Correlation of Whole Blood Concentrations of Acetoacetate, β-Hydroxybutyrate,Glucose and Milk Yield in Dairy Cows as Studied Under Field Conditions

The whole blood concentrations of acetoacetate (AA concn), β-hydroxybutyrate (BHB concn) and glucose (gluc concn) of 662 Ayrshire and Friesian dairy cows were measured and their milk yield during the indoor-housing period was recorded. Simple correlations among these parameters were evaluated. The correlation between the AA concn and the BHB concn (r = 0.869) was statistically highly significant (P < 0.001), as were the correlations of the logarithmic value of the AA concn with the gluc concn (r = —0.471) and with the milk yield (r = 0.259), and the correlation between the BHB concn and the glue concn (r = —0.288). The milk yield was found also to be associated with the BHB concn and the glue concn (P< 0.001). The associations between each pair of blood parameters were highly significant, too (P < 0.001). The AA concn was taken to be at least as good an indicator of the energy status of dairy cows as the BHB concn and the gluc concn. The AA concn is not diet-derived like the BHB concn and not as stress-sensitive as the blood concentration of free fatty acids and its diurnal variation is not as wide as the BHB concn and the gluc concn in subclinically ketotic cows. Thus the AA concn may be used as a proxy of the energy status and the ketotic stage of dairy cows under field conditions.Key words: acetoacetate, ß-hydroxy butyrate, glucose, energy status, dairy cattle     

Induction of Parturition in the Cow using Cloprostenol and Dexamethasone in Combination

Two experiments were designed to test the hypothesis that induction of parturition in the cow would be more predictable with the simultaneous use of a combination of cloprostenol and dexamethasone than with either hormone used alone.

In experiment I all 19 beef cows treated with 500 μg cloprostenol and 25 mg dexamethasone in combination calved within 72 hours whereas dexamethasone (n = 19) or cloprostenol (n = 16) treatments alone each resulted in two induction failures. In those cows successfully induced, the mean interval from treatment to birth was 34.6 ± 1.4 hours for the cloprostenol plus dexamethasone group, 43.3 ± 2.4 hours for the dexamethasone group and 44.9 ± 2.1 hours for the cloprostenol group. Control cows (n = 15) did not calve during the first 72 hours after treatment with saline. The incidence of retained placenta ranged from 19 to 53% in induced groups whereas placentae were not retained by cows in the control group.

In experiment II all 30 beef cows in the cloprostenol plus dexamethasone group calved within the 72 hour limit, with a mean interval of 39.1 ± 1.0 hours. Twenty-six of 31 cows calved within 72 hours with a mean interval of 51.9 ± 3.4 hours after a single injection of cloprostenol and 29 of 33 cows calved within 72 hours with a mean interval of 52.6 ± 3.3 hours after two injections of cloprostenol, 12 hours apart. Five of 34 control cows calved within 72 hours of time of treatment. The incidence of retained placenta was again high in induced cows. Results indicate that the simultaneous administration of cloprostenol and dexamethasone does constitute a safe, reliable and effective method of inducing parturition in the cow.

     

Treatment of anovulatory anoestrous postpartum dairy cows with a gonadotropin-releasing hormone (GnRH), prostaglandin F2𝛂, GnRH regimen or with progesterone and oestradiol benzoate

AIM: To compare 2 treatments for anovulatory anoestrus (AA) in postpartum dairy cows. The treatments were combinations of gonadotropin-releasing hormone (GnRH) and prostaglandin F_2𝛂 (PG) or progesterone (P4) and oestradiol benzoate (ODB).

METHODS: Forty AA cows from each of 5 herds were blocked by age (2 or >2 years old) and randomly assigned to 1 of 2 treatments. The first group (GPG) were treated with 250 𝛍g of a GnRH analogue, gonadorelin, followed 7 days later by 15 mg of the PG analogue, luprostiol. Two days later the cows were injected with 250 𝛍g of gonadorelin. Cows were artificially inseminated 16–24 h after the second GnRH injection. The second group (P4+ODB) were treated with an intravaginal P4 releasing device for 6 days, followed 24 h after device removal by injection of 1 mg of ODB. Cows were pregnancy tested 35–40 days after the initial insemination and twice again at 6–8 week intervals thereafter.

RESULTS: There was no significant difference between P4+ODB and GPG groups in the percentage of cows submitted for insemination in the first 7 days (94.0% vs 100% for P4+ODB vs GPG, respectively; p>0.3), in conception rate to first insemination within the first 7 days (43.6% vs 35.0% for P4+ODB vs GPG, respectively; p>0.2), in the percentage of cows conceiving in the first 28 days of the breeding period (68.0% vs 58.3%, P4+ODB vs GPG, respectively; p>0.1), or in median interval from the end of treatment to conception (20 vs 21days;p>0.1).

CONCLUSIONS: No differences in the reproductive performance of AA cows treated with either P4+ODB or GPG were detected. However, given the small number of animals enrolled, further data are required before the GPG protocol can be recommended for treatment of AA cows.     

Metabolic parameters and their relationship to energy balance in multiparous Simmental,Brown Swiss and Holstein cows in the periparturient period as influenced by energy supply pre‐ and post‐calving

A study was conducted to evaluate the effects of three energy supply (E) levels [low (L), medium (M), high (H)], both pre‐partum (PRE) and post‐partum (POST), and their interactions on metabolic parameters and energy balance (EB) in dairy cows of three breeds. In both phases, E levels applied to a total of 81 multiparous cows of breeds Simmental (SI), Brown Swiss (BS) and Holstein–Friesian (HF; n = 27 for each breed) were 75%, 100% and 125% of recommendations of the German Society of Nutrition Physiology, using a 3 × 3 factorial arrangement of treatments. During the pre‐calving period, serum concentrations of non‐esterified fatty acids (NEFA) were higher for L_PRE cows, and glucose concentrations were elevated for H_PRE cows. During the lactation period, NEFA concentrations were greatest for treatment L_POST. Mean concentrations of β‐hydroxybutyrate (BHB) were highest for cows of the L_POST treatment, intermediate for M_POST and lowest for H_POST. Glucose concentrations were lower for L_POST cows. SI cows had lower BHB concentrations both pre‐ and post‐calving and higher glucose concentrations during early lactation than the other breeds. BHB concentration POST was highest for BS cows. Restricted feeding PRE resulted in a better energy status of cows fed above energy requirements POST (E_PRE × E_POST interaction). HF cows had a higher EB pre‐calving, whereas SI cows had a less negative EB during early lactation, compared with the other breeds respectively. Correlations of serum NEFA, BHB and glucose concentrations with EB were strongest during the transition period. Results suggest that controlling energy intake during the dry period might be advantageous for the energy status of dairy cows after calving, whereas energy restriction in early lactation leads to metabolic stress. Evidence is provided of a clear relationship between EB and the blood metabolites NEFA and BHB, especially in the transition period.     

Use of test day milk fat and milk protein to detect subclinical ketosis in dairy cattle in Ontario.

Serum beta-hydroxybutyrate (BHB) levels were determined for 1333 dairy cows in various stages of lactation and parity on 93 dairy farms in Ontario. The data were collected in a cross-sectional manner, as part of the 1992 Ontario Dairy Monitoring and Analysis Program. The median serum BHB was 536 mumol/L for all cows, with a range of 0 to 5801 mumol/L. When subclinical ketosis was defined as a serum BHB level of 1200 mumol/L or higher, the prevalence of ketosis for cows in early lactation (< 65 days in milk (DIM)) was 14.1%. Prevalences for mid lactation (65-149 DIM), late lactation (> 149 DIM), and dry cows were 5.3%, 3.2%, and 1.6%, respectively. The mean serum BHB was significantly higher in the early group compared with each of the other 3 groups (P < 0.05). There was a trend of increasing prevalence with increasing parity across all stages of lactation. Only the difference between the parity-1 group and the parity-4 and greater group was statistically significant (P < 0.05). Both test-day fat percent and test-day protein percent were significantly associated with subclinical ketosis. However, test-day fat percent and test-day protein percent, used alone or in combination, were not useful screening tests for identifying cows with subclinical ketosis.     

Individual variability in physiological adaptation to metabolic stress during early lactation in dairy cows kept under equal conditions

This study was conducted to investigate individual metabolic and endocrine adaptation to lactation under conditions of identical housing and feeding conditions in high-yielding dairy cows. Forty-five cows were studied on a research farm under standardized but practical conditions. From wk 2 before calving until wk 14 postpartum, blood samples were collected at weekly intervals and assayed for blood chemistry and various metabolites and hormones. Body weight, BCS, and backfat thickness were also recorded weekly. Milk yield, milk composition, and feed intake and energy balance were accordingly measured during the postpartum phase. The animals were retrospectively classified according to their plasma concentration of beta-hydroxybutyrate (BHB): cows in which a BHB threshold of 1 mM was exceeded at least once during the experiment were classified as BHB positive (BHB+); cows with BHB values consistently below this threshold were classified as BHB negative (BHB -). Using this classification, differences for NEFA and glucose concentrations were observed, but the mean calculated energy balance did not differ between the groups during the experimental period (-22.2 MJ of NE(1)/d +/- 4.7 for BHB+ and -18.9 MJ of NE(1)/d +/- 4.9 for BHB-). In BHB+ cows, the peripartum decrease (P < 0.05) of BW, BCS, and backfat thickness was more pronounced than in BHB- cows. Mean milk yields did not differ between groups. However, BHB+ cows had greater milk fat and lesser milk protein contents (P < 0.05), resulting in a greater (P < 0.05) fat:protein ratio than in BHB- cows. Thus, to some extent, cows were able to compensate for the negative energy balance by adjustments in performance. Milk acetone concentrations followed BHB concentrations in blood. Insulin-like growth factor-I and leptin concentrations were greater (P < 0.05) in BHB- cows during the time of observation than in the BHB+ cows. Comparing the reproductive variables recorded (first increase of progesterone, first service conception rate, number of services per conception, interval from calving to first AI, interval from first AI to conception, and days open) between the 2 groups yielded no significant differences. Our findings imply that despite comparable energy balance, there is considerable individual variation of the adaptive ability of cows during early lactation based on a variety of metabolic and endocrine variables.     

Relationship between herd size and annual prevalence of and primary antimicrobial treatments for common diseases on dairy operations in the United States

Dairy operations in states representing 86% of the United States’ national dairy herd were surveyed regarding the occurrence of common dairy diseases or disorders (digestive, respiratory, gastrointestinal, lameness, mastitis, navel infection) in specified production groups (weaned heifers, unweaned heifers, adult cows), and the most common antimicrobial preparation used to treat these conditions. Within disease and production group, disease frequency and characteristics of primary antimicrobial (drug class, availability, spectrum of activity, extra-label usage, withdrawal times) were compared among herd sizes (30–99, 100–499, and ≥500 cows) using chi-square or t-tests that accounted for the sampling design. The most common diseases were mastitis and lameness in cows, and gastrointestinal disease in unweaned calves, affecting 16, 11, and 15% of the target populations, respectively. Herd-level disease prevalence tended to increase as herd size increased, whereas within-herd prevalence tended to decrease as herd size increased. Broad-spectrum antimicrobials were selected as primary treatments by a majority of operations for nearly all diseases surveyed. When treating gastrointestinal disease, navel infection, or reproductive disorders, a majority of operations selected primary treatments not specifically labeled for that condition. Selection of over-the-counter preparations tended to decrease as herd size increased, whereas selection of broad-spectrum preparations tended to increase with herd size.     

Vitamin and mineral supplementation and rate of gain during the first trimester of gestation affect concentrations of amino acids in maternal serum and allantoic fluid of beef heifers

The objective of this study was to evaluate the effects of feeding vitamin and mineral (VTM) supplement and (or) rate of gain (GAIN) during early gestation on amino acid (AA) concentrations in allantoic fluid (ALF) and amniotic fluid (AMF) and maternal serum. Seventy-two crossbred Angus heifers (initial BW = 359.5 ± 7.1 kg) were randomly assigned to one of four treatments in a 2 × 2 factorial arrangement with main effects of VTM supplement (VTM or NoVTM) and rate of gain (GAIN; low gain [LG], 0.28 kg/d, vs. moderate gain [MG], 0.79 kg/d). The VTM treatment (113 g•heifer⁻¹•d⁻¹, provided macro and trace minerals and vitamins A, D, and E to meet 110% of the requirements specified by the NASEM in Nutrient requirements of beef cattle. Washington, DC: The National Academies Press. doi:10.17226/19014, 2016) was initiated 71 to 148 d before artificial insemination (AI). To complete the factorial arrangement of treatments, at breeding heifers were either maintained on the basal diet (LG), or received MG diet which was implemented by adding a protein/energy supplement to the LG diet. Thirty-five gestating heifers with female fetuses were ovariohysterectomized on d 83 of gestation and maternal serum, ALF, and AMF were collected. Samples were analyzed for concentrations of neutral AA: Ala, Asn, Cys, Gln, Gly, Ile, Leu, Met, Phe, Pro, Ser, Thr, Trp, Tyr, and Val; cationic AA: Arg, His, and Lys; and anionic AA: Asp and Glu. In serum, a VTM × GAIN interaction (P = 0.02) was observed for Glu, with greater concentrations for VTM-LG than VTM-MG. Concentrations of serum Cys, Met, and Trp were greater (P ≤ 0.03) for MG than LG. In ALF, concentrations of Glu were affected by a VTM × GAIN interaction, where VTM-MG was greater (P < 0.01) than all other treatments. Further, ALF from VTM had increased (P ≤ 0.05) concentrations of His, Asp, and 12 of the 14 neutral AA; whereas GAIN affected concentrations of Arg, Cys, and Asp, with greater concentrations (P ≤ 0.05) in MG heifers. In AMF, AA concentrations were not affected (P ≥ 0.10) by VTM, GAIN, or their interaction. In conclusion, increased concentrations of AA in maternal serum and ALF of beef heifers were observed at d 83 of gestation in response to VTM supplementation and rate of gain of 0.79 kg/d, which raises important questions regarding the mechanisms responsible for AA uptake and balance between the maternal circulation and fetal fluid compartments.     

Plasma progesterone, metabolic hormones and beta-hydroxybutyrate in Holstein-Friesian cows after superovulation

Metabolic hormones [insulin, leptin, insulin-like growth factor-I (IGF-I), thyroxine (T4) and triiodothyronine (T3)], progesterone (P4) and beta-hydroxybutyrate (BHB) serum concentrations were evaluated and their effect on the superovulation results of donor cows was investigated in a semi-arid environment. Body weight, body condition score (BCS) and lactation stage were also included in the analysis. Twenty-three Holstein-Friesian cows were superovulated with 600 IU FSHp following the routine procedure and flushed on day 7 in a Multiple Ovulation and Embryo Transfer Centre in the semi-arid area of Brazil. The corpora lutea (CL) were counted and blood samples were collected for assays. All of the hormones investigated and BHB serum concentrations were within the physiological ranges. There was a positive correlation between hormones, except between BHB and all the others. The leptin level was influenced by feeding status, as indicated by the BCS. Insulin, T4, T3 and BHB levels were affected by milking status. Dry cows had higher levels of all hormones except BHB. An optimum level of leptin resulted in the highest number of CL, while the linear increase of P4, T4 and IGF significantly increased the number of CL.     

Inflammatory and metabolic responses to an intramammary lipopolysaccharide challenge in early lactating cows supplemented with conjugated linoleic acid

Supplementation of dairy cows with trans‐10, cis‐12 conjugated linoleic acid (CLA) allows nutrient repartitioning despite an energy deficiency in early lactation, which might be a benefit for the immune system, too. In this study, we investigated potential nutrient sparing effects of CLA in early lactating cows with low plasma glucose concentrations exposed to an intramammary lipopolysaccharide (LPS) challenge. Fifteen multiparous Holstein cows were exposed to an intramammary LPS challenge in week 4 p.p. Eight cows (CLA) were supplemented daily with 70 g of lipid‐encapsulated CLA (6.8 g trans‐10, cis‐12 and 6.6 g of the cis‐9, trans‐11 CLA isomer; CLA) and seven cows with 56 g of control fat (CON). Blood samples were obtained every 30 min along with rectal temperature, heart and respiratory rate, and milk samples were taken hourly until 10 hr after the LPS application. Plasma was analysed for concentrations of glucose, free fatty acids, beta‐hydroxybutyrate (BHB), cortisol, insulin and glucagon. In milk, somatic cell count and activity of lactate dehydrogenase were determined. Initial plasma glucose concentration was lower in CLA than in CON. During the immunostimulation, CLA had higher glucose concentrations than CON, and BHB decreased distinctly in CLA, whereas CON cows maintained BHB concentration at a lower level. Body temperature in CLA increased earlier, the difference between peak and basal temperature was higher, and the decline thereafter occurred earlier. In conclusion, CLA supplementation of early lactating cows exposed to an intramammary LPS challenge affected local and systemic immune responses. We assume that CLA supplementation triggered glycogen storage. Cows supplemented with CLA provided more glucose and preferentially used BHB as an energy source during the immune response. The more intense metabolic and more concentrated endocrine responses support an immunomodulatory effect of CLA supplementation.     

Bovine Subclinical Ketosis in Dairy Herds in Iran

Subclinical ketosis (SCK) is defined as elevated concentrations of ketone bodies in the absence of clinical signs of ketosis. It is an important metabolic disease in dairy cattle during early lactation and is associated with losses in milk production and several other periparturient diseases. Limited information is available regarding the prevalence of SCK in dairy herds in Iran. The objectives of this study were (i) to determine the incidence of SCK in the dairy herds in Kerman province of Iran using serum beta-hydroxybutyrate (BHB) concentrations, and (ii) to investigate the relationship between serum concentrations of BHB and glucose of cows with SCK. In the present study, 90 multiparous Holstein cows (4-6 years old) from 11 commercial dairy herds were evaluated 3-4 weeks after calving. The distribution of blood BHB concentrations seemed to suggest a cut-off point of 1200 micromol/L between cows with and without SCK. At this cut-off point, 14.4% of tested cows (13/90) were classified as subclinically ketotic, with the prevalence rate within herd ranging from 10% to 20%. Cows with SCK were detected in all the investigated dairies except one. Blood glucose concentrations in cows with SCK were significantly lower (p < or = 0.05) than in cows without SCK, and serum BHB and glucose concentration were inversely correlated (r = -0.43, p < or = 0.05). The results suggest that, using a cut-off of 1200 micromol/L, BHB concentrations can be used during early lactation for diagnosis and to make management decisions for prevention and treatment.     

Prevalence of bovine ketosis in relation to number and stage of lactation

The prevalence of bovine ketosis as distributed among various selected subgroups of 504 Ayrshire and Friesian cows was studied during the indoor-housing season 1978–1979 in western and eastern parts of Finland. Special attention was paid to variation by lactation number. Also the differences in prevalence at various phases of lactation and at the end of pregnancy were investigated. The whole blood concentration of acetoacetate (AA concn) was analysed and used as a measure of subclinical and clinical bovine ketosis. AA cocns below 0.35 mmol/1, between 0.36 mmol/1 and 1.05 mmol/1 and over 1.05 mmol/1 were considered to indicate normal, subclinal and clinical ketotic stages, respectively. The prevalence of clinical ketosis in cows during 3 post-calving months was 13 %. The percentage of subclinical ketosis was 34. The prevalence of clinical ketosis was 3 %, 7 %, 20 %, 22 % and 13 % at the first, second, third, fourth and fifth, or sixth and later calving, respectively, and the frequency of subclinical ketosis 31 %, 41 %, 35 %, 32 % and 32 %, respectively. No case of ketosis was found in 54 cows at the end phase of pregnancy and only one during the first postcalving week. Only 2 cows (4 %) had the AA concn at a clinically ketotic level during the 65th—92nd postcalving days, 16 %, 17 % and 16 % during the 8th—21st, 22nd—42nd and 43rd—64th postcalving days, respectively.Key words: acetoacetate blood concentration, prevalence of bovine ketosis, lactation number, stage of lactation     

Diurnal variation and the effect of feed restriction on plasma and milk metabolites in TMR-fed dairy cows

The objective was to study the diurnal variation in metabolites in plasma and milk of dairy cows fed total mixed rations (TMR) with a low-energy (LE) or high-energy content (HE) expected to give a minor and a major diurnal variation, respectively. Further, the purpose was to quantify and compare the responses in plasma and milk parameters when cows changed from ad libitum to restrictive feeding. Eight multiparous, early-lactating Danish Holstein cows were used in a cross-over design with two consecutive 14-day periods. Blood and milk samples were collected hourly on day 11 of each period and on days 12-14 of each period, the cows were fed restrictively (65% of ad libitum dry-matter intake). The concentration of beta-hydroxybutyrate (BHB) in plasma was significantly higher in the evening for cows fed the HE TMR, than for cows fed the LE TMR. There was a significant diurnal variation in BHB in milk, with the highest concentrations between milkings and the lowest concentrations at milking. Non-esterified fatty acids (NEFA) in plasma showed significant diurnal variation that was caused by high concentrations in the morning. Plasma glucose did not show any diurnal variation. It has been argued that feeding a TMR removes diurnal changes related to feeding, which is contrary to earlier diurnal studies where concentrates have been fed twice daily. Feed restriction increased (P < 0.001) NEFA and BHB in plasma by 121 and 90%, respectively, while the glucose concentration decreased (P < 0.001) by 19%. Milk concentrations of BHB, citrate and fat increased (P < 0.001) by 163, 11 and 26%, respectively, because of feed restriction, while there were no changes in milk protein and lactose. The relatively high increase in BHB during feed restriction suggests that BHB is more advantageous as a milk indicator of metabolic status in dairy cows than citrate and fat.     

Relationship among blood indicators of lipomobilization and hepatic function during early lactation in high-yielding dairy cows

Blood indicators are used as a tool to diagnose metabolic disorders. The present work was conducted to study the relationships among blood indicators of lipomobilization and hepatic function in high-yielding dairy cows. Two groups of Holstein cows were studied: 27 early lactation cows and 14 mid lactation cows from four different herds with similar husbandry characteristics in Galicia, Spain. Blood samples were obtained to measure beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), triglycerides (TG), and the activity of aspartate transaminase (AST) and gamma-glutamyl transferase. Cows in early lactation had higher levels of BHB and NEFA than mid lactation cows. High lipomobilization (NEFA > 400 µmol/L) was detected in 67% and 7% of early lactation and mid lactation cows, respectively, while subclinical ketosis (BHB > 1.2 mmol/L) was detected in 41% and 28% of the early lactation and lactation cows, respectively. TG concentrations were low in all cows suffering subclinical ketosis and in 61% of the cows with high lipomobilization. During early lactation, 30% of cows suffered hepatic lipidosis as detected by levels of AST. Compromised hepatic function was observed in early lactation cows as shown by lower concentrations of glucose, total protein, and urea.     

Metabolic and endocrine profiles and reproductive parameters in dairy cows under grazing conditions: effect of polymorphisms in somatotropic axis genes

Background

The present study hypothesized that GH-AluI and IGF-I-SnabI polymorphisms do change the metabolic/endocrine profiles in Holstein cows during the transition period, which in turn are associated with productive and reproductive parameters.

Methods

Holstein cows (Farm 1, primiparous cows, n = 110, and Farm 2, multiparous cows, n = 76) under grazing conditions were selected and GH and IGF-I genotypes were determined. Blood samples for metabolic/endocrine determinations were taken during the transition period and early lactation in both farms. Data was analyzed by farm using a repeated measures analyses including GH and IGF-I genotypes, days and interactions as fixed effects, sire and cow as random effects and calving date as covariate.

Results and Discussion

Frequencies of GH and IGF-I alleles were L:0.84, V:0.16 and A:0.60, B:0.40, respectively. The GH genotype was not associated with productive or reproductive variables, but interaction with days affected FCM yield in multiparous (farm 2) cows (LL yielded more than LV cows) in early lactation. The GH genotype affected NEFA and IGF-I concentrations in farm 1 (LV had higher NEFA and lower IGF-I than LL cows) suggesting a better energy status of LL cows.There was no effect of IGF-I genotype on productive variables, but a trend was found for FCM in farm 2 (AB cows yielded more than AA cows). IGF-I genotype affected calving first service interval in farm 1, and the interaction with days tended to affect FCM yield (AB cows had a shorter interval and yielded more FCM than BB cows). IGF-I genotype affected BHB, NEFA, and insulin concentrations in farm 1: primiparous BB cows had lower NEFA and BHB and higher insulin concentrations. In farm 2, there was no effect of IGF-I genotype, but there was an interaction with days on IGF-I concentration, suggesting a greater uncoupling somatropic axis in AB and BB than AA cows, being in accordance with greater FCM yield in AB cows.

Conclusion

The GH and IGF-I genotypes had no substantial effect on productive parameters, although IGF-I genotype affected calving-first service interval in primiparous cows. Besides, these genotypes may modify the endocrine/metabolic profiles of the transition dairy cow under grazing conditions.     

丙二醇对围产期奶牛能量平衡及代谢产物的影响

为了研究丙二醇对围产期奶牛能量平衡、血液指标和肝脏甘油三酯与糖原含量的影响。选用24头体质量(683.1±14.9)kg、胎次(2.5±0.2)、上一泌乳期305d产奶量(7 339±18)kg和预产期(24.5±0.2)d的经产奶牛,随机分为4组,从分娩前19d开始分别在基础日粮中添加丙二醇0、150、300和450mL.d-1。结果表明:与对照组相比,添加丙二醇300和450mL.d-1,显著提高了奶牛分娩后7、21和35d体况评分,缓减了奶牛体质量下降程度,改善了奶牛分娩前14d和分娩后7、21和35d奶牛能量平衡(P<0.05)。300和450mL.d-1组奶牛分娩前14d和分娩后7、21和35d血糖和胰岛素浓度显著高于对照组(P<0.05)。300和450mL.d-1组奶牛分娩后7、21和35d血浆游离脂肪酸、β-羟丁酸和甘油三酯浓度显著低于对照组(P<0.05)。300和450mL.d-1组奶牛分娩后7、21和35d肝脏甘油三酯含量显著低于对照组(P<0.05),但分娩后7、21和35d肝脏糖原含量显著高于对照组(P<0.05)。结果提示在日粮中添加丙二醇能够减少肝脏脂肪沉积,加强葡萄糖异生作用,改善奶牛能量平衡,适宜添加量为300mL.d-1。     

Effects of different sources of carbohydrates on intake,digestibility, chewing,and performance of Holstein dairy cows

To investigate the effects of different sources of carbohydrates on intake, digestibility, chewing, and performance, nine lactating Holstein dairy cows (day in milk= 100±21 d; body weight=645.7 ± 26.5 kg) were allotted to a 3 × 3 Latin square design at three 23-d periods. The three treatments included 34.91% (B), 18.87% (BC), and 18.86% (BB) barley that in treatment B was partially replaced with only corn or corn plus beet pulp in treatments BC and BB, respectively. The concentration of starch and neutral detergent soluble carbohydrate varied (22.2, 20.2, and 14.5; 13.6, 15.9, and 20.1% of DM in treatments B, BC, and BB, respectively). Cows in treatment BB showed a higher DMI and improved digestibility of DM, NDF, and EE compared with treatments B or BC. Ruminal pH was higher in cows fed on BB (6.83) compared with those that received B or BC treatments (6.62 and 6.73, respectively). A lower proportion of propionate accompanied the higher pH in the BB group; however, a greater proportion of acetate and acetate: propionate ratio was observed compared with cows fed either on the B or BC diet. Moreover, cows fed on the BB diet showed the lowest ruminal passage rate and longest ruminal and total retention time. Eating time did not differ among treatments, rumination time was greater among cows fed on the BB diet compared with the others, whereas total chewing activity was greater than those fed on BC, but similar to those fed on B. The treatments showed no effect on milk yield. Partially replacing barley with corn or beet pulp resulted in an increase in milk fat and a lower protein concentration. Changing dietary NFC with that of a different degradability thus altered intake, chewing activity, ruminal environment, retention time or passage rate, and lactation performance. The results of this study showed that beet pulp with a higher NDF and a detergent-soluble carbohydrate or pectin established a more consistent ruminal mat than barley and corn, thus resulting in higher mean retention time and chewing activity, whereas no changes in 3.5% FCM and milk fat were observed.     

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.     

Effect of milking frequency in early lactation on energy metabolism, milk production and reproductive performance of dairy cows

The objective of this study was to evaluate the effect of imposing different milking frequencies for the first 4 weeks of lactation on energy balance, blood metabolic profiles and reproductive performance. The milking frequencies imposed were once daily for the first 4 weeks of lactation and twice daily subsequently (X1), twice daily for the entire lactation (X2) and three times daily for the first 4 weeks of lactation and twice daily subsequently (X3). Two weeks prior to the first expected calving date, sixty-three multiparous, Holstein-Friesian cows, were allocated to treatments based on expected calving date, parity (lactation number = 2 and lactation number > 2), BCS and BW. Mean DMI was lower (P < 0.05) on X1 than X2 (15.7 and 17.1 kg/day) over the first 4 weeks of lactation, but DMI on X3 was not different to either. Milk yield was lower (P < 0.05) on X1 than on X2 and X3 (24.1, 31.9 and 31.4 kg/day) from weeks 1 to 4 and at week 10 of lactation (30.9, 33.9 and 33.7 kg/day) but was not different at week 20. Yield of milk constituents followed the same pattern as milk yield. Milking frequency had no significant effect on milk fat or protein concentration but milk lactose concentration was higher (P < 0.05) on X1 than on X2. Cows on X1 experienced less (P < 0.05) negative energy balance than those on X2 and X3 from weeks 1 to 4, with no difference between X2 and X3. Cows on X1 lost less BW (P < 0.05) from weeks 1 to 4 and lost less BCS up to day 73 of lactation than cows on X2 and X3. Plasma NEFA and BHB concentrations tended to be lower and plasma glucose tended to be higher on X1 than on X2 and X3 from weeks 1 to 4, while plasma insulin was higher on X1 than on X2 and X3 for the first 2 weeks of lactation. There was no difference between treatments in any reproductive performance variable measured. These results indicate that reduced milking frequency decreases milk yield and improves energy balance and metabolic status in early lactation.     

Plasma mineral and energy metabolite concentrations in dairy cows fed an anionic prepartum diet that did or did not have retained fetal membranes after parturition

OBJECTIVE: To compare plasma total calcium, phosphorus, magnesium, nonesterified fatty acids (NEFA), beta hydroxy butyrate (BHB), and glucose concentrations in parturient dairy cows that were fed an anionic prepartum diet between those with and without retained fetal membranes (RFM) at 24 hours after parturition. ANIMALS: 152 Holstein cows that calved during October through December of 1997 PROCEDURE: All cows were fed an anionic prepartum diet. Blood sample was taken within 6 hours after parturition from randomly selected cows. Thirty-nine cows had a diagnosis of RFM at 24 hours after parturition; 113 were not affected with RFM. At calving, body condition score (BCS; 1 [thin] to 5 [obese]), parity, and calving difficulty score were recorded. Plasma calcium, phosphorus, magnesium, NEFA, BHB, and glucose concentrations were compared between cows with or without RFM. RESULTS: Cows with RFM had significantly lower plasma calcium concentration soon after calving, compared with cows without RFM. Cows with a parity of > or = 3 had significantly lower plasma concentrations of calcium and higher concentrations of magnesium, compared with cows with a parity of 1 or 2. Cows with a BCS of > or = 3.25 at calving had significantly higher plasma concentrations of BHB than cows with a BCS of 2.75 to 3.0. Cows with dystocia had significantly higher plasma concentrations of glucose, compared with cows without dystocia. CONCLUSIONS AND CLINICAL RELEVANCE: In parturient cows fed a prepartum anionic diet, those with RFM have lower plasma calcium concentrations than cows without RFM, although this association does not prove a cause-effect relationship.