Effect of twinning on the feed intake, performance and health of dairy cows

The aim of this study was to assess the effect of bearing twins on the health and performance of dairy cows. Data from twin-bearing Holstein Friesian cows at the Langhill Dairy Research Centre between January 1990 and July 2002 were compared to single-bearing cows to determine if there was any significant difference in milk production, feed intakes, health and fertility. There were 122 twin births (from 104 different cows) in the Langhill herd, a rate of 4.7% during the study period.

The incidence of twinning was higher in high genetic merit cows (select genetic line cows) and increased with parity (r = 0.870, P < 0.01). Compared to a single-bearing cow, a twin pregnancy was associated with a shorter gestation period, an increased chance of a retained placenta after calving and a poorer body condition score post-calving. The post-calving condition score of twin-bearing cows was negatively correlated with the total weight of calves born (r = − 0.235, P < 0.05). Twin-calving cows also had significantly more dystocia, a higher chance of having a dead calf, an increased number of days from calving to their first observed heat and number of days from calving to their first service. Dystocia was positively correlated with the number of dead calves at birth (r = 0.309, P < 0.01) and with the total weight of calves born (r = 0.211, P < 0.05). Twin-bearing cows on a low-concentrate diet had an increased chance of having metritis and/or endometritis compared to single-bearing cows on the same diet. There was no significant difference in the reason for culling or the time at which cows were culled post-calving, however, twin-bearing cows on a low-concentrate diet were 3.2 times more likely to be culled than a single-bearing cow, with cows on a high-concentrate diet having equally high levels of culling. There were no significant differences between twin- and single-producing cows' mean daily feed intakes, daily milk yields, total milk yields and milk fat and protein compositions during early, mid and late lactation pre and postpartum on a low- or high-concentrate diet. The body condition and drying off period of twin pregnant cows should be managed to avoid post-calving health and performance problems.     

Effect of prepartum compensatory nutrition regimen on metabolism and performance of dairy cows

The impact of closely controlled energy management during the dry period upon general peripartum metabolism and the subsequent lactation was evaluated in multiparous dairy cows. Eight lactating, pregnant Holstein cows were paired according to current milk production and body condition score and assigned to either the control or the stair-step compensatory nutrition (SSCN) regimen 16 weeks prior to expected calving date. Control cows were fed according to National Research Council [National Research Council., 2001. Nutrient Requirements of Dairy Cattle. 7th rev. ed. Natl. Acad. Sci., Washington, DC.] recommendations and for ad libitum intake during late lactation and the far-off dry period. The SSCN cows were subjected to dietary energy restriction [80% of net energy for lactation requirements (NE_L)] during late lactation in order to maintain body weight, followed by realimentation (130% of NE_L) during the far-off dry period to induce a compensatory response. A common diet was fed thereafter. The SSCN cows gained less body condition during late lactation and tended to gain more body condition during the far-off dry and transition periods than control cows. There was no difference in dry matter intake during the prepartum transition period and early lactation. Milk yield was not affected by treatment. Serum nonesterified fatty acids (NEFA) were not altered by dietary treatment during late lactation and the dry period; however NEFA were lower in SSCN cows at week 4 of the subsequent lactation. Serum insulin was higher in SSCN cows 8 weeks prior to parturition (end of restriction), tended to be higher at 4 weeks (end of realimentation) before calving, and was also higher at week 12 of early lactation. An SSCN regimen stimulated body condition gain of mature dairy cows during the dry period, did not affect periparturient nutrient metabolism, and led to modest improvements in metabolic parameters later in the subsequent lactation.     

Mastitis detection in dairy cows by application of fuzzy logic

The aim of the present research was to develop a fuzzy logic model for classification and control of mastitis for cows milked in an automatic milking system. Recording of data was performed on the University of Kiel's experimental dairy farm “Karkendamm”. A data set of 403,537 milkings from 478 cows was used. Mastitis was determined according to three different definitions: udder treatments (1), udder treatment or somatic cell counts (SCC) over 100,000/ml (2) and udder treatment or SCC over 400,000/ml (3). Mastitis alerts were generated by a fuzzy logic model using electrical conductivity, milk production rate and milk flow rate as input data. To develop and verify the model, the data set was randomly divided into training data (284,669 milkings from 319 cows) and test data (135,414 milkings from 159 cows). The evaluation of the model was carried out according to sensitivity, specificity and error rate. If the block-sensitivity was set to be at least 80%, the specificities ranged between 93.9% and 75.8% and the error rate varied between 95.5% and 41.9% depending on mastitis definition. Additionally, the average number of true positive cows per day ranged from 0.1 to 7.2, and the average number of false negative positive cows per day ranged from 2.4 to 5.2 in an average herd size for the test data of 39.7 cows/day. The results of the test data verified those of the training data, indicating that the model could be generalized.

Fuzzy logic is a useful tool to develop a detection model for mastitis. A noticeable decrease in the error rate can be made possible by means of more informative parameters.     

Serum constituents analyses in dairy cows: effects of duration and temperature of the storage of clotted blood

We studied the effects of storage time and temperature of clotted whole blood on the amounts of 17 analytes in bovine blood serum. Serum separated after blood was allowed to stand for 2, 4, 6, 12 and 24h at room temperature or on ice. Results obtained for phosphorous, magnesium, urea, cholesterol, beta-hydroxybutyrate (BHBA), triglyceride, albumin, total protein and gamma-glutamyletransferase (GGT) were not influenced by storage at room temperature or on ice for as long as 24h. Duration of the clotted whole blood storage had a significant effect on calcium, glucose concentrations, creatine kinase (CK) and aspartate aminotransferase (AST) activities and temperature had a significant effect on glucose, non-esterified fatty acids, CK and bilirubin concentrations.     

引发奶牛乏情的疾病研究进展

奶牛乏情是指产后60～90 d没有发情表现的经产奶牛及14～18个月龄不发情的育成牛,机体不表现出任何明显的发情状态,导致卵泡发育不良,从而影响机体排卵,引起发情周期紊乱、妊娠推迟,这对奶牛业的发展产生重大的影响。本文主要综述奶牛出现乏情状态的繁殖性疾病的研究状况,为进一步研究奶牛产后乏情提供理论依据。     

Influence of low phosphorus intake during early lactation on apparent digestibility of phosphorus and bone metabolism in dairy cows

In this study, the effects of reducing the dietary phosphorus (P) supply during the first 4 months of lactation on P balance and bone metabolism were investigated in dairy cows during a full lactation, including the dry period. Twenty-two multiparous cows of the Swedish Red and White Breed were included in the experiment. Eleven cows received a dietary P concentration of 0.43% of DM during the whole lactation (NP), and 11 cows received a dietary P concentration of 0.32% of DM during the first 4 months of lactation, followed by 0.43% of DM during the rest of lactation (LP). Total collection of faeces was carried out during five different stages of lactation, for 5 consecutive days at each occasion. The dynamics of bone metabolism was investigated by monitoring one bone-formation marker, identifying osteocalcin (OC), and one bone-resorption marker identifying C-telopeptide fragments of collagen type I (CTx) in blood plasma. At the two first collection periods, 3–7 and 11–15 weeks after parturition, the apparent digestibility of P was higher in the LP cows (52%) than in the NP cows (42%). During the following collection periods, no difference in the apparent digestibility could be noted between the two groups of cows. Phosphorus retention did not differ between treatments at any collection period. The highest retention was observed during late lactation and during the dry period. The profiles of the bone metabolism markers indicated a net resorption of bone during early lactation, but there were no differences in marker concentrations between the groups during early lactation, indicating that the LP diet did not induce a further elevated net bone resorption.     

Ingestion of medium chain fatty acids by lactating dairy cows increases concentrations of plasma ghrelin

The purpose of this study was to elucidate the effects of medium-chain fatty acids (MCFAs) on plasma ghrelin concentration in lactating dairy cows. Five early-lactating Holstein cows were randomly assigned to 2 dietary treatments in a crossover design with 2-wk periods. Treatments consisted of diets supplemented or not (control) with calcium salts of MCFAs (MCFA-Ca; 1.5% dry matter). Plasma hormone and metabolite concentrations in blood samples taken from the jugular vein were measured on the morning of feeding on day 14 of each period. Dry matter intake, milk protein, and lactose content of cows fed the MCFA-Ca diet were decreased compared with controls, but with no change in milk yield. Plasma ghrelin concentrations were higher in cows fed the MCFA-Ca diet; however, no significant effect was found on glucagon-like peptide-1 concentrations in plasma. Plasma insulin concentrations decreased, but plasma glucagon concentrations remained unchanged in cows fed the MCFA-Ca diet. The concentrations of nonesterified FAs, total cholesterol, and β-hydroxybutyrate in plasma increased in these cows. In conclusion, dietary MCFAs increase the plasma ghrelin concentrations in lactating dairy cows.     

植物甾醇对泌乳前期奶牛生产性能及血浆生化指标的影响

本试验旨在研究添加不同剂量植物甾醇对泌乳前期荷斯坦奶牛生产性能及血浆生化指标的影响。选用泌乳期相近的健康荷斯坦奶牛24头,随机分成4组,每组6头,Ⅰ组为空白对照组,饲喂基础日粮,Ⅱ、Ⅲ、Ⅳ组分别在基础日粮中添加200、400和800 mg/d植物甾醇,研究不同添加量的植物甾醇对奶牛生产性能及血液生化指标的影响。结果表明：①各试验组血浆生化指标Ⅱ组变化最为明显。较Ⅰ组而言,Ⅱ组血浆雌激素、孕酮、催乳素、卵泡刺激素、黄体生成素、干扰素、白细胞介素2、高密度脂蛋白胆固醇均显著提高（P＜0.05）,丙二醛含量显著下降（P＜0.05）。②较Ⅰ组而言,Ⅲ组血浆白细胞介素2、高密度脂蛋白胆固醇均显著提高（P＜0.05）。③与Ⅰ组相比,Ⅳ组血浆甘油三酯含量明显下降（P＜0.05）,总超氧化物歧化酶显著提高（P＜0.05）。添加植物甾醇可提高奶牛的泌乳量,改善奶牛内源激素不平衡的状况,并促进奶牛发情,改善奶牛脂类代谢情况,改善奶牛体质,其中200 mg/d植物甾醇添加量为最适添加量。     

The effects of providing shade to lactating dairy cows in a temperate climate

In a two-period replicated crossover design, four groups of lactating Holstein Friesian dairy cows (n = 10 per group) were kept on pasture to investigate the effects of providing artificial shade in summer on their vaginal temperature, behaviour and milk production. Two groups had access to shade and two groups in adjacent paddocks had no shade for a 10-day period before the treatments were switched. The body temperature rhythm was recorded in all animals using vaginal data loggers. Daily milk yield and milk composition was measured for each cow. Standing without grazing, lying and grazing behaviour was recorded continuously by observers for two 24-h periods during each 10-day treatment period. Shade use was recorded daily from 0800 to 2000 h. The provision of shade reduced (P < 0.05) mean vaginal temperature. This was particularly evident between 1000 and 1500 h, when the increase in vaginal temperature was significantly (P < 0.001) lower in shaded cows compared to cows without shade. No effect of shade (P > 0.05) on the maximum and minimum vaginal temperature, or the amplitude of the vaginal temperature rhythm was found. Cows with access to shade preferred (P < 0.001) using it mainly during the mid-afternoon, while, in contrast, cows with no shade grazed more (P < 0.001) at this time. The total time spent grazing, standing without grazing and lying per 24 h did not differ (P > 0.05) between treatments. Milk production was higher (P < 0.05) in cows that had access to shade compared to those without, but milk composition was not affected (P > 0.05) by shade treatment. These data suggest that the provision of shade is an effective method to reduce heat load in dairy cows under New Zealand summer conditions and, in addition, may increase daily milk yield. Despite only mild summer conditions, vaginal temperature was elevated during the mid-afternoon in non-shaded cows but did not cause a significant disruption in the underlying circadian body temperature rhythm compared to shaded cows.     

Development of a model for the prediction of feed intake by dairy cows: 1. Prediction of feed intake

A study was undertaken to develop a model for the prediction of dry matter intake by lactating Holstein Friesian dairy cows. To estimate the model parameters, a calibration dataset was compiled with the data from 32 feeding experiments conducted at 9 different sites. The database contained weekly information on 1507 lactating Holstein Friesian dairy cows regarding their diet composition and feed analysis, together with their individual voluntary feed intake, milk yield (MY), milk composition, parity, days in lactation and days pregnant.Dry matter intake was predicted from feed and animal characteristics. The feed chemical composition and digestibility can be related to feed degradation, bulk volume, intake rate, palatability and other factors influencing feed intake. Therefore, the data of standard feed analysis were used to estimate the satiety value of numerous commonly used feeds and forages. The satiety value is the measure of the extent to which a feed limits intake. The cows' ability to process the intake-limiting satiety value-units is expressed as the feed intake capacity, which is predicted from parity, days in milk and days of pregnancy which are indicators of the size and physiological state of the cow. This study shows that feed intake can be predicted using a limited number of easy-to-measure inputs that are available on commercial farms, yet reasonably biologically sound. Because the model inputs are not related to animal output (milk yield or body weight), future extension of the intake model with models for the prediction of animal performance is possible.     

Interrelationship of growth hormone AluI polymorphism and hyperketonemia with plasma hormones and metabolites in the beginning of lactation in dairy cows

A polymorphic site of the growth hormone gene (AluI polymorphism) that results in an amino acid change at position 127 of the protein chain (leucine, L to valine, V) has been linked to differences in circulating metabolites and metabolic hormones of calves and bulls and to milk yield traits of lactating cows. Our objective was to investigate the interrelationship of this polymorphism with plasma concentrations of β-hydroxybutyrate, insulin, IGF-I and leptin in postpartum dairy cows. Blood samples were taken from clinically healthy, spring-calving, group-fed Holstein-Friesian cows (n = 257; 7 large-scale farms) 4–13 days after calving. Of all herds, 100 cows had plasma β-hydroxybutyrate levels above 1.2 mmol/l and 157 cows were normoketonemic. The proportion of valine carriers and LL cows was not different within groups of normo- and hyperketonemic animals. Genotype was not associated with plasma β-hydroxybutyrate, insulin, IGF-I and leptin levels either in all of the herds or in the two with the highest proportion of the valine allele carriers (n = 28, 72%). We found significantly lower insulin, IGF-I and leptin concentrations in the presence of hyperketonemia compared to normoketonemic cows. There were strong negative correlations between BHB and the other blood parameters, while insulin, IGF-I and leptin were positively related to each other. In conclusion, in the first two weeks after calving we could not demonstrate any effect of AluI polymorphism on plasma concentrations of β-hydroxybutyrate and metabolic hormones studied. Hyperketonemia was associated with a significant decrease in insulin, IGF-I and leptin blood levels. We infer that cows homozygous for the leucine allele or carrying the valine allele may have a similar endocrine and metabolic response to the challenge of increased nutrient demand early postpartum and that the presence of hyperketonemia is mainly linked to the hormonal and metabolic changes occurring at the onset of lactation.     

Rumen microbiota succession throughout the perinatal period and its association with postpartum production traits in dairy cows:A review

The transition period for dairy cows usually refers to the 3 weeks pre-calving to the 3 weeks post-calving.During this period,dairy cows undergo metabolic and physiological adaptations because of their sus-ceptibility to metabolic and infectious diseases.Poor feeding management under these circumstances may adversely affect the health and subsequent production performance of the cows.Owing to long-term adaptation and evolution,the rumen has become a unique ecosystem inhabited by a complex microbial community closely associated with its natural host.Dietary components are metabolized by the rumen microbiota,and volatile fatty acids and microbial protein products can be used as precursor substances for synthesizing meat and milk components.The successful transition of perinatal dairy cows includes changes in diet,physiology,and the rumen microbiota.Rumen microbial profiles have been confirmed to be heritable and repairable;however,adverse circumstances affect rumen microbial composition,host digestion and metabolism,as well as postpartum production traits of dairy cows for a certain period.Preliminary evidence indicates a close relationship between the rumen microbiota and animal performance.Therefore,changes in rumen microbes during the transition period and the intrinsic links between the microbiota and host postpartum phenotypic traits need to be better understood to optimize production performance in ruminants.     

Hoof disorders, locomotion ability and lying times of cubicle-housed compared to pasture-based dairy cows

Forty six spring-calving Holstein–Friesians (12 primiparous, 34 pluriparous) were block-paired (expected calving date, parity, body condition score and genetic merit) and allocated to either a PASTURE or HOUSED system for a full production cycle (− 40 to 305 days relative to calving). Both hind claws were inspected on six occasions (− 40, 10, 35, 85, 120 and 210 days relative to calving) to determine the severity of 5 disorders (sole and white line area haemorrhages, white line disease, heel horn erosion, digital dermatitis and other lesions). Six aspects of locomotion ability (tracking, spine curvature, speed, head bobbing, general symmetry and abduction/adduction) were assessed from 1 (normal) to 5 (abnormal) every 2 weeks. Throughout the study records of clinical lameness were kept for all animals. Lying times of 26 block-paired cows (PASTURE n = 13, HOUSED n = 13) were recorded automatically every 5 min for 48 h at 33, 83 and 193 days post-calving. Data were analysed using mixed models for repeated measures, logistic regression and survival analysis, as appropriate. The severity of hoof disorders was lower for PASTURE compared to HOUSED cows from 85 days post-calving onwards (P < 0.05). HOUSED cows had a greater hazard ratio (P < 0.01) of presenting an abnormal (i.e. scoring ≥ 3) tracking (2.8), spine curvature (2.3), head bobbing (3.6), general symmetry (3.0), abduction/adduction (4.2) and for the average (3.9) of all locomotion aspects investigated (i.e. abnormal locomotion). Furthermore, HOUSED cows had a greater odds ratio (6.5, P < 0.01) of clinical lameness from day 180 post-calving onwards. Mean total lying times per 48 h period were shorter (P < 0.001) for HOUSED compared to PASTURE cows (18.1 h, SE 0.71 vs. 20.5 h, SE 0.73). In summary, from day 85 post-calving to the end of the production cycle PASTURE cows had less severe hoof disorders, better locomotion ability and reduced likelihood of clinical lameness compared to similar cows in a HOUSED system. The PASTURE system also facilitated longer, undisrupted lying times that have beneficial implications for lameness. A PASTURE system therefore improved cow welfare in terms of lameness compared to a HOUSED system.     

Variation in selected blood plasma constituents during the post-partum and breeding periods in dairy cows

Concentrations of insulin-like growth factor-I, albumin, beta hydroxybutyrate, glucose and urea were measured in 12 plasma samples collected over 9 weeks from mid-August from each of 40 cows in four seasonal herds which calved from mid-July. These herds comprised Jersey or Holstein-Friesian animals, with each breed grazed at two stocking rates. Daily dry matter intakes (kg dry matter/cow/day), which were estimated from pasture assessments before and after grazing, ranged from 4% (low stocked Jersey herd) to 38% (high stocked Friesian herd) below recommended intakes for each breed of cow in peak lactatipn. Stocking rate was associated with a 4% reduction in liveweight for cows in the high stocked herds and a 20% reduction in daily milk production (as a proportion of the low stocked herds' liveweight and milk production).

Eight cows produced at least one blood sample with a beta hydroxybutyrate concentration of more than 1.0 mmol/l. There were 42% of samples with glucose concentrations greater than 4.1 mmol/l. These two concentrations were the maximum values classified as normal for these two metabolites by the Ruakura Animal Health Laboratory. No concentrations of the other metabolites were outside their respective normal ranges. Breed, age and individual animals usually had greater effects on the average metabolite concentrations than did stocking rate.

The greatest effect was associated with sample day, especially for insulin-like growth factor-I and urea. A significant breed x stocking rate x sample day interaction in urea concentrations indicated that changes in the feeding value of the grazed pastures available to each herd were sufficient to produce separate fluctuating patterns in the daily average concentrations.

These results showed that frequent sampling on a herd basis would be necessary to identify the significance of factors which may be contributing to sample day variation in the concentration of metabolites in the plasma of pasture-fed cows.     

Effect of various iodine supplementations, rapeseed meal application and two different iodine species on the iodine status and iodine excretion of dairy cows

The aim of the present study was to investigate the impact of various feed iodine supplementations up to the permitted maximum level in the EU, the effect of applying rapeseed meal (RSM) compared to a glucosinolate (GSL) free ration and the impact of two different iodine species (iodide, iodate) on milk, urinary, faecal and blood serum iodine as well as on T₃ and T₄ levels of blood. The results of the milk iodine are not completely shown but partly discussed in this paper. The study was conducted with 32 dairy cows, divided into 4 groups with 8 animals each. In two groups the cows were fed distillers dried grains with solubles (DDGS) as main protein source (16.5% of ration DM), in the other groups rapeseed meal (3.5 mmol GSL/kg) was applied. In each case half of the animals received feed with iodine in the form of potassium iodide, the other half as calcium iodate. Iodine supplementations of 0, 0.5, 1, 2, 3, 4 and 5 mg/kg DM were tested in consecutive periods of 21 days each. The supplementary iodine increased iodine contents of serum, urine and faeces. RSM application resulted in consistently higher iodine contents in the mentioned matrices just displaying significant differences at high supplementation levels. When feeding DDGS, at high iodine supplementations iodide caused higher serum and faecal iodine than iodate. Besides, the iodine species showed no consistent impact on the tested parameters. At the highest tested iodine supplementation (5 mg/kg DM) in the experimental groups (DDGS/iodide, DDGS/iodate, RSM/iodide, RSM/iodate) the iodine concentration of serum amounted to 234, 157, 334 and 361 µg/l, of urine to 1134, 1020, 2341 and 2513 µg/l and of faeces to 673, 354, 715 and 790 µg/kg fresh matter. At the same supplementation level T₄ was significantly lowered. No impact was shown for the RSM application and the iodine species on T₃ and T₄. The results of the present study indicate that high iodine intakes not only cause strong increases in milk and urinary iodine but also lead to a considerable rise of iodine excretion via faeces. RSM in feed causes a shift of iodine normally excreted via milk to an excretion via urine and faeces accompanied by higher serum iodine.     

Effects of selenium yeast on rumen fermentation, lactation performance and feed digestibilities in lactating dairy cows

The objective was to evaluate the effects of selenium-yeast (SY) supplementation on rumen fermentation, lactation performance and feed digestibilities in dairy cows. Twenty-eight multiparous (2.5 ± 0.3 parity) Holstein dairy cows, averaging 625 ± 18.2 kg of BW, 63 ± 3.0 days in milk and average daily milk production of 26.2 ± 0.5 kg/cow were used in a replicated 4 × 4 Latin square experiment. Treatments were: control, LSY, MSY and HSY with 0, 150, 300 and 450 mg selenium yeast (Sel-Plex®, 1 g/kg selenium, produced from Saccharomyces cerevisiae CNCM I-3060) per kg of diet dry matter (DM), respectively. Experimental periods were 45 days with 30 days of adaptation and 15 days of sampling. Ruminal pH was lower for MSY than for control and was linearly (P = 0.03) decreased, whereas total VFA concentration was linearly and quadratically (P ≤ 0.01) increased with increasing SY supplementation, with the least for control, followed by LSY and HSY, and the highest for MSY. Ratio of acetate to propionate was lower for LSY, MSY and HSY than for control, and was linearly and quadratically (P ≤ 0.01) decreased as SY supplementation increased due to an increase in molar proportion of propionate. Ruminal ammonia N content was lower (P ≤ 0.01) for MSY and HSY than for control and was linearly decreased (P ≤ 0.01) with increasing SY supplementation. Dry matter intake, proportions and yields of milk fat, protein and lactose were not affected (P > 0.05). Milk yields and 4% FCM were higher (P ≤ 0.05) for LSY and MSY than for HSY and control. Milk selenium content was linearly and quadratically (P ≤ 0.01) increased as increasing SY supplementation, with the least for control, followed by LSY and MSY, and the highest for HSY. Digestibilities of DM, organic matter (OM), crude protein (CP), ether extract (EE), aNDF and ADF in the total tract were higher (P < 0.01) for LSY and MSY than for control and HSY. The results indicate that supplementation of diet with SY improved rumen fermentation, milk yields, milk selenium, and feed digestion. It was suggested that the SY stimulated the digestive microorganisms or enzymes in a dose-dependent manner. In the experimental conditions of this trial, the optimum selenium-yeast dose was about 300 mg per kg diet DM.     

Influence of a marine algae supplementation on the oxidative status of plasma in dairy cows during the periparturient period

This study was part of a larger study that addressed the effects of marine algae (ALG) supplementation in the ration of high yielding periparturient dairy cows. The objectives were to induce milk fat depression (MFD) in early lactation by feeding docosahexaenoic acid (DHA) from ALG and to determine the effects on milk production, milk components and metabolic status early post partum. This study focuses on the oxidative status in the plasma during the ALG supplementation. Plasma samples were collected from 16 Holstein Friesian cows at the day of parturition and at −1, 2, 4 and 6 weeks relative to calving with half of the cows receiving the ALG supplement (44 g DHA/d) from 3 weeks pre partum on. The following parameters were measured in plasma: ferric reducing ability of plasma (FRAP), α-tocopherol level, glutathione peroxidase activity (GSH-Px) and thiobarbituric acid reactive substances (TBARS) concentration. There was a significant effect of time for FRAP and α-tocopherol indicating changes in the plasma oxidative status around parturition. The ALG supplementation was successful in creating a milk fat depression (MFD) but could not improve the energy balance. Feeding of ALG significantly increased lipid peroxidation as measured by TBARS, probably through their high content of n-3 polyunsaturated fatty acids.     

Intravaginal administration of lactic acid bacteria modulated the incidence of purulent vaginal discharges,plasma haptoglobin concentrations,and milk production in dairy cows

This investigation studied the effects of intravaginal administration of a mixture of lactic acid bacteria (LAB) on the incidence of purulent vaginal discharges (PVD), plasma haptoglobin concentrations, and milk production in dairy cows. A total of 82 pregnant primiparous and multiparous Holstein dairy cows were used in this study. Half of the cows received intravaginally 1 mL of LAB at 10¹⁰–10¹² cfu/mL and the other half 1 mL of reconstituted skim milk (i.e., carrier) (controls). Administration of LAB was conducted once per wk during 2 and 1 wk before the expected day of calving and at 1, 2, 3, and 4 wk postpartum. Data demonstrated that intravaginal administration of LAB decreased the occurrence of PVD at 3 wk postpartum (P < 0.05). Concentrations of plasma haptoglobin, an acute phase protein often associated with uterine infections, was lower in cows treated with the LAB mixture at 2 wk (P < 0.001) and 3 wk (P < 0.05) postpartum. Treatment with LAB did not improve overall pregnancy rate, but the treated multiparous cows produced more milk than their control counterparts (P < 0.05), whereas no difference was observed in primiparous cows regarding milk yield (P > 0.05). Overall, this is the first study demonstrating that intravaginal LAB administration lowers the incidence of PVD and enhances milk production in dairy cows. Further research is warranted to evaluate the effects of LAB on reproductive performance in a larger cohort of cows.     

Changes in feed intake,nutrient digestion,plasma metabolites,and oxidative stress parameters in dairy cows with subacute ruminal acidosis and its regulation with pelleted beet pulp

The objectives of this study were to 1) determine the variation of nutrient digestion, plasma metabolites and oxidative stress parameters triggered by induced subacute ruminal acidosis(SARA); and 2) evaluate the ability of pelleted beet pulp(BP) as a replacement for ground corn to alleviate SARA. Eight Holstein-Friesian cows were fed four diets during four successive17-day periods: 1) total mixed ration(TMR) containing 0% finely ground wheat(FGW)(W0); 2) TMR containing 10% FGW(W10); 3) TMR containing 20% FGW(W20); and 4) TMR containing 10% BP as a replacement for 10% ground corn(BP10). The SARA induction protocol reduced the mean ruminal pH from6.37 to 5.94, and the minimum ruminal pH decreased from 5.99 to 5.41 from baseline to challenge period. Mean ruminal pH increased from 5.94 to 6.05, and minimum daily ruminal pH increased from 5.41 to 5.63, when BP was substituted for corn. The apparent digestibility of nutrients was not affected by the dietary treatments, except that the digestibility of neutral detergent fibre(NDF) and acid detergent fibre(ADF) was reduced in cows fed the W20diet compared with cows fed the W0 and W10 diets, and cows fed the BP10 diet had higher NDF and ADF digestibility than the cows fed the W20 diet. Cows fed the W20 diet had a lower plasma concentration ofβ-hydroxybutyrate(BHBA), non-esterified fatty acids(NEFA), cholesterol, triglyceride, and total antioxidative capacity(TAC), and a higher plasma concentration of glucose, insulin, malonaldehyde(MDA), super oxygen dehydrogenises(SOD), and glutathione peroxidase(GSH-Px) than cows fed the W0 diet. Substitution of BP for corn increased concentrations of plasma BHBA and TAC, but decreased concentrations of plasma MDA. Our results indicate that reduction of fibre digestion; the concomitant increase of plasma glucose and insulin; the decrease of plasma BHBA, NEFA, cholesterol, and triglyceride; and changes of plasma oxidative stress parameters are highly related to SARA induced by W20 diets. These variables may be alternative candidates for SARA diagnosis. We also suggest that the substitution of BP for corn could reduce the risk of SARA, increase fibre digestion, and improve the antioxidant status in dairy cows.     

仙人掌果实对奶牛泌乳性能、氮利用及采食行为的影响

本研究评估了仙人掌果实与不同粗饲料结合对荷斯坦奶牛采食量、营养物质消化率、氮平衡、摄食行为和泌乳性能的影响。试验选择泌乳期为(72±11)d的8头奶牛,采用4×4拉丁试验设计,共4种试验日粮:T1组为75%青贮高粱组,T2组为75%象草组,T3组为37.5%青贮高粱+37.5%仙人掌果实,T4组为37.5%象草+37.5%仙人掌果实。结果:青贮高粱组干物质摄入量最高(P<0.05)。不同日粮组干物质、粗蛋白质、粗脂肪、非纤维碳水化合物和总可消化养分摄入量存在显著差异(P<0.05)。仙人掌果实组较青贮高粱和象草组日饮水量降低44.52%(P<0.05)。与象草组、象草+仙人掌果实组相比,青贮高粱组、青贮高粱+仙人掌果实组氮平衡降低59.71%和27.49%(P<0.05)。结论:奶牛日粮中以仙人掌果实与青贮高粱或象草的组合并没有改变荷斯坦奶牛的产奶量,但降低了营养物质和水分摄入量,同时提高了养分消化率。