发酵都是必需的,不同钾水平的日粮在很大程度上影响了瘤胃发酵模式及动物的生产性能。20世纪90年代初以来,体外产气法由于能够较好地模拟瘤胃中的发酵历程和     

Absorption of magnesium and other macrominerals in sheep infused with potassium in different parts of the digestive tract

Two metabolism trials were conducted with 12 crossbred wether lambs, each surgically equipped with a ruminal catheter and abomasal and ileal cannulae, to study the effect of K infusion in different sites of the digestive tract on site of absorption and flow of minerals. The treatments consisted of the infusion of 33.6, 12.0 or 12.0 g K/d as bicarbonate into either the rumen, abomasum or ileum, respectively. Each trial consisted of a minimum 5-d preliminary period, five 3-d collection periods to determine mineral balance and a 6-d sampling period to determine mineral flow and site of absorption. Chromic oxide was incorporated into the diet for use as a marker. Magnesium was absorbed primarily from the preintestinal region. Ruminal infusion of K tended to decrease preintestinal Mg absorption. Absorption of Mg in the entire tract was decreased (P less than .05) 43% when K was infused into the rumen. There was a slight absorption of Mg in the small intestine, followed by a net secretion into the large intestine. Serum Mg levels tended to be depressed in lambs infused with K intraruminally. Calcium flow from the preintestinal region was decreased (P less than .05) by infusion of K into the rumen. Only lambs infused with K in the rumen had a net secretion of Na into the small intestine. The large intestine was the primary site of net Na absorption for ruminal-infused lambs. Phosphorus flow from the preintestinal region was decreased (P less than .05) by infusion of K into the rumen. Potassium flow from both the preintestine and small intestine was increased (P less than .05) by ruminal K infusion. The infusion of K into the rumen, abomasum or ileum increased (P less than .05) the total absorption of K, with the small intestine being the major absorptive site. The infusion of potassium bicarbonate into the rumen of sheep raised (P less than .05) the pH of the ruminal contents 15%. Ruminal infusion of K depresses Mg absorption, while the infusion of K into the abomasum or ileum does not affect Mg absorption. Therefore, the role of K in grass tetany may be via this depression of Mg absorption.     

Site and extent of apparent magnesium absorption by lambs fed different sources of magnesium

Ten abomasally cannulated crossbred wether lambs (avg wt, 33 kg) were used in a replicated 5 x 5 latin square design to determine the site and extent of apparent absorption of Mg when fed different sources of Mg. Lambs were fed twice daily 220 g of chopped mixed grass hay and 180 g of a corn-based supplement (control; .13% mg, DM basis), or the control diet supplemented with Mg (.26% Mg, DM basis) from MgO, magnesium citrate (MgC), smectite-vermiculite (Mg-Mica) or MgOH. Lambs were maintained in metabolism stalls during each of the five experimental periods. Each period consisted of a 7-d dietary adjustment followed by a 3-d collection of abomasal samples, feces and urine. Abomasal contents were sampled four times daily during the 3-d collection period. The diet contained .5% chromium oxide as a digestion marker. Apparent absorption of Mg was .17, .55, .85, .78 and .82 g/d for lambs fed the control, MgO, MgC, Mg-Mica and MgOH diets, respectively. Apparent absorption of Mg (g/d) was similar (P greater than .05) in the lambs fed the supplemented diets and greater (P less than .05) than in those fed the control diet. Preintestinal absorption of Mg was .21, .57, 1.08, .14 and .92 g/d when the control, MgO, MgC, Mg-Mica and MgOH diets were fed. Lambs fed the control and Mg-Mica diets absorbed similar (P greater than .05) quantities of Mg in the preintestinal region and less (P less than .05) than lambs fed the MgO, MgC and MgOH diets.(ABSTRACT TRUNCATED AT 250 WORDS)     

纤维素复合酶不同添加量对舍饲绵羊增重的影响

以纤维素酶为主的复合酶在反刍动物中的应用越来越广泛 ,但由于酶制剂的费用较高限制了其应用。为进一步掌握最佳添加量 ,我们在以往试验的基础上 ,对纤维素复合酶不同添加量对舍饲绵羊的增重效果进行了试验研究。1　材料和方法1 1　纤维素复合酶　主要成分为纤维素酶、木聚糖     

日粮硝酸钾添加量对湖羊瘤胃细菌群落结构的影响

试验旨在研究湖羊采食高剂量硝酸钾日粮的瘤胃细菌群落结构的变化规律。采用高通量测序和RT-PCR方法,以不添加硝酸钾为对照,研究了日粮添加6、12、18、24 g/d和30 g/d硝酸钾的瘤胃细菌多样性、群落结构和硝酸盐还原菌相对丰度。结果表明,30 g/d以内的硝酸钾剂量不影响瘤胃细菌群落的丰度和多样性。拟杆菌门、厚壁菌门和变形菌门是优势菌群,12 g/d和18 g/d的日粮硝酸钾显著增加了拟杆菌门和普雷沃氏菌属的相对丰度(P<0.05),但随着硝酸钾剂量的升高,细菌相对丰度下降。日粮添加30 g/d以内硝酸钾不影响反刍兽新月单胞菌的相对丰度,但显著升高胎儿弯曲杆菌的相对丰度(P<0.05)。湖羊瘤胃细菌群落结构与日粮硝酸钾含量相关。     

Utilization of magnesium and other macrominerals in sheep supplemented with different readily-fermentable carbohydrates

Sheep were used to determine the effects of dietary supplementation with readily-fermentable carbohydrates on Mg, Ca, K and P utilization. In each of two metabolism trials, 15 mature, crossbred wethers (average weight, 49.2 kg) were allotted to five dietary treatments consisting of 800 g/d of orchardgrass (Dactylis glomerata, L.) hay alone, or supplemented with 450 g/d of either glucose, sucrose, lactose or starch. Each trial consisted of a 5-d adjustment period, a 10-d preliminary period and a 10-d collection period. Compared with wethers fed hay alone, supplementation with each kind of carbohydrate to the diet decreased (P less than .05) fecal Mg excretion and increased (P less than .05) apparent absorption and retention of Mg. Apparent absorption of the Ca was lower (P less than .05) in wethers fed lactose and tended to be decreased by glucose, sucrose and starch supplementation. Calcium retention was lower (P less than .05) in wethers fed sucrose and lactose, compared with those fed hay alone. All types of supplementary carbohydrates depressed (P less than .05) apparent absorption and urinary excretion of K. Serum Mg and Ca were not affected and serum K was depressed (P less than .05) by carbohydrate supplementation. Ruminal fluid pH was decreased (P less than .05) by glucose and lactose supplementation, and addition of these carbohydrates tended to decrease molar proportions of acetate and increase those of propionate and butyrate, compared with sheep fed hay alone. Sucrose addition decreased (P less than .05) acetate and increased (P less than .05) butyrate molar proportions in the ruminal fluid.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of L-carnitine supplementation on utilisation of energy and protein in broiler chicken fed different dietary fat levels.

Effects of a supplementation of 80 mg L-carnitine per kg diet were studied in broiler chicken at two dietary levels of fat (4 and 8%) and different feeding levels (ad libitum in a growth trial, 95 and 85% of ad libitum in a balance trial). A low-carnitine basal diet adequate in amino acid concentration was used. In the growth trial, each diet was fed to 9 groups of 10 birds each for 16 days from day 5 of live onwards. Growth and feed intake were determined. At the end of the trial, birds were killed and homogenised for subsequent empty body analysis. Accretion of protein and energy was determined using a representative blank group killed at the beginning of the trial. In the balance trial, 8 individual birds were used per treatment. Birds were offered the feed at approximately 85 and 95% of ad libitum intake, which was determined with separate birds for both fat levels. Excreta were quantitatively collected three times daily for 8 consecutive days beginning on day 17 individually for each bird. Supplemented L-carnitine did not significantly affect any response criterion. However, growth and feed conversion tended to be improved by about 5% in the carnitine supplemented diets when fed ad libitum. An interaction between carnitine and fat level occurred with regard to feed conversion, indicating that carnitine had a positive effect at the high fat level, but not at the low fat level. L-carnitine did not positively affect the metabolisability of energy (ME/GE) and the efficiency of energy utilisation (RE/GE or RE/ME). Similarly, no significant carnitine effect was determined with regard to N accretion and the efficiency of utilisation of dietary protein in both trials. It is concluded that endogenous carnitine synthesis is not the limiting factor for energy utilisation in broiler chicken, even at high dietary fat concentration. Occasionally reported positive effects of supplemental carnitine were likewise caused by reasons other than improved energy or protein utilisation. Further studies on amino acid utilisation and catabolism should consider marginal amino acid supply.     

Macromineral absorption in sheep fed tetany-prone and non-tetany-prone hays

Two experiments were conducted to determine some of the factors that led to hypomagnesemic tetany associated with the feeding of two orchardgrass hays. Sixteen mature Columbia and Suffolk wethers (62 to 72 kg), four of which were fitted with ruminal and abomasal cannulae, were fed one of two tetany-prone orchardgrass hays or a non-tetany-prone bromegrass hay. In Exp. 1, 12 wethers were used in a completely random design metabolism experiment to measure apparent absorption and retention of macrominerals. In Exp. 2, four wethers with ruminal and abomasal cannulae were used in a completely random design experiment to monitor pre-intestinal mineral absorption and ruminal characteristics. This experiment was replicated once, with wethers remaining on their diets for 16 d in each replication. In the metabolism experiment, apparent absorption and retention of Mg as a percentage of intake were lower (P less than .01 and P less than .05) for one tetany-prone orchardgrass hay compared with the other orchardgrass hay. Pre-intestinal absorption of Mg in the cannulated wethers was greater (P less than .01) for the orchardgrass hays than for the bromegrass hay. Pre-intestinal Mg absorption was higher (P less than .01), both in terms of grams per day and a percentage of intake for the orchardgrass hay with the highest Mg content. In the noncannulated wethers, the percentage of water-soluble Mg in the feces was lower (P less than .01) for the tetany-prone hays, indicating that a decrease in Mg solubility in the intestine may have influenced Mg apparent absorption.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of supplemented magnesium from magnesium oxide or dolomitic limestone upon digestion and absorption of minerals in sheep

Three metabolism trials were conducted with six lambs fitted with abomasal and ileal cannulae to determine the site of supplemental Mg absorption when supplied as dolomitic limestone or magnesium oxide. Magnesium intake was 1.09 g/d for the lambs fed the control diet and 2.21 and 2.10 g for those fed the dolomitic limestone and magnesium oxide supplemented diets, respectively. Irrespective of its source, the major site of Mg absorption was the preintestinal region. Magnesium was secreted in the small intestine in lambs fed all three diets. Magnesium supplementation resulted in an increase (P less than .05) in preintestinal Mg absorption, with magnesium oxide having the highest value. Supplementation had no effect (P greater than .05) on secretion or absorption of Mg from the small and large intestines or total retention of Mg. With all three diets, the major site of Ca absorption was the stomach region with additional absorption taking place in the large intestine. Calcium was secreted in the small intestine of lambs fed all treatments. Generally, K, Na and P were secreted in the preintestinal region and absorbed from the small and large intestines. The major site of K and P absorption appeared to be the small intestine and for Na, the large intestine. Serum minerals were unchanged (P greater than .05) due to treatment, but the levels of Mg, K and inorganic P tended to be higher in lambs supplemented with either of the Mg sources. It appears that the greater utilization of Mg from magnesium oxide vs dolomitic limestone is due to greater absorption of Mg from the forestomach region.     

Effect of feed intake and dietary vitamin A levels on sheep performance.

A study was conducted on 20 "Rahmani" male lambs of 16 kg body weight fed on normal feed level and high vitamin A level (NF-HV); normal feed level and normal vitamin A level (NF-NV); low feed level and high vitamin A level (LF-HV) or low feed level and normal vitamin A level (LF-NV) till slaughter weight of 35-40 kg. Average daily gains of lambs were 211, 148, 117 and 87 g for the NF-HV, NF-NV, LF-HV and LF-NV groups, respectively. The corresponding feed conversions were 4.3, 5.9, 5.0 and 6.4 kg DM/kg gain. Raising feed intake and vitamin A level enhanced nutrients digestibility and nitrogen balance. Rumen liquor reflected higher pH value in animals fed higher intake (NF) in the first two diets. Both feed intake and vitamin A levels enhanced volatile fatty acids and ammonia concentrations in the rumen liquor. Feed intake and vitamin A levels positively affected haemoglobin content, packed cell volume, glucose, urea, total protein, vitamin A, insulin, cholesterol, phospholipids, glutamate oxaloacetate and glutamate pyruvate transaminases and alkaline phosphatase in blood Vitamin A, insulin, cholesterol and phospholipids in blood increased gradually over the experimental period. Dressing percentages were 56.2, 49.6, 49.1 and 44.6% for the experimental groups, respectively. Liver content of glycogen and vitamin A increased with increasing feed intake and vitamin A levels. It is concluded that higher levels of vitamin A supplementation (than usually recommended) is required during fattening of lambs. Low energy and normal vitamin A levels are not recommended in lambs feeding.