1,25(OH)2 vitamin D concentration in the plasma of Solanum glaucophyllum intoxicated rabbits

OBJECTIVE: To test Solanum glaucophyllum calcinotic effects in adult New Zealand White rabbits in relation to cumulative dose and active principle concentration in plasma. DESIGN: An intoxication assay with controls. PROCEDURE: Rabbits were orally dosed with aqueous extracts of dry leaves of S glaucophyllum for 5, 7 or 9 days. During the experiment, body weight, calcaemia and phosphataemia were measured; retinal blood vessel calibre was observed by ophthalmoscopic examination of the ocular fundus. 1,25(OH)2 vitamin D plasma concentration was determined at the end of the experimental periods. Soft tissue calcium concentration and the presence of calcinotic lesions were studied after euthanasia. RESULTS: Toxic effects were evident in S glaucophyllum treated groups (loss of body weight, elevation of soft tissue calcium concentration, and presence of calcinotic lesions). Plasma 1,25(OH)2 vitamin D concentrations were negatively correlated with final body weight (r = -0.97; P < or = 0.001), and positively correlated with renal calcium concentration (r = 0.74; P = 0.02). There was also a significant regression of plasma 1,25 (OH)2 vitamin D concentration on the cumulative dose of S glaucophyllum (R2 = 0.87; P < or = 0.001). CONCLUSIONS: The procedure described here offers a sensitive and practical experimental model for the study of the pathogenesis of enteque seco.     

Effect of feeding rumen protected rice bran on calcium homeostasis of non‐lactating multiparous cows

Milk fever in dairy cows can be prevented by activating Ca homeostasis before calving. Homeostatic adaptation can be achieved by reducing dietary Ca availability. Formaldehyde‐treated rice bran was studied to supply rumen protected phytic acid to reduce Ca availability. Twelve multiparous dry cows were used in a 3 × 3 Latin square change‐over design with 5‐day periods to test three dietary treatments. Diets consisted of a forage mix (maize silage, grass silage and hay), being 77% of ration dry matter, supplemented with three concentrates: Control (no formaldehyde‐treated rice bran), T1 (100% formaldehyde‐treated rice bran) and T2 (99.5% formaldehyde‐treated rice bran with 0.6% Ca carbonate, to equal Ca content of Control). Dietary treatments did not affect urine pH (8.14, 8.13 and 8.11 for Control, T1 and T2 respectively) or dry matter intake (13.9, 13.7 and 13.8 kg for Control, T1 and T2 respectively). Including formaldehyde‐treated rice bran in the diet resulted in lower urinary Ca/creatinine ratio (0.970, 0.457 and 0.618 for Control, T1 and T2 respectively). A sudden increase of urinary Ca excretion took place after withdrawal of T1 and T2 at introduction of Control, peaking on the first day and coming back down progressively in the second and third days. Peak was greatest after T1 and was not observed in transitions between rice bran treatments. This is understood as indirect evidence of activation of intestinal Ca absorption during formaldehyde‐treated rice bran feeding, because renal adaptations to changes in blood Ca clearance are immediate and intestinal adaptations delay 2 days. It was concluded that including formaldehyde‐treated rice bran in rations before calving may represent a dietary strategy to prevent milk fever without reducing dry matter intake.     

Fit of Wood's function to weekly records of milk yield, total digestible nutrient intake and body weight changes in early lactation of multiparous Holstein cows in Japan

The aim of this study was to determine the interrelationships between milk yield, total digestible nutrient (TDN) intake and body weight. A total of 14,900 records of weekly (from the 1st week to 20th week after calving) weights of milk yield and TDN intake and body weight from 745 multiparous Holstein cows in Japan were used. In addition, attempts were made to predict energy requirement in early lactation of dairy cows using metabolizable energy (ME) system. The Wood's function (y_t = at^be^− ct) was fitted to each animal record to derive secondary traits (parameters, weeks at peak or bottom, maximum–minimum values and predicted daily body weight gain). The average goodness of fit, as assessed by the R² value, was highest for TDN intake (0.82) and lowest for body weight (0.59). The weeks at peak milk yield and TDN intake and minimum weight were 6.0, 10.0 and 5.5, respectively. Phenotypic correlations within the same trait were negative between parameters a and b and positive between b and c. Relatively large correlations between traits were obtained for a values and maximum–minimum traits (maximum milk yield and TDN intake and minimum body weight). In addition, the phenotypic correlations between predicted daily gain and a value for milk yield were negative during the first 5 weeks after calving. A comparison of ME intakes estimated from Wood's function and ME intake predicted from energy systems showed that the mean-square prediction error (MSPE) was largest in the first week and smallest in the fourth week. The results suggest that the Wood's function is inadequate in predicting body weight changes in early lactation.     

Peripartal calcium homoeostasis of multiparous dairy cows fed rumen‐protected rice bran or a lowered dietary cation/anion balance diet before calving

Milk fever is one of the most important metabolic diseases in dairy cattle. Reducing the dietary cation/anion balance (DCAD) with anionic salts is a common prevention strategy. However, many small European farms cannot use total mixed rations (TMR) in the close‐up period. Including anionic salts in compound feeds can result in feed refusals and moderate inclusions to preserve feed palatability results in insufficient DCAD reduction. Rumen‐protected rice bran induces the adaptation of Ca metabolism in dairy cows by a reduction of Ca intake and by a reduction of the availability of dietary Ca. In the presence of a negative control, rumen‐protected rice bran (2.8 kg/day) was compared with a lowered DCAD diet (from 269 to 4 meq/kg DM) in their effect to prevent milk fever. In a randomized block design, 45 multiparous Holstein cows joined the trial sequentially from 21 days before the expected calving date and were observed until the 8th week of lactation. Feed and nutrient intakes were recorded, and Ca, P, Mg in serum and urine, urine pH, serum NEFA and milk production in early lactation were compared. Feeding rumen‐protected rice bran before calving improved the recovery of calcaemia after calving and had a positive effect on DMI after calving. The moderately low DCAD diet did not positively influence serum Ca at calving. Calcaemia recovered even later than in control, and cows showed reduced DMI post‐calving and higher NEFA levels in the first 36 h after calving. This moderate reduction of DCAD did not provide an intermediate prevention level indicating that DCAD needs to be reduced to the recommended levels to prevent milk fever. Rumen‐protected rice bran may be a suitable feed to reduce hypocalcaemia post‐partum and can be included in pre‐calving compound feeds representing a palatable alternative to anionic salts.     

Urinary calcium excretion in non‐lactating dairy cows in relation to intake of fat‐coated rice bran

At calving, many older cows fail to compensate the sudden demand of calcium by an adequate activation of intestinal absorption. This results in a variable degree of hypocalcaemia. Reducing intestinal availability of calcium during the close‐up period can prevent milk fever. Fat‐coated rice bran (FCRB) was investigated for its potential to reduce Ca availability in pre‐calving cows. Fat‐coated rice bran was incubated in situ to estimate ruminal degradation of dry matter and phytic acid. Also, seven dry multiparous dairy cows were used for a feeding trial in three periods of approximately 1 week each: P1: adaptation; P2: feeding of 2 kg of FCRB and P3: withdrawal of FCRB. Feed intake was recorded and daily urine samples were analysed for pH, Ca and creatinine. The bypass fraction of phytic acid (passage rate: 5%/h) was 30%. Fat‐coated rice bran depressed dry matter intake in P2, resulting in a lower Ca intake. In P2 urine pH and calcium excretion were lower. Daily calcium excretion decreased after introduction of FCRB, peaked after withdrawal and dropped 2 days later. Changes in urinary Ca excretion by feeding FCRB indicate that FCRB affected Ca homeostasis in dry multiparous dairy cows.     

乳牛口服大量β-胡萝卜素对维生素D3及钙磷代谢的影响

６头健康成年荷斯坦乳牛被随机均分为２组。试验组牛第１周每头口服β－胡萝卜素２３．０ｇ,以后每周每头口服１１．５ｇ,对照组不做任何处理。试验期共８周。结果表明,试验组乳牛血清钙及无机磷水平呈下降趋势;血清维生素Ｄ３活性代谢产物２５－ＯＨ－Ｄ３和１,２５－（ＯＨ）２－Ｄ３均呈现明显下降;至第５周末,血液β－胡萝卜素水平最高,２５－ＯＨ－Ｄ３水平下降非常明显。据此认为,乳牛对β－胡萝卜素的吸收存在一阈值,大剂量的β－胡萝卜素进入机体,可能直接干扰维生素Ｄ３的羟化,使其活性代谢产物呈下降趋势,但由于吸收阈值的存在,其对维生素Ｄ３和骨骼钙磷代谢的干扰作用可得到一定程度的减缓。     

Platelet aggregation in dogs after live-virus vaccination

Platelet aggregation induced by ADP was studied in dogs after vaccination with a modified live-virus distemper vaccine. A significant decrease in platelet counts was observed about 1 week after the vaccination. There were no consistent changes in the aggregability of the platelets. In 4 samples the aggregability was significantly increased compared to the prevaccination values. The observed changes will not cause a defective hemostasis in otherwise normal dogs.