Studies on volatile oils compounds of Acorus macrospadiceus based on GC-MS, an ethnomedicinal and food plant used by local people in southwest China / 中国中药杂志

Acorus macrospadiceus is a common medicinal and food plant used different ethnic groups in Guizhou and surrounding areas. In this paper, the leaf and rhizome tissues of A. macrospadiceus were hydro-distilled to extract the volatile oils. The chemical constituents of these oils were analyzed by GC-MS and identified using the NIST 14.0 & NIST 14.0s mass spectral libraries. The relative contents of chemical constituents from the different plant parts were determined by area normalization. The analysis of A. macrospadiceus volatile oils resulted in the identification of 25 compounds from the leaf and 36 compounds from the rhizome. The identified compounds accounted for 97.85% of the leaf essential oil content and 97.18% of the rhizome essential oil content. The main volatile constituent of A. macrospadiceus was identified as estragole (93.56% of total oil content in leaf and 71.62% of total oil content in rhizome). Fourteen compounds were found to be common to essential oils of both leaf and rhizome. However, the relative amounts of these compounds were significantly different between the plant parts; the remaining identified compounds were unique to each part. This comparison of volatile oils from the different parts of A. macrospadiceus can serve as a reference for future development. Because of the higher estragole content and better harvesting sustainability of the leaves compared to rhizomes, the leaves of A. macrospadiceus deserve consideration for sustainable development. However, when we use it as a medical plant, we should draw a distinction between it with A. tatarinowii.

Long-term follow-up of patients with spontaneous clearance of hepatitis C: does viral clearance mean cure?

Up to 40% of patients with hepatitis C virus (HCV) antibodies are negative for HCV RNA at initial evaluation. If there is a risk of viral re-activation, long term follow-up is required with attendant financial, psychological and medical implications. We investigated the risk of re-activation in the Irish anti-D cohort. Information was obtained from the national hepatitis C database which includes data on patients infected by anti-D immunoglobulin in two large outbreaks, 1977-9 and 1991-94. As part of a screening programme, starting in 1994, 64,907 females exposed to anti-D immunoglobulin were evaluated. Three hundred and forty-seven were found to be antibody positive but HCV RNA negative at initial assessment. 93% had subsequent RNA tests. There was no evidence of HCV recurrence in patients whose infection resolved spontaneously. It appears that two initial sequential negative results for HCV RNA are sufficient to confirm spontaneous viral clearance and probable cure of hepatitis C virus infection.

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production.

It was hypothesized that differences in starch degradability account for observed differences in rumen vaccenic acid (t11-18:1) and milk rumenic acid (RA) concentrations. To test this hypothesis, starch degradability was varied through grain source and by processing. Eight Holstein cows in mid-lactation were assigned to two 4 × 4 Latin squares with four 21-day periods and four diets: dry rolled barley, ground barley, dry rolled corn and ground corn. Diets contained similar starch content and were supplemented with whole sunflower seed to provide similar total polyunsaturated fatty acid (PUFA) (18:2n-6 + 18:3n-3) contents. Forage/concentrate ratios of all diets were 42 : 58. Rumen, plasma and milk samples were collected in the third week of each period. In situ degradation rates (%/h) for rolled corn, ground corn, rolled barley and ground barley were 5.4, 8.9, 17.0 and 19.4, respectively, for dry matter (DM) and 6.3, 10.8, 25.3 and 43.8, respectively, for starch. DM intakes were greater for corn-based diets (CBD) than for barley-based diets (BBD) with no difference between rolled and ground diets. Daily minimum rumen pH was less (5.2 v. 5.5) and pH duration <5.8 (h/d) was greater (7.4 v. 4.3) for BBD than for CBD. Milk fat content and yield were less for BBD than for CBD with greater values observed for rolling compared with grinding. Variability in milk fat yield was strongly related (R2 = 0.55; P < 0.01) to total starch intake (45%) and milk c9t11-CLA (10%) and none of the t-18:1 isomers or CLA isomers that are typically associated with milk fat depression entered the model. The concentrations (%) of t10-18:1 and t11-18:1 were greater for BBD than for CBD in rumen contents (t10-18:1, 3.5 v. 1.3; t11-18:1, 3.2 v. 1.9), plasma (t10-18:1, 1.2 v. 0.2; t11-18:1, 0.97 v. 0.58) and milk (t10-18:1, 3.8 v. 1.0; t11-18:1, 2.6 v. 1.7) despite greater total PUFA intakes for CBD. Milk RA concentration was greater for BBD than for CBD (1.46 v. 0.89) but was not influenced by the method of grain processing. This study clearly demonstrated that the milk content and profile of t-18:1 and CLA isomers were more strongly influenced by the source of grain starch (barley > corn) than by the method of grain processing indicating that factors inherent in the source of starch were responsible for the observed differences and these factors could not be modified by the processing methods used in this study.

Causation in occupational injury.

Assessment for compensation of occupational injury forms is commonplace for occupational medicine specialists and less frequently for other health-care providers. There is no specific training to understand the legal system that forms the basis of any compensation system. This paper sets out a process for judging medical scientific evidence in cases of suspected occupational injury or disease. The process is confusing for medical and legal professionals because of the lack of a common understanding. Understanding the concepts of balance of probabilities and scientific probability is essential for clarity of approach. There is an inevitable conclusion that cause of occupational injury or disease in each case will rest on a sequential consideration of general and specific cause.

Grazing cows are more efficient than zero-grazed and grass silage-fed cows in milk rumenic acid production.

Six rumen-cannulated Holstein cows in early lactation were assigned to 3 treatments: grazing (G), zero-grazing (ZG), and grass silage (GS) harvested from the same perennial rye grass sward in a 3 x 3 Latin square design with three 21-d periods. The objectives of this study were to investigate the underlying mechanisms for the reported elevation in milk rumenic acid (RA) concentration associated with G compared with ZG and GS, and to identify the important variables contributing to the milk RA response. Grazing animals were offered 20 kg of dry matter/cow per day; indoor animals were offered ad libitum grass or silage. A concentrate at a rate of 3 kg/d was also offered to all cows. Rumen, plasma, and milk samples were collected in the third week of each period. Data were analyzed by the MIXED procedure of SAS. Dry matter intakes were less for GS with no difference between G and ZG. Milk yield was greater for G than for ZG or GS. Milk fat and protein contents were less for GS with no difference between G and ZG. The combined intake (g/d) of linoleic and linolenic (18:3n-3) acids was different across the treatments (G: 433; ZG: 327; and GS: 164). Rumen pH was less for G with no difference between ZG and GS. Concentrations of volatile fatty acids and ammonia nitrogen in rumens were not different across the treatments. Wet rumen fill was less for G with no difference between ZG and GS. Vaccenic acid concentrations were different across the treatments in rumen (G: 12.30%, ZG: 9.31%, and GS: 4.21%); plasma (G: 2.18%, ZG: 1.47%, and GS: 0.66%) and milk (G: 4.73%, ZG: 3.49%, and GS: 0.99%). Milk RA concentrations were greater for G (2.07%) than for ZG (1.38%) and GS (0.54%). Milk desaturase index based on the ratio cis-9-14:1/14:0 was not different across the treatments. Milk RA yield per 100 g of linoleic acid and linolenic acid intake (efficiency) was 2.23, 1.50, and 0.62 g in G, ZG, and GS, respectively, suggesting that G cows were more efficient than ZG and GS cows in milk RA production. Stepwise regression analysis of a group of variables revealed that plasma vaccenic acid accounted for 95% of the variation in milk RA production. Milk desaturase index did not enter into the model. Overall findings suggest that substrate intake influenced milk RA production but it was not the only factor involved. There were differences in efficiency of milk RA production, which appears to depend on the factors regulating ruminal vaccenic acid production and its supply to the mammary tissue.

Effects of dietary energy and protein density on plasma concentrations of leptin and metabolic hormones in dairy heifers.

The hormonal and metabolic signals that communicate the level of body energy reserves to the reproductive-mammary axis remain undefined in dairy cattle; consequently, our hypothesis was that leptin may fulfill this role. Our objectives were to determine the effects of diets differing in energy and protein density on dry matter intake (DMI), growth traits [body weight (BW), body condition score (BCS), back-fat (BF) thickness], and temporal changes in plasma concentrations of leptin, insulin, growth hormone (GH), insulin-like growth factor-1 (IGF-1), glucose, and nonesterified fatty acids (NEFA) in dairy heifers during the pre- and postpubertal periods. In period 1, heifers were randomly allotted (n = 10/diet) at 103 kg of BW to diets for a predicted average daily gain of 1.10 (high, H), 0.80 (medium, M), or 0.50 kg/d (low, L). Five heifers in each of the H and L groups were further studied during period 2, either at 12 mo of age (HA, LA) or at 330 kg of BW (HW, LW). The data provide evidence that 1) DMI (18%), BW (17%), and BF (5%) together explained 40% of the variation in plasma leptin concentrations (r(2) = 0.396); 2) unlike the acute postprandial increase in plasma insulin as a result of increased nutrient density (H 1.42 +/- 0.09, M 1.02 +/- 0.09, L 0.68 +/- 0.11 ng/mL), plasma leptin concentrations did not respond acutely with a distinct postprandial profile; 3) although plasma leptin concentrations increased with age, leptin at puberty did not differ among treatment groups (H 5.63 +/- 2.48, M 4.28 +/- 0.55, L 4.12 +/- 0.72 ng/mL) and there was no evidence of an abrupt transition in prepubertal plasma leptin concentrations; 4) plasma leptin concentrations may not be a critical trigger for puberty in rapidly growing heifers, but are apparently essential for puberty in heifers with normal or restricted growth rates; and 5) plasma concentrations of insulin (H 0.59 +/- 0.07, M 0.43 +/- 0.09, L 0.30 +/- 0.09 ng/mL), IGF-1 (H 151.08 +/- 16.47, L 82.51 +/- 17.47 ng/mL), and glucose (H 81.35 +/- 3.39, M 73.59 +/- 2.34, L 68.25 +/- 3.39 mg/dL) reflected nutrient density, whereas GH (H 1.82 +/- 0.23, L 5.87 +/- 0.45 ng/mL) and NEFA (H 209.54 +/- 50.83, L 234.93 +/- 48.97 microM) were inversely related to the plane of nutrition. Collectively, these data suggest that plasma concentrations of leptin may play a role in long-term regulation of energy reserves and puberty in growing Holstein heifers.

Evaluating the conjugated linoleic acid and trans 18:1 isomers in milk fat of dairy cows fed increasing amounts of sunflower oil and a constant level of fish oil.

The objective was to evaluate different levels of sun-flower oil (SFO) in dairy rations to increase vaccenic (trans-11-18:1) and rumenic acids (cis-9,trans-11-18:2) in milk fat, and assess the content and composition of other trans-octadecenoic (trans-18:1) and conjugated linoleic acids (CLA) isomers. Eighty lactating Holstein cows were fed control diets for 4 wk and then placed on 4 diets for 38 d; milk fat was analyzed after 10 and 38 d. The treatments were: control, 1.5% SFO plus 0.5% fish oil (FO), 3% SFO plus 0.5% FO, and 4.5% SFO plus 0.5% FO. The forage-to-concentrate ratio was 50:50 and consisted of barley/alfalfa/hay silage and corn/barley grain concentrate. There were no differences in milk production. Supplementation of SFO/FO reduced milk fat compared with respective pretreatment periods, but milk protein and lactose levels were not affected. There was a linear decrease in all short- and medium-chain saturated fatty acids (SFA) in milk fat after 10 d (25.5, 24.1, 20.2, and 16.7%) and a corresponding linear increase in total trans-18:1 (5.2, 9.1, 14.1, and 21.3%) and total CLA (0.7, 1.9, 2.4, and 3.9%). The other FA in milk fat were not affected. Separation of trans-18:1 isomers was achieved by combination of gas chromatography (GC; 100-m highly polar capillary column) and prior separation of trans FA by silver ion-thin layer chromatography followed by GC. The CLA isomers were resolved by a combination of GC and silver ion-HPLC. The trans-11- and trans-10-18:1 isomers accounted for approximately 50% of the total trans-18:1 increase when SFO/FO diets were fed. On continued feeding to 38 d, trans-11-18:1 increased with 1.5% SFO/FO, stayed the same with 3%, and declined with 4.5% SFO/FO. Rumenic acid showed a similar pattern on continued feeding as trans-11-18:2; levels increased to 0.43, 1.5, 1.9, and 3.4% at 10 d and to 0.42, 2.15, 2.09, and 2.78% at 38 d. Rumenic acid was the major CLA isomer in all 4 diets: 66, 77, 78 and 85%. The CLA isomers trans-7,cis-9-, trans-9,cis-11-, trans-10,cis-12-, trans-11,trans-13-, and trans-9,trans-11-/trans-10,trans-12-18:2 also increased from 0.18 (control) to 0.52% (4.5% SFO/FO). Milk fat produced from 3% SFO/FO appeared most promising: trans-11-18:1 and cis-9,trans-11-18:2 increased 4.5-fold, total SFA reduced 18%, and moderate levels of trans-10-18:1 (3.2%), other trans-18:1 (6.6%) and CLA isomers (0.5%) were observed, and that composition remained unchanged to 38 d. The 4.5% SFO/FO diet produced higher levels of trans-11-18:1 and cis-9,trans-11-18:2, a 28% reduction in SFA, and similar levels of other trans-18:1 (9.2%) and CLA isomers (0.52%), but the higher levels of trans-11-18:1 and cis-9,trans-11-18:2 were not sustained. A stable milk fat quality was achieved by feeding moderate amounts of SFO (3% of DM) in the presence of 0.5% FO that had 4% vaccenic and 2% rumenic acids.

Effect of safflower oil, flaxseed oil, monensin, and vitamin E on concentration of conjugated linoleic acid in bovine milk fat.

Conjugated linoleic acid (CLA) refers to a mixture of conjugated octadecadienoic acids of predominantly ruminant origin. The main isomer in bovine milk fat is the cis-9, trans-11 CLA. Interest in CLA increased after the discovery of its health-promoting properties, including potent anticarcinogenic activity. Two experiments were conducted to evaluate dietary strategies aimed at increasing the concentration of CLA in bovine milk fat. Both experiments were organized as a randomized complete block design with a repeated measures treatment structure. In Experiment 1, 28 Holstein cows received either a control diet or one of 3 treatments for a period of 2 wk. The control diet consisted of 60% forage (barley silage, alfalfa silage, and alfalfa hay) and 40% concentrate on a dry matter (DM) basis, fed as a total mixed ration (TMR). The concentrate was partially replaced in the treatment groups with 24 ppm of monensin (MON), 6% of DM safflower oil (SAFF), or 6% of DM safflower oil plus 24 ppm of monensin (SAFF/M). Average cis-9, trans-11 CLA levels in milk fat after 2 wk of feeding were 0.45, 0.52, 3.36, and 5.15% of total fatty acids for control, MON, SAFF, and SAFF/M, respectively. In Experiment 2, 62 Holstein cows received either a control diet or one of 5 treatment diets for a period of 9 wk. The control diet consisted of 60% forage (barley silage, alfalfa silage, and alfalfa hay) and 40% concentrate on a DM basis, fed as a TMR. The concentrate was partially replaced in the treatment groups with 6% of DM safflower oil (SAFF), 6% of DM safflower oil plus 150 IU of vitamin E/kg of DM (SAFF/E), 6% of DM safflower oil plus 24 ppm of monensin (SAFF/M), 6% of DM safflower oil plus 24 ppm of monensin plus 150 IU of vitamin E/kg of DM (SAFF/ME), or 6% of DM flaxseed oil plus 150 IU of vitamin E/kg of DM (FLAX/E). Average cis-9, trans-11 CLA levels during the treatment period were 0.68, 4.12, 3.48, 4.55, 4.75, and 2.80% of total fatty acids for control, SAFF, SAFF/E, SAFF/M, SAFF/ME, and FLAX/E, respectively. The combination of safflower oil with monensin was particularly effective at increasing milk fat CLA. The addition of vitamin E to the diet partially prevented the depression in milk fat associated with oilseed feeding, but had no significant effect on the concentration of CLA in milk.

Effects of bovine somatotropin on beta-casein mRNA levels in mammary tissue of lactating cows.

Bovine somatotropin (bST) increases milk production in lactating cows through its effect on nutrient partition and maintenance of mammary cell function. A positive relationship between bST treatment and abundance of beta-casein mRNA in mammary tissues from lactating cows was hypothesized. In mammary tissue isolated from 14 midlactation Holstein cows, beta-casein mRNA was 35.4% higher among 7 cows receiving continuous bST infusions at 29 mg/d for 63 d compared with tissue from 7 untreated control cows. To investigate whether increased beta-casein mRNA resulted from a direct effect of bST on the mammary gland, explants of mammary tissue from other lactating cows that had not received bST were incubated with bST and prolactin in 2 experiments. Mammary explant cultures taken from 2 lactating cows that had not been milked for 48 h were supplemented with either prolactin or bST. Both prolactin and bST stimulated higher levels of beta-casein mRNA in the mammary explants compared with their non-supplemented counterparts. Explant cultures from 4 additional lactating cows were prepared from rear quarter mammary tissue subjected to milking intervals of 6 h for right rear quarters or 20 h for left rear quarters. Both bST- and prolactin-mediated increases in beta-casein mRNA were dependent on milking intervals. That is, levels of beta-casein mRNA were increased by bST or prolactin supplementation in explants isolated from the mammary quarters biopsied 20 h after milking but not for those biopsied at 6 h after milking. Results are consistent with a potential role for bST in up-regulating or sparing beta-casein mRNA levels in lactating bovine mammary tissue in a manner similar to prolactin.

Milk protein synthesis as a function of amino acid supply.

Most prediction schemes of milk protein secretion overestimate milk protein yield from dairy cows at high protein intakes, thereby overestimating milk protein yield response to protein supplementation. This study was conducted to determine factors contributing to such an overestimation. Using published studies, a database was constructed that was limited to amino acid (AA) infusion studies, as then only the digestible amino acid of dietary origin needed to be estimated, whereas the amount infused was known exactly, thereby reducing the dependence on estimated values. Although milk protein yield was positively related with total energy supply, and both digestible duodenal supply and infused AA, in this database there was no relationship between milk protein yield response above control treatments and the nutrient status of the cows (energy or protein). Total milk protein yield was defined as a function of individual AA supply, using a segmented-linear and a logistic model to obtain estimates of the efficiency of conversion of AA into milk protein. Except for Lys and Met supply, the segmented-linear model yielded lower root mean square error and better correlation, but both models were similar in their reliability. For both models, the estimated efficiency of conversion of AA to milk differed among AA. Estimations of the ideal profile of AA for lactating dairy cows were similar between models, with requirements for Lys and Met in line with 2001 National Research Council recommendations. The major difference is that the segmented-linear model yields a constant efficiency of conversion of an AA until requirements are met, with zero efficiency beyond this point. The logistic model allows for an estimation of the decreasing marginal efficiency of conversion of AA as the supply approaches the requirements. The use of variable efficiency factors should improve our ability to predict protein yield in response to supplemental protein.

Adjustable and fixed dosing with budesonide/ formoterol via a single inhaler in asthma patients: the ASSURE study.

Patient-guided management of asthma using adjustable dosing of budesonide/formoterol in a single inhaler (Symbicort) was compared with fixed dosing in an open-label, multicentre, randomised study. Patients, uncontrolled on an inhaled corticosteroid (ICS) or controlled on an ICS and a long-acting beta2-agonist, entered a 4-week run-in period and received budesonide/formoterol (80/4.5 or 160/4.5 microg), 2 inhalations b.i.d. Following randomisation, the fixed-dosing group (n = 764) continued this regimen for a further 12 weeks. The adjustable-dosing group (n = 775) could step down to 1 inhalation b.i.d. if symptoms were controlled, and, at early signs of worsening symptoms, promptly step up to 4 inhalations b.i.d. for < or = 2 weeks. During run-in, National Heart, Lung and Blood Institute symptom-severity grading was maintained in 60% and improved in 31% of patients, clinic peak flow increased from 400 to 4191/min (P<0.001), and health-related quality of life (overall MiniAQLQ) improved from 4.6 to 5.4 (P<0.001). Patients effectively used the adjustable-dosing regimen; 79% reduced budesonide/formoterol dosage and, compared with fixed dosing, the number of inhalations were significantly lowered (3.2 vs. 3.8 inhalations/day, P<0.05). Both regimens were well tolerated. In both groups, symptom control was maintained or improved in 85-86% of patients, and 94% experienced no treatment failures. Consistent with current guidelines, adjustable maintenance dosing with budesonide/formoterol in a single inhaler provides effective asthma control at reduced medication doses.

Effect of short-term fasting on plasma concentrations of leptin and other hormones and metabolites in dairy cattle.

We determined the effects of short-term fasting and refeeding on temporal changes in plasma concentrations of leptin, insulin, insulin-like growth factor- 1 (IGF-1), growth hormone (GH), glucose, and nonesterified fatty acids (NEFA), in early lactating cows, non-lactating pregnant cows, and postpubertal heifers. In experiment 1, Holstein cows in early lactation were either fed ad libitum (Control, n=5) or feed deprived for 48 h (Fasted, n=6). Plasma leptin, insulin, and glucose concentrations rapidly declined (P<0.05) within 6h, and IGF-1 by 12h, but all these variables sharply returned to control levels (P>0.10) within 2h of refeeding. Plasma NEFA and GH concentrations were elevated (P<0.05) by 4 and 36 h of fasting and returned to control levels (P>0.10) by 8 and 24h after refeeding, respectively. In experiment 2, four ruminally cannulated pregnant non-lactating Holstein cows were used in a cross-over design and were fasted for 48 h (Fasted) or fasted with partial evacuation of rumen contents (Fasted-Evac). The plasma variables measured did not differ (P>0.10) between Fasted and Fasted-Evac cows. Plasma leptin, insulin, and IGF-1 concentrations were reduced by 10, 6, and 24h of fasting, respectively, in Fasted-Evac cows; and these variables were reduced by 24h in Fasted cows (P<0.05). Plasma glucose levels were reduced (P<0.05) by 48 h of fasting in both groups of fasted animals. Plasma NEFA and GH levels were increased (P<0.05) by 12 and 48 h of fasting, respectively. In experiment 3, postpubertal Holstein heifers were either fed ad libitum (Control, n=4) or feed deprived for 72 h (Fasted, n=5). Concentrations of leptin, insulin, IGF-1, and glucose in plasma were reduced (P<0.05) by 24, 10, 24, and 48 h of fasting, respectively. Plasma NEFA concentrations increased (P<0.05) by 4h, of fasting while GH levels were not significantly (P>0.10) affected by fasting. Collectively, our data provide evidence that plasma leptin concentrations are reduced with short-term fasting and rebound on refeeding in dairy cattle with the response dependent on the physiological state of the animals. Compared to the rapid induction of hypoleptinemia with fasting of early lactation cows, the fasting-induced hypoleptinemia was delayed in non-lactating cows and postpubertal heifers.

Short communication: Tissue distribution of leptin and leptin receptor mRNA in the bovine.

Detection of leptin and leptin receptor mRNA in various tissues is crucial to an understanding of leptin physiology in dairy cattle. We report here evidence of leptin receptor gene expression in central and peripheral tissues of the bovine by reverse transcription and polymerase chain reaction analysis. Leptin mRNA was detectable in mammary parenchyma and in adipose tissue with similar transcript abundance among the subcutaneous, pericardial, perirenal, and mesenteric adipose depots. The mRNA for the long-form of the leptin receptor, Ob-Rb, was detectable in all four adipose depots, mammary parenchyma, semintendinosus muscle, liver, adrenal cortex, spleen, kidney, testis, mesenteric lymph node, lung, aorta, abomasum, duodenum, jejunum, ileum, hypothalamus, pituitary, brain stem, cerebral cortex, cerebellar cortex, pons, and pineal gland. The mRNA for the short form of the leptin receptor, Ob-Ra, was detectable in the liver, adrenal cortex, spleen, pituitary, and brain stem, but not in the other tissues surveyed. The wide spectrum of tissues expressing the leptin receptor gene reveals that leptin may have multiple physiological functions in the bovine.

Effect of dietary energy and protein density on body composition, attainment of puberty, and ovarian follicular dynamics in dairy heifers.

The objectives were to examine the effects of dietary energy and protein density on age and body composition at puberty, and on ovarian follicular dynamics during the pre- and peripubertal periods in Holstein heifers. In Phase 1, heifers were randomly allotted (n=10 per diet) at 100 kg body weight (BW) to diets with either low (P1L), medium (P1M) or high (P1H) energy and protein formulated for an average daily gain (ADG) of 0.5, 0.8 or 1.1 kg per day, respectively. During Phase 2 (P2), all heifers were fed ad libitum a common diet formulated for an ADG of 0.8 kg per day. Half the animals within the high (n=5) and low groups (n=5) entered P2 either at 12 months of age (P2H-12; P2L-12) or at 330 kg BW (P2H-330; P2L-330). Heifers fed P1H, P1M, P1L, and P2L-12 diets attained puberty at approximately 9, 11, 16, and 14 months of age, respectively (P<0.01). Urea space estimates of body fat and protein percent, and back-fat thickness, were lower in P1L heifers compared to P1H or P1M heifers at similar chronological ages (P<0.05) but did not differ at puberty (P>0.10). Compared to P1L heifers, P1H heifers had high amplitude LH pulses at 8 months, and high frequency low amplitude LH pulses at 10 months of age (P<0.05). The mean diameter (mm) of the dominant follicle was smaller (P<0.05) in P1L heifers (10.6) compared to P1H (12.8) or P1M (12.2) heifers at 8 months. Maximum size and growth rate of the nonovulatory dominant follicle increased with age (P<0.05) but did not differ between P1H and P1M heifers at puberty. The diameter (mm) of the nonovulatory dominant follicle, and the first and second ovulatory follicles were larger in P2L-12 heifers (14.0, 14.7, and 14.9) compared to P1M heifers (13.1, 12.5, and 11.9), while the peak progesterone levels and CL growth were lower (P<0.05) in the first cycle. In conclusion, dairy heifers attained puberty at a constant body weight and body composition independent of dietary manipulation, the size of dominant follicles increased with age in association with increased LH support, and heifers realimented from a low energy diet developed larger first ovulatory follicles and smaller CL with lower peak progesterone concentrations in the first cycle.

Short communication: Postruminal infusion of conjugated linoleic acids negatively impacts milk synthesis in Holstein cows.

In view of the potential of rumen-protected conjugated linoleic acid (CLA) as a means to increase the CLA content of bovine milk, a study was undertaken to evaluate the effect of synthetic CLA on milk production and composition. Four Holstein cows received abomasal infusion of: 1) control, no lipid infusion, 2) 150 g/d of synthetic CLA, 31.7% cis-9, trans-11; 30.4% trans-10, cis-12, 3) 150 g/d of safflower oil, and 4) 150 g/d of tallow. Infusion was carried out for 20 to 22 h/d for 11-d periods in a 4 x 4 Latin square design. The milk fat concentration of cis-9, trans-11 and trans-10, cis-12 isomers of CLA was significantly increased with infusion of CLA. However, CLA infusion had other unexpected effects on milk production and composition. Milk yield dropped significantly during the period of CLA infusion. Furthermore, as well as the typical depression in milk fat reported with trans-10 isomers of CLA, other negative effects specific to CLA infusion were observed including a drop in lactose concentration and yield, a drop in protein yield, and an elevated somatic cell count. The important difference between synthetically produced CLA and CLA produced naturally in the cow is the much higher proportion of trans-10 isomers of CLA in the former. The results of this study suggest that the extent of enrichment possible for trans-10 isomers of CLA, and hence the usefulness of synthetic CLA for this purpose, may be limited because of unacceptable effects on milk yield and composition.

Peripartum performance and metabolism of dairy cows in response to prepartum energy and protein intake.

Twenty-six multiparous Holstein cows were used to examine the effects of prepartum energy and protein intake on periparturient metabolism and lactation performance. Two levels of energy, 1.65 Mcal/kg of net energy for lactation (NEL) and 1.30 Mcal/kg of NEL, and two levels of protein, 17.0% CP and 12.5% CP, were tested according to a factorial arrangement in a randomized block design. Dietary treatments were fed ad libitum from 21 d before expected calving date to the day of calving. After calving, all cows were fed the same diet. Increased nutrient density did not affect prepartum feed intake, but postpartum intake was higher for cows fed the high-energy diets. Treatment had no effect on cow body weight and body condition score, however, cows fed the high-energy diets were in greater energy balance throughout the study. Milk and milk component yields were unaffected by treatment. Cows fed the high-energy diets had lower plasma nonesterified fatty acid concentrations than cows fed the low energy diets (354.3 vs. 439.9 mumol/L). Hepatic triglyceride concentrations were lower for cows on the high-energy diets than for those on the low-energy diets. Liver glycogen was unaffected by treatment. Acetyl-CoA carboxylase and fatty acid synthase abundance was significantly lower at calving than pretreatment, and higher for cows on the high-energy diets relative to those on the low-energy diets. The activity of acetyl-CoA carboxylase and lipoprotein lipase was greatly decreased with the onset of lactation. Increased protein intake prepartum resulted in elevated plasma beta-hydroxybutyrate concentrations postpartum. Prepartum plasma urea nitrogen was increased and 3-methylhistidine decreased by the high protein treatments. Overall, increased energy density of prepartum diets had beneficial effects on feed intake and lipid metabolism but did not improve lactation performance. Increasing the protein content of the prepartum diet did not appear to confer any advantages to cow productivity.

Influence of carbohydrate source and buffer on rumen fermentation characteristics, milk yield, and milk composition in late-lactation Holstein cows.

The effects of concentrate-to-forage ratio and buffer on rumen fermentation and production parameters were examined in four rumen-cannulated cows (240 +/- 18 d in milk) fed a total mixed ration ad libitum in a 4 x 4 Latin square design. The treatments were a 50:50 concentrate to forage ratio with [1.2% of dry matter, (DM)] and without (0% of DM) buffer and a 75:25 concentrate to forage ratio with (1.2% of DM) and without (0% of DM) buffer. Rumen pH declined in response to increased concentrate but was not influenced by buffer. In the absence of the buffer, rumen acetate declined and propionate was elevated at the higher level of concentrate inclusion. The milk fat concentration was lower for cows fed the high concentrate diet without buffer; however, the addition of buffer to the diet prevented the milk fat depression. Milk fat depression was associated with elevated trans-C18:1 fatty acids in milk, which provides additional support for an inhibitory effect of these fatty acids on mammary fat synthesis. We concluded that the potential of nutrition as a tool to alter milk composition is greater in later lactation as these animals are better able to cope with the negative effects of high grain diets, and the treatment response is greater than in early lactation.

Building the analytic capacity of the State Maternal and Child Health workforce--a history of the HRSA/MCHB Academic Partnership.

The Maternal and Child Health Bureau of the Health Resources and Services Administration (HRSA) in conjunction with Schools of Public Health has sponsored a variety of graduate education and continuing education initiatives during the last 15 years aimed at enhancing the analytic capacity of the maternal and child health (MCH) workforce. These initiatives are described, with lessons learned as well as recommendations for future efforts provided.

Effects of forage source and amount of concentrate on rumen and intestinal digestion of nutrients in late-lactation cows.

The objectives of this study were to determine the effects of dietary forage source with two concentrate concentrations on dry matter (DM) intake, rumen fill, ruminal and intestinal digestibility of nutrients, and duodenal N fractions in lactating cows. Four rumen and duodenal cannulated Holstein cows in late lactation were used in 4 x 4 Latin square design experiment with 21-d periods. Diets were 1) 65% first-cut alfalfa silage and 35% concentrate, 2) 50% alfalfa and 50% concentrate, 3) 65% bromegrass silage and 35% concentrate, and 4) 50% bromegrass and 50% concentrate. Dry matter intake was not affected by forage source but tended to be (P = 0.08) higher for cows fed diets with 50% concentrate. Rumen fill was greater (P < 0.01) for cows fed bromegrass compared with those fed alfalfa silage. Ruminal and intestinal digestion of DM was not affected by dietary forage source or concentrate level. Total N intake was greater for cows fed alfalfa-based diets, reflecting the higher crude protein content of alfalfa. However, total N flow at the duodenum was not affected by either forage source or concentrate in the diet. Although forage source influenced the site of digestion of some nutrients no significant effects on total tract digestibilities were observed.

Milk fatty acid composition and mammary lipid metabolism in Holstein cows fed protected or unprotected canola seeds.

Six midlactation Holstein cows were fed a total mixed ration supplemented with either 4.8% canola meal, 3.3% unprotected canola seeds plus 1.5% canola meal, or 4.8% formaldehyde-protected canola seeds, according to a double 3 x 3 Latin square design. Each period lasted 3 wk; experimental analyses were restricted to the last week of each period. Mammary biopsies were taken the last day of each period for gene expression measurements. Milk production and milk protein percentage were reduced by canola seeds, whether protected or unprotected. Protected canola seeds also decreased dry matter intake. Feeding canola seeds reduced the content of C8 to C16 fatty acids in milk and increased the content of oleic acid (C18:1c9). Unprotected canola seeds elevated the concentrations of C18:0. Protected canola seeds increased the C18:2 and C18:3 content, and reduced the C18d:0/C18:1c9 ratio. Similar results were obtained for plasma fatty acids, with some specific features, such as an increased C16:0/C16:1 ratio with protected canola seeds. Canola seeds had no significant effects on insulin, triglycerides, or cholesterol present in serum, but increased the concentration of nonesterified fatty acids; a greater increase was obtained with protected canola seeds. Expression levels of acetyl-CoA carboxylase and delta 9-stearoyl-CoA desaturase genes measured in the mammary gland did not differ significantly between diets. Therefore, the reduced C18s:0/C18:1c9 ratio observed in milk with protected canola seeds was not due to an enhanced expression of the delta-9 desaturase in the mammary gland.