l-carnitine supplementation and lipid metabolism of rats fed a hyperlipidaemic diet

Until now, there has been no clear knowledge about the effect of dietary carnitine supplementation on lipid metabolism. Therefore, this study was conducted to investigate the effect of a dietary l -carnitine supplementation (500 mg/kg) onx the lipid metabolism of adult rats. Rats fed a hyperlipidaemic basal diet containing 15% lard and 1% cholesterol were used as an animal model. The feeding period was 6 weeks. As parameters of lipid metabolism, the concentrations of individual lipids in plasma, lipoproteins and liver and the fatty acid composition of liver and erythrocyte total lipids were determined. There were no significant differences between the control group and the group receiving the diet supplemented with carnitine on parameters of animal performance (daily body weight gains and feed conversion ratio). As expected, plasma, very low-density lipoproteins (VLDL) and liver exhibited high concentrations of cholesterol. Concentrations of triglycerides and phospholipids in plasma and individual lipoproteins as well as the concentrations of triglycerides, cholesterol and phospholipids in the liver were not significantly altered by dietary carnitine supplementation. The concentration of cholesterol in plasma and liver was increased by dietary carnitine. The fatty acid composition of liver and erythrocyte total lipids was not influenced by dietary carnitine supplementation. In conclusion, this study does not indicate a lipid-lowering effect of dietary carnitine supplementation in hyperlipidaemic rats. Probably, the essential functions of carnitine in metabolism were realized by carnitine which was synthesized endogenously.     

Relationship between size of the ovulatory follicle and pregnancy success in beef heifers

Previous research indicated that the size of the ovulatory follicle at the time of insemination significantly influenced pregnancy rates and embryonic/fetal mortality after fixed-timed AI in postpartum cows, but no effect on pregnancy rates was detected when cows ovulated spontaneously. Our objective was to evaluate relationships of fertility and embryonic/fetal mortality with preovulatory follicle size and circulating concentrations of estradiol after induced or spontaneous ovulation in beef heifers. Heifers were inseminated in 1 of 2 breeding groups: (1) timed insemination after an estrous synchronization and induced ovulation protocol (TAI n = 98); or (2) AI approximately 12 h after detection in standing estrus by electronic mount detectors during a 23-d breeding season (spontaneous ovulation; n = 110). Ovulatory follicle size at time of AI and pregnancy status 27, 41, 55, and 68 d after timed AI (d 0) were determined by transrectal ultrasonography. Only 6 heifers experienced late embryonic or early fetal mortality. Interactions between breeding groups and follicle size did not affect pregnancy rate (P = 0.13). Pooled across breeding groups, logistic regression of pregnancy rate on follicle size was curvilinear (P < 0.01) and indicated a predicted maximum pregnancy rate of 68.0 +/- 4.9% at a follicle size of 12.8 mm. Ovulation of follicles < 10.7 mm or > 15.7 mm was less likely (P < 0.05) to support pregnancy than follicles that were 12.8 mm. Ovulatory follicles < 10.7 mm were more prevalent (28% of heifers) than ovulatory follicles > 15.7 mm (4%). Heifers exhibiting standing estrus within 24 h of timed AI had greater (P < 0.01) follicle diameter (12.2 +/- 0.2 mm vs. 11.1 +/- 0.3 mm) and concentrations of estradiol (9.9 +/- 0.6 vs. 6.6 +/- 0.7) and pregnancy rates (63% vs. 20%) than contemporaries that did not exhibit behavioral estrus. However, when differences in ovulatory follicle size were accounted for, pregnancy rates were independent of expression of behavioral estrus or circulating concentration of estradiol. Therefore, the effects of serum concentrations of estradiol and behavioral estrus on pregnancy rate appear to be mediated through ovulatory follicle size, and management practices that optimize ovulatory follicle size may improve fertility.     

Metabolic functions of L-carnitine and its effects as feed additive in horses. A review.

L-carnitine, a betaine derivative of beta-hydroxybutyrate, is found in virtually all cells of higher animals and also in some microorganisms and plants. In animals it is synthesized almost exclusively in the liver. Two essential amino acids, i.e., lysine and methionine serve as primary substrates for its biosynthesis. Also required for its synthesis are sufficient amounts of vitamin B6, nicotinic acids, vitamin C and folate. The first discovered ergogenic function of L-carnitine is the transfer of activated long-chain fatty acids across the inner mitochondrial membrane into the mitochondrial matrix. For this transfer acyl-CoA esters are transesterified to form acylcarnitine esters. Thus, in carnitine deficiency fat oxidation and energy production from fatty acids are markedly impaired. Skeletal muscles constitute the main reservoir of carnitine in the body and have a carnitine concentration at least 200 times higher than blood plasma. Uptake of carnitine by skeletal muscles takes place by an active transport mechanism which transports L-carnitine into muscles probably in the form of an exchange process with gamma-butyrobetain. In young animals including foals, the capacity for biosynthesis of carnitine is not yet fully developed and apparently cannot meet the requirements of sucking animals. Sucking animals depend therefore on an extra supply of carnitine which is usually provided with milk. Additionally, young animals including foals possess a lower concentration of carnitine in blood plasma than adult animals. Besides its role as carrier of activated acyl groups, L-carnitine functions as a buffer for acetyl groups which may be present in excess in different tissues during ketosis and hypoxic muscular activity. Other functions of L-carnitine are protection of membrane structures, stabilizing of a physiologic CoA-SH/acetyl-CoA ratio and reduction of lactate production. Animal's derived feeds are rich in L-carnitine whereas plants contain usually very little or no carnitine. Carnitine is absorbed from the small intestine by active and passive transport mechanisms. From the increase in renal excretion of L-carnitine after oral supplementations of 10 g/d to horses it has been concluded that the efficiency of absorption of L-carnitine is rather low (about 5 to 10% of the supplied dose). A further decrease in fractional carnitine absorption was observed when the oral dose of carnitine was increased. L-carnitine is virtually not degraded in the body and renal excretion of carnitine is comparatively small under normal conditions. The concentration of L-carnitine in blood plasma of horses varies markedly between animals and between different days. In addition, circadian changes in carnitine concentration in plasma have been reported. Peak concentrations were found during late afternoon, being up to 30% higher than those in the morning. In breeding mares the carnitine concentration in blood plasma declines with onset of lactation. In resting skeletal muscles about 90% of the total carnitine content is present as free carnitine with the remaining part being available as carnitine esters. With increasing exercise intensity a continuing greater proportion of free carnitine (up to 80%) is converted into carnitine esters, mainly into acetylcarnitine. This shift from free to acetylcarnitine is readily reversed within about 30 min after termination of exercise. It appears that acute exercise does not have a marked effect on the content of total carnitine in skeletal muscle whereas training seems to elevate its total concentration in the middle gluteal muscle of 3 to 6 year old horses and to reduce variation of its concentration compared to age-matched untrained horses. Oral supplementations of 5 to 50 g of L-carnitine per day to horses elevated the carnitine concentration in blood plasma to about twice its basal concentration. No clear relationship existed, however, between the orally administered dose of carnitine and the increase of L-carni     

Certain physiochemical properties of uterine tubal fluid, follicular fluid, and blood plasma in the mare.

Uterine tubal fluids were collected twice a day from mares for 5 consecutive estrous cycles between March 15 and September 1. Follicular fluids were aspirated from the follicles of exteriorized ovaries of 3 mares between days 2 and 5 of estrus. Uterine tubal fluid and follicular fluid were analyzed for osmolarity, dry matter, total lipids, total free fatty acids, glucose, fructose, and lactic acid. Blood samples were collected (jugular venipuncture) throughout the estrous cycle, and the same physical and biochemical analyses were made on blood plasma. A difference (P less than 0.01) was found for osmolarity between uterine tubal fluids collected during estrus and those collected during anestrus. The osmolarity of uterine tubal fluid during anestrus was greater than that of blood plasma; follicular fluid was similar in osmolarity to blood plasma. The dry matter in blood plasma was greater (P less than 0.01) than that in either uterine tubal fluid or follicular fluid. Cyclic variations in dry matter content were not observed in uterine tubal fluid. Total lipids in blood plasma and follicular were greater (P less than 0.01) than those in uterine tubal bluid. The concentration of total lipid in uterine tubal fluid was similar during estrus and anestrus. Myristic acid (C14:0) in blood plasma and myristoleic acid (C14:1) in uterine tubal fluid were the only free fatty acids that had cyclic variation. The fatty acids in the greatest concentration in uterine tubal fluid and blood plasma were palmitic acid (C16:0) and linoleic acid (C18:2). Concentrations of linoleic acid and stearic acid (C18:0) were greater (P less 0.01) in follicular fluid than in uterine tubal fluid or blood plasma. Only trace amounts of glucose were detected in uterine tubal fluid, whereas a considerable amount of glucose was found in follicular fluid. Fructose was not detected in any of the fluids. Lactic acid concentrations did not differ between estrus and anestrus. Lactic acid concentration was significantly greater (P less than 0.01) in uterine tubal fluids and follicular fluids than in blood plasma.     

Endocrine changes and ultrasonography of ovaries in suckled beef cows during resumption of postpartum estrous cycles

Changes in follicular and luteal structures were assessed and concentrations of estradiol and progesterone were measured in 13 Hereford X Angus suckled beef cows during resumption of estrous cycles. Transrectal ultrasonography was used to monitor follicular size, ovulation, and formation and regression of the corpus luteum (CL). The interval from parturition to first postpartum ovulation (FO) was 82 +/- 4.7 d. Serum progesterone remained low before FO. One cow exhibited standing estrus, two cows showed other signs of estrus, and 10 displayed no signs of behavioral estrus preceding FO. All cows exhibited standing estrus before the second postpartum ovulation (SO). All cows had a short luteal phase after FO, with an average interval of 8.5 +/- .2 d between FO and SO. Concentrations of estradiol in serum during the 8 d preceding ovulation were similar before FO and SO. Maximal diameter of the preovulatory follicle was similar before FO and SO. However, the ovulatory follicle was larger in diameter at 2 d (P = .02) and 3 to 8 d (P less than .005) before FO than before SO. The time from detection until ovulation was less (P = .005) for the ovulatory follicle preceding SO than for the follicle associated with FO (8.5 vs 10.2 d, respectively, SE = .4). The second-largest follicle was larger (P less than .005) in diameter during the 8 d preceding the FO than before the SO. The difference in size between the ovulatory follicle and the second-largest follicle on the day before ovulation was greater (P less than .005) preceding SO than preceding FO (8.7 vs 6.6 mm, respectively, SE = .4).(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma, tissue, and urine carnitine concentrations in healthy adult cats and kittens

Mean carnitine concentrations [( carnitine]) were higher (P less than 0.05) in adult cats than in kittens for skeletal muscle (total and free carnitine), myocardium (free carnitine), and urine (total and free carnitine). The free/total carnitine ratio was lower (P less than 0.05) in kittens than in adults for liver, myocardium, and urine. Carnitine concentrations were similar between genders in kittens, but in adult cats, [carnitine] in plasma (total, free, and esterified carnitine) and liver (total and free carnitine) were higher (P less than 0.05) in female than in male cats. Total and free plasma [carnitine] were correlated to total and free liver [carnitine], respectively. Skeletal muscle [carnitine] was not correlated to plasma [carnitine]. Correlations in [carnitine] between plasma and myocardium, kidney, or urine were inconsistent.     

湖羊不同发育阶段卵泡内代谢产物和激素含量的比较研究

本试验旨在研究代谢产物、代谢激素和生殖激素在湖羊黄体期不同发育卵泡内的变化。选用体质量40kg左右的湖羊11头,同期发情结束后第12天屠宰,按不同大小卵泡分离卵泡液。试验结果表明,与≤2.5mm卵泡相比,>2.5mm卵泡内的葡萄糖浓度显著提高(P<0.05),胰高血糖素浓度显著降低(P<0.05),乳酸脱氢酶(LDH)活性和睾酮浓度极显著降低(P<0.01),雌二醇浓度极显著提高(P<0.01),而血氨、游离脂肪酸、尿素、胰岛素和孕酮浓度差异不显著。雌二醇浓度与LDH活性呈极显著负相关(P<0.01),与葡萄糖浓度呈显著正相关(P<0.05),与胰高血糖素浓度呈显著负相关(P<0.05),与睾酮浓度呈极显著负相关(P<0.01),与孕酮浓度接近正相关(P=0.051)。试验结果表明代谢产物和激素共同参与调节卵泡发育。     

Hormonal response to dobutamine cardiac stress testing in a conscious canine model of early left ventricular dysfunction induced by chronic rate overload

The aims of this study were to investigate (1) hormonal activation before and during dobutamine cardiac stress testing (DST) in a canine model of early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP) and (2) the relationship between this hormonal profile and carnitine concentrations.Before the pacing period, the 6 dogs were assigned to 2 groups according their baseline total plasma carnitine concentration. A DST was performed on each dog before activation of the pacemaker and every 3 to 4 days during development of 3 progressive stages of ELVD (stages 1, 2 and 3). Plasma atrial natriuretic factor (ANF), angiotensin II (ANG II) and endothelin-1 (ET-1) levels were measured at the start and at the end of each DST. Effects of ELVD, DST and plasma carnitine concentration on these measurements were tested.The RRVP induced a significant increase of ANF and ANG II and a non significant trend toward increase of ET-1 in all dogs.Before the pacing period, ANF remained constant during the DST in dogs with normal total plasma carnitine concentration, while it significantly decreased in dogs with low total plasma carnitine concentration. Dobutamine stress testing induced a significant decrease in ANF in all dogs in ELVD. Dobutamine infusion induced a significant increase in ANG II in all dogs before as well as during the pacing period while ET-1 was unchanged.These results suggest that investigation of the hormonal profile before and after a dobutamine challenge might provide important diagnostic information in dogs with asymptomatic or mildly symptomatic cardiac dysfunction of different origins.     

Follicular dynamics and steroid profiles in cows during and after treatment with progestin-based protocols for synchronization of estrus

Two progestin-based protocols for the synchronization of estrus in beef cows were compared. Cyclic, nonlactating, crossbred, beef cows were assigned by age and body condition score to one of two treatments. Cows assigned to the MGA Select protocol were fed melengestrol acetate (MGA; 0.5 mg x cow(-1) x (-1)) for 14 d, GnRH was administered (100 microg i.m. of Cystorelin) 12 d after MGA withdrawal, and PGF2alpha (25 mg of i.m. Lutalyse) was administered 7 d after GnRH. Cows assigned to the 7-11 Synch protocol were fed MGA for 7 d and were injected with PG on d 7 of MGA, GnRH on d 11, and PG on d 18. Transrectal ultrasonography was performed daily to monitor follicular dynamics from the beginning of MGA feeding through ovulation after the synchronized estrus. All cows exhibited estrus in response to PG. Mean interval to estrus was shorter (P < 0.01) for 7-11 Synch-treated cows (56 +/- 1.5 h) than for cows assigned to the MGA Select protocol (73 +/- 4.7 h). Mean interval from estrus to ovulation did not differ between treatments (P > 0.10). Variances for interval to estrus differed (P < 0.01) between treatments. Mean follicular diameter at GnRH injection, PG injection, and estrus did not differ (P > 0.10) between treatments. Relative to MGA Select, serum estradiol-17beta concentrations were higher (P < 0.01) for 7-11 Synch 2 d and 1 d before, on the day of GnRH injection, in addition to 4 d after GnRH, and 24 h after PG. Mean progesterone concentrations were greater (P < 0.01) for MGA Select cows from 4 d before to 7 d after GnRH. Forty-four percent of the variation in interval to estrus between treatments was explained by differences in estradiol-17beta concentrations 24 h after PG. This study suggests that follicular competence is likely related to steroidogenic capacity of the follicle and the endocrine environment under which growth and subsequent ovulation of the dominant follicle occurs.     

Effects of fish oil and conjugated linoleic acids on carnitine homeostasis in laying hens

1. The effects of n?3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acids (CLA) on genes involved in carnitine homeostasis were compared in laying hens. Three groups of laying hens were fed on a control diet or a diet with either 3% of fish oil or CLA for 4 weeks.

2. Feed intake and egg production rate did not differ between the three groups. Diets with fish oil or CLA had only a weak effect on mRNA levels of PPARα target genes (ACO, CPT-I) in the liver and did not influence mRNA concentrations of the most important carnitine transporter OCTN2, enzymes of involved in carnitine synthesis (TMLD, TMABA-DH, BBD) or concentrations of carnitine in plasma, liver and total egg contents.

3. Hens fed the CLA diet had lower concentrations of free and total carnitine in egg yolk but higher concentrations of carnitine in albumen than control hens (P? 4. In conclusion, the study showed that feeding fish oil or CLA causes only a weak activation of PPARα in tissues of laying hens that probably explained the lack of effect on carnitine homeostasis. The results contrast with those in humans and mice that show a significant effect of synthetic PPARα agonists on carnitine homeostasis in humans and mice.     

Testosterone administration to mares during estrus: duration of estrus and diestrus and concentrations of LH and FSH in plasma

To study the possible role of ovarian androgens in regulation of follicle stimulating hormone (FSH) secretion in the cycling mare, five mature, intact mares were treated with testosterone (20 micrograms/kg of body weight) daily during estrus; five control mares received safflower oil on the same schedule. Mares were teased for estrus and samples of jugular blood were drawn daily through one full estrous cycle. Concentrations of FSH in plasma were measured by a newly developed radioimmunoassay based on anti-ovine FSH serum and radioiodinated equine FSH. Testosterone treatment during estrus had no effect on duration of estrus, diestrus or the total cycle. Concentrations of FSH in plasma during estrus were unaffected by testosterone treatment. However, FSH concentrations in testosterone-treated mares were elevated (P less than .05) compared with controls during mid-diestrus (d 6 through 11). The magnitude and timing of the LH peaks were unaffected by treatment, as was the day on which the first elevated progesterone concentration occurred. These data are consistent with a model of FSH secretion in which ovarian androgens cause an accumulation of FSH in the pituitary during estrus in preparation for the surges that occur in FSH secretion during diestrus.     

Influence of Body Condition on Serum Metabolic Indicators of Lipid Mobilization and Oxidative Stress in Dairy Cows During the Transition Period

The objectives of this study were to examine the influence of body condition of cows on metabolic and antioxidative status, as well as to investigate the relationship between metabolic indicators of lipid mobilization and oxidative stress during transition period. The study was conducted on 24 Holstein‐Friesian dairy cows divided into 2 groups according to their body condition score (BCS) as optimal (n = 12; BCS from 3.25 to 3.75) or adipose (n = 12; BCS ≥4). Metabolic status (glucose, triglycerides, total cholesterol, HDL cholesterol, NEFA and BHB), paraoxonase‐1 (PON1) and apolipoprotein A‐I (ApoA‐I) were analysed in sera taken on days ?30, ?10, ?2, 0, 5, 12, 19, 26 and 60 relative to parturition. Adipose cows had significantly higher glucose concentration at parturition being significantly decreased after parturition on days 12 and 19. Total cholesterol and HDL‐C concentrations were the lowest at parturition and significantly higher on days 26 and 60 after parturition in both groups of cows. Both investigated groups had significantly higher NEFA concentration from parturition until day 19 after parturition, indicating energy deficit and an increased lipid mobilization after calving. There were no significant differences in BHB concentration during transition period in both groups. No significant differences were found in PON1 activity and ApoA‐I concentration during transition period in both groups of cows. However, in adipose cows, although not significantly different, PON1 was decreased from calving until day 19 after parturition indicating a disturbance in antioxidative status in adipose cows. PON1 significantly positively correlated with total cholesterol and HDL‐C concentrations and negatively with NEFA indicating a strong relationship of PON1 with lipid metabolism. Significant positive correlation between NEFA and BHB in both groups of cows points out on energy deficit during transition period that cows tend to overcome by lipid mobilization providing alternative source of energy needed for parturition and lactation.     

Relationship between stages of the estrous cycle and bone cell activity in Thoroughbreds

OBJECTIVE: To investigate the relationship between stage of estrous cycle and bone cell activity in Thoroughbreds. SAMPLE POPULATION: Blood samples collected from forty-seven 2-year-old Thoroughbred mares in training for racing. PROCEDURES: Blood samples were collected monthly (in April through September) from the mares. Stage of estrus was determined by assessing serum progesterone concentration. Bone cell activity was determined by measuring concentrations of 2 markers of bone formation (osteocalcin and the carboxy-terminal propeptide of type I collagen [PICP]) and a marker of bone resorption (the cross-linked carboxy-terminal telopeptide of type I collagen [ICTP]) in sera. RESULTS: When the relationship between stage of the estrous cycle and markers of bone cell activity was examined, serum concentrations of both osteocalcin and ICTP were significantly higher in mares that were in the luteal phase, compared with mares that were at other stages of the estrous cycle. Stage of estrus did not affect serum PICP concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that bone cell activity in Thoroughbred mares fluctuates during the estrous cycle; serum concentrations of markers of bone formation and bone resorption are increased during the luteal phase. Further studies are required to determine whether these changes are of clinical importance and increase the risk of injury for mares in training during the breeding season. As in humans, stage of estrus must be considered as a source of uncontrollable variability in serum bone marker concentrations in horses.     

Metabolic and structural abnormalities in dogs with early left ventricular dysfunction induced by incessant tachycardia

OBJECTIVE: To assess morphologic and metabolic abnormalities in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP). ANIMALS: 7 Beagles. PROCEDURE: Plasma carnitine concentrations were measured before and after development of ELVD induced by RRVP. At the same times, transvenous endomyocardial biopsy was performed, and specimens were submitted for determination of myocardial carnitine concentrations and histologic, morphometric, and ultrastructural examination. RESULTS: In 4 dogs in which baseline plasma total carnitine concentration was normal, RRVP induced a decrease in myocardial total and free carnitine concentrations and an increase in myocardial esterified carnitine concentration. In 3 dogs in which baseline plasma total carnitine concentration was low, plasma and myocardial carnitine concentrations were unchanged after pacing. Structural changes associated with pacing included perinuclear vacuolization in 3 dogs. Morphometric analyses indicated there was a decrease in myofiber cross-sectional diameter and area following pacing. Electron microscopy revealed changes in myofibrils and mitochondria following pacing. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that moderate to severe alterations in myocyte cytoarchitecture are present in dogs with ELVD induced by RRVP and that in dogs with normal plasma carnitine concentrations, myocardial carnitine deficiency may be a biochemical marker of ELVD. Results also indicated that transvenous endomyocardial biopsy can be used to evaluate biochemical and structural myocardial changes in dogs with cardiac disease.     

Reproductive traits, lactation and foal growth in mares fed altrenogest

Lactating mares were assigned as controls or fed altrenogest (.044 mg.kg body wt-1.d-1) for 15 d after foaling. Mares (n = 6) fed altrenogest were inseminated during the first estrus after treatment and mares (n = 6) in the control group were inseminated during the second postpartum estrus. Ovulation during the estrus in which mares were inseminated occurred 26 +/- 1 d postpartum for treated mares and 36 +/- 1 d postpartum for control mares. The percentage of mares conceiving was not different for control (67%) and alternogest-treated (100%) mares. No differences were observed in tone and size of the uterus or size of the ovulatory follicle between treated and control groups. Uterine cultures and biopsies collected on d 7 and 15 postpartum were similar between treatment and control groups in bacterial populations or endometrial epithelial cell height. Blood was collected on d 7, 11, 15, 19 and 23 postpartum, and concentrations of estradiol-17 beta in serum were determined by radioimmunoassay. Mean concentrations of estradiol-17 beta across days were 10 +/- .8 and 12 +/- .6 pg/ml for control and treated mares, respectively. Concentrations of serum estradiol-17 beta were higher (P less than .05) in treated mares on d 23 postpartum. Daily milk yields, determined by the weigh-suckle-weigh method, and milk composition were similar between treatment groups on each collection day. Altrenogest can be used to predictably delay estrus in the postpartum mare without altering fertility, yield and composition of milk, or foal growth.     

水牛发情周期生殖激素变化规律及唾液结晶的分析

试验对水牛发情周期血清和唾液中雌二醇(E_2)和孕酮(P_4)的浓度变化规律、水牛唾液结晶与卵泡发育变化分别进行了分析研究,为进一步探讨水牛发情规律、指导生产提供依据。采用酶联免疫分析法(ELISA)测定发情母水牛血清和唾液中E_2和P_4的浓度变化,并对血清和唾液的激素变化规律进行相关性分析。结果表明,水牛血清和唾液中的E_2和P_4呈波动性变化。发情前期,唾液中P_4浓度一直维持在6.50～7.10 ng/mL,发情第13天达到11.09 ng/mL,随后快速下降。唾液中E_2浓度在发情第3～5天出现一个峰值178.53 pg/mL,在第14～17天唾液中E_2浓度显著升高,出现第二个峰值179.10 pg/mL。母水牛唾液中E_2和P_4浓度的变化趋势与其在血清中的变化趋势基本一致,均呈显著相关(P<0.05);唾液中E_2与P_4浓度呈极显著相关(P<0.01)。水牛发情当天唾液结晶呈现明显的蕨类作物形状且分维值显著低于其他时间点(P<0.05)。水牛发情周期唾液结晶图形的变化与卵巢卵泡发育基本同步,可作为监测水牛发情及预测排卵的可靠指标之一。     

Assessment of plasma carnitine concentrations in relation to ceroid lipofuscinosis in Tibetan Terriers

OBJECTIVE: To determine whether the late onset form of inherited ceroid lipofuscinosis (CL) in Tibetan Terriers is accompanied by low plasma carnitine concentrations prior to the appearance of clinical signs. ANIMALS: 129 healthy Tibetan Terriers, 12 Tibetan Terriers with CL, and 95 healthy purebred dogs of other breeds. PROCEDURE: After withholding food, blood samples were collected from all dogs into tubes containing EDTA. Blood samples were analyzed for plasma-free carnitine and acyl-carnitines concentrations. RESULTS: Neither the mean plasma total carnitine concentration nor the mean fraction of carnitine in the free form differed significantly between Tibetan Terriers with CL and healthy Tibetan Terriers. Among Tibetan Terriers and the general dog population, plasma carnitine concentration increased with age. Castrated males had an overall increase in plasma carnitine concentrations and variability, compared with sexually intact males. By comparison, plasma carnitine concentrations were not significantly different between spayed and sexually intact females. The mean plasma carnitine concentration in the Tibetan Terriers was approximately 22% higher than in the general population of healthy dogs of other breeds. CONCLUSIONS AND CLINICAL RELEVANCE: Contrary to what is seen in early onset CL in English Setters and in humans with some forms of CL, plasma carnitine concentrations are not decreased in the late-onset disorder in Tibetan Terriers. Our large-scale study establishes reference range values for plasma carnitine concentrations in dogs as functions of age and sex that will be useful in evaluating potential carnitine deficiencies in other disorders in dogs.     

Feeding animal fats to sheep.

In an experiment lasting 7 weeks, 18% of the calculated energy requirement of 5 nonpregnant ewes was met by giving natural fats of animal origin mixed in the ration (at a level of 6.6%). Changes in certain blood and blood plasma parameters of lipid and energy metabolism were monitored at 5 time-points during the experiment. Samples of rumen fluid were taken three times for determining the concentrations of volatile fatty acids (VFA). Rumen fermentation was studied by in sacco method. Total lipid (TL) content of the liver and fatty acid composition of the liver tissue and subcutaneous adipose tissue (from the tailhead) were analyzed at the beginning and at the end of the experiment. At the concentration used in this experiment, fat supplementation caused neither digestive disturbances nor any other adverse changes in the animals' health status. It did, however, exert a significant influence on blood plasma lipid composition. TL and total cholesterol (TCh) concentration increased and blood glucose level decreased. A rise in triglyceride (TG) content was accompanied by a drop in free fatty acid (FFA) concentration. The in sacco experiments and volatile fatty acid (VFA) levels in the rumen fluid suggested an impaired crude fibre digestion in the rumen. At the same time, fat supplementation enhanced rumen proteolysis. The TL content of liver samples did not exceed the physiological limit. The liver biopsy samples had decreased myristic acid and increased stearic and oleic acid concentrations. No change occurred in the fatty acid composition of the fat depots.     

An investigation of the relationships between body condition and plasma lipid and lipoprotein concentrations in 24 donkeys

Obese donkeys are susceptible to a hyperlipaemic crisis characterised by high plasma triglyceride concentrations. In this study, the relationships between the body condition of 24 donkeys and their basal lipid metabolism were investigated. Plasma cholesterol, triglyceride and lipoprotein cholesterol concentrations were measured in healthy donkeys classified according to their body condition as thin, ideal or obese. There were significant differences between the groups in the concentrations of triglyceride and very low density lipoprotein (VLDL), which increased in concentration with body condition (P less than 0.05). Cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) concentrations were similar in all the groups. Triglyceride and VLDL concentrations were positively correlated with body weight (r = 0.82) and plasma free fatty acid concentration (r = 0.48). There were no significant differences in basal plasma concentrations of insulin or cortisol. These results suggest that obesity in donkeys is associated with changes in lipid and lipoprotein metabolism that might predispose the animals to hyperlipaemia.