Energy Status Of Dairy Cows Research Articles

MiRNome variations in milk fractions during feed restrictions of different intensities in dairy cows

BackgroundIn dairy cows, diet is one factor that can affect their milk production and composition. However, the effect of feed restriction on milk miRNome has not yet been described. Indeed, milk is the body fluid with the highest RNA concentration, which includes numerous microRNA. Its presence in the four different milk fractions, whole milk, fat globules, mammary epithelial cells and extracellular vesicles, is still poorly documented. This study aimed to describe the effects of different feed restrictions on the miRNome composition of different milk fractions.ResultsTwo feed restrictions were applied to lactating dairy cows, one of high intensity and one of moderate intensity. 2,896 mature microRNA were identified in the different milk fractions studied, including 1,493 that were already known in the bovine species. Among the 1,096 microRNA that were sufficiently abundant to be informative, the abundance of 1,027 of them varied between fractions: 36 of those were exclusive to one milk fraction. Feed restriction affected the abundance of 155 microRNA, with whole milk and milk extracellular vesicles being the most affected, whereas milk fat globules and exfoliated mammary epithelial cells were little or not affected at all. The high intensity feed restriction led to more microRNA variations in milk than moderate restriction. The target prediction of known microRNA that varied under feed restriction suggested the modification of some key pathways for lactation related to milk fat and protein metabolisms, cell cycle, and stress responses.ConclusionsThis study highlighted that the miRNome of each milk fraction is specific, with mostly the same microRNA composition but with variations in abundance between fractions. These specific miRNomes were affected differently by feed restrictions, the intensity of which appeared to be a major factor modulating milk miRNomes. These findings offer opportunities for future research on the use of milk miRNA as biomarkers of energy status in dairy cows, which is affected by feed restrictions.

Possibility to Estimate Same Day Energy Status of Dairy Cows during First Half of Lactation by Non-Invasive Markers with Emphasis to Milk Fatty Acids.

Postpartum negative energy balance (NEB) is detrimental to cows and decreases profitability in dairy farming. The two origins of milk fatty acids (FA), de novo synthesized in the mammary gland and plasma lipids initially originating from feed, rumen microbes and the animal's adipose tissue, make milk FA candidates as possible NEB biomarkers. The aim of this study was to assess the possibility to predict EB in cows in the first 150 days of lactation with BCS, milk traits and selected individual milk FA and the ratios of blood-derived and de novo synthesized FA. The daily EB of Estonian Holstein cows (N = 30) was calculated based on body weights and BCS values. Milk FA were analyzed with gas chromatography. The variance partitioning analysis revealed that milk production traits, BCS at calving, FA ratios and days in milk accounted for 67.1% of the EB variance. Random forest analysis indicated the highest impact of the ratios C18:1cis9/C12:0+C14:0, C18:1cis9+C18:0/C12:0+C14:0, C18:1cis9/C14:0, C18:1cis9+C18:0/C14:0, C18:1cis9/sum C5:0 to C14:0, C18:1cis9+C18:0/sum C5:0 to C14:0 or C18:1cis9/C15:0. FA and their ratios alone explained 63.6% of the EB variance, indicating the possibility to use milk FA and their ratios as sole predictors for the energy status in dairy cows.

Milk 13C and 15N discriminations as biomarkers of feed efficiency and energy status in early lactation cows

Measuring feed utilization efficiency (FUE, milk production / feed intake) and energy status of dairy cows is essential to optimize dairy management and reduce feed waste, but FUE measurement is laborious and costly for dairy farms, particularly when cows are fed in groups. Our study was to investigate whether milk 13C and 15N stable isotope discriminations (naturally existing isotope; milk δ13C or δ15N – diet δ13C or δ15N) were used as biomarkers to estimate FUE, energy balance, and milk production of early lactation cows. Ten multiparous lactating cows with similar body weight (mean ± SD; 691 ± 18.0 kg) and parity (1.6 ± 0.5) were fed a homogeneous diet from 4 to 11 wk postpartum. Body fat had 1.5‰ less δ13C (P < 0.001) and muscle had similar δ13C compared to animal diet. Muscle had more than 2‰ greater δ15N than the diet (P < 0.0001). Milk 13C discrimination was reduced (P = 0.04) and milk 15N discrimination was increased (P < 0.0001) as lactation progressed postpartum. In early lactation, milk 13C discrimination was positively correlated with net energy balance (NEl) (linear; R2 = 0.49), and milk 15N discrimination was negatively correlated with NEl balance (linear; R2 = 0.56). Meanwhile, milk 13C discrimination was negatively and linearly (R2 = 0.30) correlated with feed carbon utilization efficiency, and milk 15N discrimination was positively and linearly (R2 = 0.55) correlated with feed nitrogen utilization efficiency. For milk production, milk 13C discrimination was negatively and linearly correlated with the milk yield (R2 = 0.44), milk fat yield (R2 = 0.40) and lactose yield (R2 = 0.46). Milk 15N discrimination was positively and linearly correlated with the milk protein yield (R2 = 0.49). Collectively, our data revealed that milk 13C and 15N discriminations could be as biomarkers to estimate the FUE, energy status, and milk production of early lactating cows. Potentially, measuring milk isotopic discrimination may be also applied to understand energy and nutrient partitioning of internal C and N reservoirs (body fat and muscle) for supporting milk synthesis in early lactation.

Analysis of the genetic architecture of energy balance and its major determinants dry matter intake and energy-corrected milk yield in primiparous Holstein cows

The focus of modern dairy cow breeding programs has shifted from being mainly yield based toward balanced goals that increasingly consider functional traits such as fertility, metabolic stability, and longevity. To improve these traits, a less pronounced energy deficit postpartum is considered a key challenge. On the other hand, feed efficiency and methane emissions are gaining importance, possibly leading to conflicts in the design of breeding goals. Dry matter intake (DMI) is one of the major determinants of energy balance (EB), and recently some efforts were undertaken to include DMI in genomic breeding programs. However, there is not yet a consensus on how this should be achieved as there are different goals in the course of lactation (i.e., reducing energy deficit postpartum vs. subsequently improving feed efficiency). Thus, the aim of this study was to gain more insight into the genetic architecture of energy metabolism across lactation by genetically dissecting EB and its major determinants DMI and energy-corrected milk (ECM) yield at different lactation stages applying random regression methodology and univariate and multivariate genomic analyses to data from 1,174 primiparous Holstein cows. Daily heritability estimates ranged from 0.29 to 0.49, 0.26 to 0.37, and 0.58 to 0.68 for EB, DMI, and ECM, respectively, across the first 180 d in milk (DIM). Genetic correlations between ECM and DMI were positive, ranging from 0.09 (DIM 11) to 0.36 (DIM 180). However, ECM and EB were negatively correlated (rg = -0.26 to -0.59). The strongest relationship was found at the onset of lactation, indicating that selection for increased milk yield at this stage will result in a more severe energy deficit postpartum. The results also indicate that EB is more affected by DMI (rg = 0.71 to 0.81) than by its other major determinant, ECM. Thus, breeding for a higher DMI in early lactation seems to be a promising strategy to improve the energy status of dairy cows. We found evidence that genetic regulation of energy homeostasis is complex, with trait- and lactation stage-specific quantitative trait loci suggesting that the trajectories of the analyzed traits can be optimized as mentioned above. Especially from the multivariate genomic analyses, we were able to draw some conclusions on the mechanisms involved and identified the genes encoding fumarate hydratase and adiponectin as highly promising candidates for EB, which will be further analyzed.

Monitoring predictive and informative indicators of the energy status of dairy cows during early lactation in the context of monthly milk recordings using mid-infrared spectroscopy

With the onset of lactation, voluntary feed intake does not increase as fast as the milk yield and the energy balance (EB) becomes physiologically negative. The risk of metabolic disorders increases with decreasing EB. During this time the concentration of ß-hydroxybutyrate (BHB) in serum increases. Herd managers cannot calculate the EB as the feed intake is commonly not quantified. Measuring the concentration of BHB in serum is generally not feasible on farms because blood samples must be collected and the respective analyses run. The motivation for developing the presented models was to be able to utilise the potential of the mid-infrared (MIR) spectroscopy spectral data (as part of the monthly milk recording)) for predicting the extensive energy status indicators EB and the BHB in serum in the first crucial lactation weeks (LW). In the first 10 LW, milk and blood samples were sampled from 65 primiparous (n = 20) and multiparous (n = 45) German Holstein cows. Milk samples were analysed by the laboratory of the milk recording organisation (MRO). For the reference data, blood samples were taken for BHB analysis and the EB of each cow was calculated using automatic weighing troughs for the energy intake. To predict the indicators of energy status, linear regression models that are easily applied in real-time were combined with milk spectral data, milk component data, and information on animal lactation number and stage. The linear regression model obtained better accuracy than the partial least square. In the first 4 LW the best linear regression model reached R2 = 0.55 for EB in the multiparous cows (MC) and R2 = 0.83 for EB in the primiparous cows (PC); the best model for the 5th to 10th LW reached R2 = 0.57 for EB in the MC and R2 = 0.71 for EB in the PC. To predict serum BHB in the first 4 LW the best linear regression model reached R2 = 0.42. Sensitivity (sen) and specificity (spec) were calculated (cut-off values: BHB 1200 µmol/L; EB 5% percentile). Cows at risk of an energy status imbalance during early lactation can be screened by the prediction of EB (and serum BHB) in the context of the monthly milk recording. These data provide a basis for further individual animal or herd-based steps to attenuate the risk for diseases in early lactation.

Milk fatty acid composition as an indicator of energy status in Holstein dairy cows

Abstract. Transition dairy cows often enter a stage of negative energy balance during which the utilization of energy reserves is reflected in the milk fatty acid (FA) composition. In this study, metabolic status was evaluated by measuring milk FA, ruminal short-chain FA (RSCFA), and serum biochemical parameters in Holstein cows. Samples (milk, rumen contents, and blood) were collected around days 30 (early) and 150 (middle) of lactation, and rumen contents and blood samples were collected 30 days before calving (dry). Fatty acids were extracted and FA composition was determined. Glucose, triacylglycerols, total cholesterol, low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), beta-hydroxybutyric acid (BHB), and non-esterified fatty acid (NEFA) concentrations were determined in serum samples. Lower percentages of saturated FA in milk and higher percentages of monounsaturated FA, polyunsaturated FA, and C18:1n-9 were observed in early lactation compared to mid-lactation. In rumen higher concentrations of propionic acid were determined at mid-lactation compared to early lactation. Acetic and butyric acid concentrations showed no significant differences between sampling intervals. In serum higher glucose concentrations were observed during the dry period and mid-lactation than during early lactation. Lower BHB and higher NEFA concentrations were noted during early lactation compared to mid-lactation and the dry period. Total cholesterol, LDL-C, HDL-C and triacylglycerols showed no significant differences between sampling intervals. The results of the present study suggest that determination of milk FA is a potential indicator of energy status in dairy cows.

The effects of fructose and phosphate infusions on dry matter intake of lactating cows

The objective of this study was to examine the effects of fructose and phosphate (Pi) infusions on dry matter intake by dairy cows to further understand the mechanisms controlling feed intake related to hepatic energy status. We performed 3 experiments in which we infused fructose and Pi intravenously or abomasally to Holstein cows. The first experiment used 8 cows (4-8 d postpartum) in a duplicated 4 × 4 Latin square experiment with 1 square of multiparous and 1 square of primiparous cows. A 2 × 2 factorial arrangement of treatments was used including jugular infusions of solutions (1 L/h) containing fructose or glucose (0.6 mol/h) and Pi (NaH2PO4) or NaCl (0.3 mol/h). Periods were 24 h, including 2 h for infusions and 22 h for recovery. The second experiment used 4 multiparous cows (74-81 d postpartum) in a 4 × 4 Latin square design and infused fructose or glucose and either Pi or no Pi at the same rates as experiment 1. Periods were 24 h, including 1 h for infusions and 23 h for recovery. The third experiment used 4 ruminally cannulated multiparous cows (15-26 d postpartum) in a 4 × 4 Latin square design and infused fructose or glucose and either Pi or NaCl at the same rates as experiment 1 but to the abomasum. Periods were 24 h, including 1 h for infusions and 23 h for recovery. In each experiment, feed intake was recorded by a computerized data acquisition system; blood was analyzed for the concentrations of glucose, nonesterified fatty acids, and Pi; and the liver was analyzed for the concentration of Pi (experiments 2 and 3 only). Overall, fructose infusion increased DMI by fresh cows when infused intravenously and abomasally, but it did not affect DMI by mid-lactation cows. Fructose infusion also reduced hepatic Pi, and Pi infusion increased hepatic Pi when infused abomasally but not intravenously. These results suggest that fructose increases feed intake, likely by sequestering Pi and preventing ATP production. When infused intravenously to multiparous cows, Pi increased DMI and did not affect hepatic Pi content. However, when infused abomasally, Pi reduced DMI and increased hepatic Pi content. These results suggest that although Pi infusion prevents the effect of fructose loading and reduces DMI, it also increases intake through a competing mechanism. Examining long-term effect of Pi infusion on DMI could determine if competing mechanisms complicate the determination of P requirement for dairy cows. These results are consistent with the control of feed intake by hepatic energy status in dairy cows.

Feeding glycerol-enriched yeast culture improves lactation performance, energy status, and hepatic gluconeogenic enzyme expression of dairy cows during the transition period1

This study aimed to evaluate the effects of feeding glycerol-enriched yeast culture (GY) on feed intake, lactation performance, blood metabolites, and expression of some key hepatic gluconeogenic enzymes in dairy cows during the transition period. Forty-four multiparous transition Holstein cows were blocked by parity, previous 305-d mature equivalent milk yield, and expected calving date and randomly allocated to 4 dietary treatments: Control (no additive), 2 L/d of GY (75.8 g/L glycerol and 15.3 g/L yeast), 150 g/d of glycerol (G; 0.998 g/g glycerol), and 1 L/d of yeast culture (Y; 31.1 g/L yeast). All additives were top-dressed and hand mixed into the upper one-third of the total mixed ration in the morning from -14 to +28 d relative to calving. Results indicated that the DMI, NE intake, change of BCS, and milk yields were not affected by the treatments ( > 0.05). Supplementation of GY or Y increased milk fat percentages, milk protein percentages, and milk protein yields relative to the Control or G group ( < 0.05). Cows fed GY or G had higher glucose levels and lower β-hydroxybutyric acid (BHBA) and NEFA levels in plasma than cows fed the Control ( < 0.05) and had lower NEFA levels than cows fed Y ( < 0.05). On 14 d postpartum, cows fed GY or G had higher enzyme activities, mRNA, and protein expression of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C; < 0.05); higher enzyme activities ( < 0.05) and a tendency toward higher mRNA expression ( < 0.10) of glycerol kinase (GK); and a tendency toward higher enzyme activities of pyruvate carboxylase (PC) in the liver ( < 0.10) when compared with cows fed Control or Y. The enzyme activities, mRNA, and protein expression of PEPCK-C, PC, and GK did not differ between cows fed GY and G ( > 0.10). In conclusion, dietary GY or Y supplementation increased the milk fat and protein content of the cows in early lactation and GY or G supplementation improved the energy status as indicated by greater plasma glucose and lower plasma BHBA and NEFA concentrations and upregulated the hepatic gluconeogenic enzymes of dairy cows during the transition period. Feeding cows with a GY mixture in the peripartum period combined the effects of yeast on lactation performance and the effects of glycerol on energy status in dairy 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.

Influence of energy and nutrient supply pre and post partum on performance of multiparous Simmental, Brown Swiss and Holstein cows in early lactation

A study was conducted to evaluate the effects of pre partum (PRE) and post partum (POST) dietary energy and nutrient supply (E) and their interactions on feed intake, performance and energy status in dairy cows of three breeds. In this experiment, the effects of three energy and nutrient supply levels (low (L), medium (M), high (H)), both pre-calving and post-calving, were investigated, using a 3×3 factorial arrangement of treatments. In both phases (84 days pre- and 105 days post-calving) 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 (GfE). Dry matter intake (DMI) was restricted, if energy intake exceeded target values. Pre partum DMI and energy intake were different as designed, liveweight and body condition score (BCS) of SI cows were higher, but EB was lower, compared to BS and HF cows. Milk yield and composition were influenced by all three main experimental factors (EPRE, EPOST, breed). Energy-corrected milk yield was 25.6, 28.6 and 30.1 kg/day for LPRE, MPRE and HPRE as well as 21.5, 30.1 and 32.6 kg/day for LPOST, MPOST and HPOST, respectively. Numerically, only for milk protein content the interactions EPRE×EPOST and EPRE×breed reached significance. Impact of energy supply pre-calving was more pronounced when cows had lower energy supply post-calving and vice versa. On the other hand, milk yield response of cows to energy supply above requirements was greater for cows that were fed on a low energy level pre partum. Impact of energy level pre partum was higher for HF cows, showing that their milk production relies to a greater extent on mobilization of body reserves. Increasing energy supply pre partum led to a more negative energy balance post partum, mainly by increasing milk yield and content, whereas feed intake was slightly reduced. Increasing energy supply post partum enhanced milk yield as well as milk protein and lactose content. Calculated energy balance corresponded well with liveweight and BCS change. Response of milk yield to increasing energy supply followed the principle of diminishing returns, since energy was increasingly partitioned to body retention. Increasing energy supply pre partum enhances milk yield and content post partum, but exacerbates negative energy balance and its consequences.

Relationship between body condition score and ultrasound measurement of backfat thickness in multiparous Holstein dairy cows at different production phases

The validity of the body condition score (BCS) for evaluating subcutaneous fat has been questioned because of its subjectivity. With the advent of ultrasonography, backfat thickness (BFT) can be objectively measured and used to assess the energy status of dairy cows in conjunction with BCS. Determine the relationship between BCS and ultrasound measurements of BFT throughout the lactation cycle. Cows (n = 1123) were selected randomly and classified according to their lactation stage into four different groups. BCS was determined using a 5-point scale and BFT measurements were obtained using a 5-MHz linear transducer. The correlation coefficient (r) for the relationship between BCS and BFT varied according to the stage of lactation. There was a high correlation (r = 0.96-0.98) and relationship (r(2) = 0.92-0.96) between BCS and BFT. The highest correlation was found at BFT values of 10-35 mm and BCS of 2-4.5 units. BCS is a practical tool for evaluating body condition; furthermore, it may be as valid as BFT for the estimation of subcutaneous fat in Holstein dairy cows over time.

Use of metabolic profiles and body condition scoring for the assessment of energy status of dairy cows

The aim of this study was to assess the significance of body condition scoring and metabolic profile test for estimation of energy status of healthy high-yielding dairy cows. Twenty one healthy cows (primiparous and secundiparous) were divided into three groups: dry cows, early puerperal cows and early lactating cows. Cow?s energy status was estimated by the analysis of blood samples for beta-hydroxybutirate (BHBA) and glucose. Additionally, urea, total bilirubine and total protein were measured in blood serum samples. According to body condition scores (BCS) results dry cows were overweight (4.03?0.29 points). Immediately after calving, cows lost their weight significantly, since BCS was 2.85?0.46 points at puerperal period and 3.12?0.33 points at day 60 of lactation (p&lt;0.001 compared to dry period, respectively). Glucose concentration did not change significantly between dry and puerperal period, while BHBA increased significantly (0.46?0.14 mmol/l at dry period to 1.08?0.21 mmol/l at puerperal period; p&lt;0.001). Urea concentration did not change significantly during examined period. Total bilirubin concentration significantly increased from dry (6.31?0.37 mmol/l) to puerperal period (7.63?2.52 mmol/l; p&lt;0.001 compared to dry period) and remained high until day 60 of lactation (7.62?0.13 mmol/l; p&lt;0.001 compared to dry period). Total protein concentration decreased from dry to puerperal period (69.59?6.14 g/l to 58.87?3.29 g/l; p&lt;0.001). According to obtained results it can be concluded that cows were not in adequate energy status during transition period. Our results also indicate that, body condition scoring, BHBA and total bilirubin concentrations can be used as reliable indicators of cow?s energy status even when there are not clinically visible health disorders.

Milk fatty acid profile related to energy balance in dairy cows

Milk fatty acid (FA) profile is a dynamic pattern influenced by lactational stage, energy balance and dietary composition. In the first part of this study, effects of the energy balance during the proceeding lactation [weeks 1-21 post partum (pp)] on milk FA profile of 30 dairy cows were evaluated under a constant feeding regimen. In the second part, effects of a negative energy balance (NEB) induced by feed restriction on milk FA profile were studied in 40 multiparous dairy cows (20 feed-restricted and 20 control). Feed restriction (energy balance of -63 MJ NEL/d, restriction of 49 % of energy requirements) lasted 3 weeks starting at around 100 days in milk. Milk FA profile changed markedly from week 1 pp up to week 12 pp and remained unchanged thereafter. The proportion of saturated FA (predominantly 10:0, 12:0, 14:0 and 16:0) increased from week 1 pp up to week 12 pp, whereas monounsaturated FA, predominantly the proportion of 18:1,9c decreased as NEB in early lactation became less severe. During the induced NEB, milk FA profile showed a similarly directed pattern as during the NEB in early lactation, although changes were less marked for most FA. Milk FA composition changed rapidly within one week after initiation of feed restriction and tended to adjust to the initial composition despite maintenance of a high NEB. C18:1,9c was increased significantly during the induced NEB indicating mobilization of a considerable amount of adipose tissue. Besides 18:1,9c, changes in saturated FA, monounsaturated FA, de-novo synthesized and preformed FA (sum of FA >C16) reflected energy status in dairy cows and indicated the NEB in early lactation as well as the induced NEB by feed restriction.

The effect of body condition score at calving and supplementation with Saccharomyces cerevisiae on milk production, metabolic status, and rumen fermentation of dairy cows in early lactation

The objective of this study was to examine the effects of live yeast (LY) supplementation and body condition score (BCS, 1–5 scale) at calving on milk production, metabolic status, and rumen physiology of postpartum (PP) dairy cows. Forty Holstein-Friesian dairy cows were randomly allocated to a 2 × 2 factorial design and blocked by yield, parity, BCS, and predicted calving date. Treatments were body condition at calving (low for BCS ≤3.5 or high for BCS ≥3.75; n=20) and supplementation with LY (2.5 and 10g of LY/d per cow for pre- and postcalving, respectively; control, no LY supplementation; n=20). The supplement contained 109 cfu of Saccharomyces cerevisiae/g (Yea-Sacc1026 TS, Alltech Inc., Nashville, TN). Daily milk yield, dry matter intake, milk composition, BCS, body weight, and backfat thickness were recorded. Blood samples were harvested for metabolite analysis on d 1, 5, 15, 25, and 35 PP. Liver samples were harvested by biopsy for triacylglycerol (TAG) and glycogen analysis on d 7 precalving, and on d 7 and 21 PP. Rumen fluid was sampled by rumenocentesis for all cows on d 7 and 21 PP. Supplementation with LY had no effect on milk yield, dry matter intake, rumen fluid pH, or blood metabolites concentration of dairy cows with high or low BCS at calving. Feeding LY increased rumen acetate proportion and protozoal population, tended to increase liver glycogen, and decreased rumen ammonia nitrogen during early lactation. Over-conditioned cows at calving had greater body reserve mobilization and milk production and lower feed intake, whereas cows with a moderate BCS at calving had greater feed intake, lower concentrations of nonesterified fatty acids and β-hydroxybutyrate, lower liver TAG and TAG:glycogen ratio, and faster recovery from body condition loss. Additionally, the data suggest that concentrations of liver enzymes in blood might be used as an indicator for liver TAG:glycogen ratio. Results indicate that in the case of this experiment, where the control treatment was associated with an acceptable rumen pH, feeding yeast did not significantly improve indicators of energy status in dairy cows.

Association between uterine disease and indicators of neutrophil and systemic energy status in lactating Holstein cows

The objective of this study was to evaluate the association between uterine disease and indicators of neutrophil (PMN) and systemic energy status in dairy cows. Peripheral blood (120mL) was collected weekly from 84 Holstein cows for PMN isolation and plasma collection from calving until 42 d in milk (DIM). The final analysis included 80 cows. Of those, 20 cows were classified as having metritis (fetid uterine discharge and fever), 15 as having subclinical endometritis (SCE; ≥10% PMN on uterine cytology), and 45 as healthy controls. Plasma haptoglobin concentration was increased only in cows that developed metritis. Neutrophil glycogen content was reduced in cows developing metritis compared with healthy cows on the day of calving and at 7 and 42 DIM. Cows with SCE had lower PMN glycogen content than healthy cows at 7, 28, and 42 DIM. Blood glucose was affected by disease status within parity. Primiparous metritis cows had greater blood glucose concentrations than healthy primiparous cows. Multiparous metritis cows tended to have lower blood glucose concentration than multiparous SCE cows. Cows that developed metritis and SCE had or tended to have greater NEFA and BHBA than healthy cows, mainly around calving. At calving, cows that developed metritis had higher plasma estradiol concentration than healthy cows and greater plasma cortisol than cows that had SCE. Plasma insulin was not affected. Plasma glucagon was increased for SCE cows. Cows that developed uterine disease experienced a greater degree of negative energy balance and had decreased lower intracellular PMN glycogen levels, which could be a major predisposing factor for disease because of decreased availability of oxidative fuels.

The effect of body condition at calving and supplementation with Saccharomyces cerevisiae on energy status and some reproductive parameters in early lactation dairy cows

Improving the energy status of dairy cows during the early post-partum (PP) period by adding a safe dietary supplement such as live yeast culture (YS) may have a positive effect on reproductive function. The objective was to examine potential benefits of YS supplementation on PP energy status and fertility indices of dairy cows managed to have low or high body condition score (BCS, 1–5 scale) at calving. Forty (10 primiparous and 30 multiparous) Holstein/Friesian dairy cows were blocked by yield, parity, BCS, and predicted calving date. Within each block, cows were randomly allocated to a 2 × 2 factorial arrangement of treatments which were: BCS at calving (low ≤3.5 or high ≥3.75; n = 20) and YS supplementation (2.5 g/cow/day for pre-calving and 10 g/cow/day for post-calving × 10 8 CFU of Saccharomyces cerevisiae/g) (supplemented or control; n = 20). Daily milk yield was recorded and weekly milk composition, BCS and BW were assessed from calving to week 10 PP. Forage (100% grass silage pre-calving; 50% grass silage, 50% maize silage post-calving; ad libitum) intake was recorded individually. Concentrate (2 kg of pre-calver nuts ± YS for pre-calving and 8 kg of lactating nuts ± YS for post-calving) feeding was controlled individually. Estimated energy balance PP was calculated on a weekly basis individually as the difference between the net energy (NE) intake and the sum of NE for maintenance and milk production. Insulin and IGF-I concentrations were determined on days 14 and 7 pre-calving and 1, 5, 15, 25 and 35 post-calving. Daily ovarian ultrasonography was performed from day 10 PP to monitor the size and development of the first dominant follicle (>10 mm in diameter with absence of other large growing follicles), first ovulatory follicle and days to first ovulation PP. Pre-ovulatory peak of serum oestradiol concentration was determined during the 2 days before ovulation day. Cows with high BCS (over-conditioned) at calving ingested less NE, produced more milk NE output, and consequently had a significantly ( P < 0.05) exacerbated negative energy balance in comparison with low BCS cows (moderately conditioned) during early lactation. Higher ( P < 0.05) insulin concentrations and a tendency for higher ( P = 0.06) pre-ovulatory peak oestradiol concentrations in low BCS group were detected in the early PP period. Supplementing the diet with YS had no effect ( P > 0.10) on NE intake, NE milk output or energy balance. On the other hand it increased ( P < 0.01) insulin concentration and tended to increase ( P = 0.07) pre-ovulatory peak oestradiol concentrations and the size of first ovulatory follicle ( P = 0.09) early PP. Feeding YS had no effect on energy status of lactating dairy cows with high or low BCS at calving, whilst it improved serum insulin concentration, pre-ovulatory peak of oestradiol and the size of first ovulatory follicle in the early PP period. These observed effects of YS supplementation require to be substantiated with further research.

Determination of organic components of milk as method for evaluating energy status of dairy cows

The objective of the investigations described in this work was to determine the energy status and to make recommendations for correcting the cow diet at a farm of high-yield dairy cows, on the grounds of values for the concentration of organic components of milk and their ratios in individual milk samples. A total of 147 cows were examined, including 97 in the first and 50 in the second lactation. Average concentrations of milk fat and urea were within the physiological values. Namely, the milk fat concentration in cows in the first lactation was 38.88?5.07 g/l, and it was 36.47?4.82 g/l in cows in the second lactation, while the urea concentration in cows in the first lactation 3.16?0.58 mmol/l and it was 3.72?0.64 mmol/l in cows in the second lactation. The protein concentration in both groups of cows was below the physiological values, being 30.33?2.35 g/l in cows in the first lactation and 30.17?2.27 g/l in cows in the second lactation. Based on the ratio of urea and protein concentrations, as well as of fat and proteins in the individual milk samples, it was concluded that in most examined cows, both in those in the first and those in the second lactation, there is a deficit of energy, along with a deficit or relative surplus of proteins. On the grounds of the obtained results, recommendations were given for correcting the feed rations in the coming period. .

Strategies to improve fertility of high yielding dairy farms: Management of the dry period

Reproductive performance of dairy cattle has been related to a wide variety of indicators of energy status, e.g., extent of negative energy balance, time of energy balance nadir, body weight loss, body condition score, and body condition score loss. Energy balance begins to decrease during the last few weeks prior to calving primarily due to a 30–35% reduction in feed intake. Cows typically remain in negative energy balance for five to seven weeks postpartum. Nutritional strategies to improve energy balance during the transition period include fat supplementation and feeding additional nonfiber carbohydrate. Unfortunately, neither approach is likely to markedly enhance energy status, although fat supplementation may increase reproductive efficiency independent of any effect on energy balance. Alternative management strategies may be required to improve fertility of dairy cows. Shortening or eliminating the dry period may improve energy status of dairy cows and increase reproductive efficiency. Shortening or eliminating the dry period may enhance dry matter intake during the transition period, decrease milk energy output, or both. A preliminary study using small animal numbers indicated that reducing dry period length to 28 or 0 days may decreases days to first ovulation, increase first service conception rate, and decrease days open. A follow-up study employing large animal numbers confirmed that reducing dry period length from 55 to 34 days can decrease days to first ovulation and decrease the percentage of anovular cows. The reduction in days open was greater for older cows than second parity cows. The reduction in days open was not related to effects of treatment on milk yield. Shortening or eliminating the dry period may be a more successful approach to improving reproductive efficiency than diet manipulation.

Effect of encapsulated conjugated linoleic acid isomers on carcass composition of beef steers

Dietary supplements of a mixture of CLA isomers have been shown to reduce body fat accretion in mice and pigs with the trans-10, cis-12 isomer probably being responsible for the anti-lipogenic effects. The efficacy of calcium salts of a mixture of CLA methyl esters containing trans-10, cis-12, on milk fat synthesis, is relatively low (Bernal-Santos et al., 2003) and reported lack of effects on growth may be due to low efficacy and the short duration of CLA supplementation, during the last 32 or 60 days before slaughter, and the relatively low level of trans-10, cis-12 CLA fed. Shingfield et al (2004) demonstrated the potential of rumen protected supplements of a mixture of CLA isomers to reduce milk fat content and improve the energy status of dairy cows during early lactation. The current experiment used a lipid-encapsulated supplement containing equal amounts of cis-9, trans-11 and trans-10, cis-12 CLA methyl esters to study the effects on the performance and carcass characteristics of Limousin steers during a 100d finishing period.

Energy status of dairy cows determined by biochemical analysis of organic components of milk

Valid indicators of the energy status of cows are the body condition, parameters of the metabolic profile, hormonal status, and organic components of milk. The energy status of cows of the Holstein-Friesian breed from four farms was estimated on the grounds of urea, protein and fat concentration in milk. Investigations covered 62 samples of milk (11 from farm A, 16 from farm B, 15 from farm C, and 20 from farm D). All cows were in the first stage of lactation and fed rations recommended for that category of animal. The average fat concentration in all milk samples was 23?13 g/l, the average protein concentration was 29?3 g/l, while the average urea concentration was 4.6?1.3 mmol/l. It could be concluded on the basis of the value for the milk fat concentration alone that a decreased milk fat syndrome was present. In addition, graphic presentations are given for the relation between urea concentration and protein concentration, as well as protein and fat concentrations in the individual milk samples. Such an analysis provided a more detailed picture of the energy status of the examined cows. It was established that cows on farm A had a deficiency of energy and protein, and cows on farms B and C a deficiency of energy with a relative surplus of proteins. It was established that cows from farm D had a deficiency of energy, and there was an equal number of cows with a deficiency and with a relative surplus of proteins. The obtained results provide grounds for making recommendations for correcting the feed rations and improving the health of the cows. It stems from the obtained results that the determination of urea, fat and protein concentrations in milk is a reliable indicator of the energy status of cows, that it is rational and financially acceptable for every producer, regardless of whether it is implemented in small or large cattle farms. The diagnostic procedures used so far have been implemented in a limited form in daily practice because of insufficient reliability (evaluation of body condition) or lack of economic feasibility (metabolic profile and hormonal status of cows).