Primiparous Holstein-Friesian Cows Research Articles

Influence of the concentrate inclusion level in a grass silage–based diet on hepatic transcriptomic profiles in Holstein-Friesian dairy cows in early lactation

Excessive negative energy balance in early lactation is linked to an increased disease risk but may be mitigated by appropriate nutrition. The liver plays central roles in both metabolism and immunity. Hepatic transcriptomic profiles were compared between 3 dietary groups in each of 40 multiparous and 18 primiparous Holstein-Friesian cows offered isonitrogenous grass silage-based diets with different proportions of concentrates: (1) low concentrate (LC, 30% concentrate + 70% grass silage); (2) medium concentrate (MC, 50% concentrate + 50% grass silage), or (3) high concentrate (HC, 70% concentrate + 30% grass silage). Liver biopsies were taken from all cows at around 14 d in milk for RNA sequencing, and blood metabolites were measured. The sequencing data were analyzed separately for primiparous and multiparous cows using CLC Genomics Workbench V21 (Qiagen Digital Insights), focusing on comparisons between HC and LC groups. More differentially expressed genes (DEG) were seen between the primiparous cows receiving HC versus LC diets than for multiparous cows (597 vs. 497), with only 73 in common, indicating differential dietary responses. Multiparous cows receiving the HC diet had significantly higher circulating glucose and insulin-like growth factor-1 and lower urea than those receiving the LC diet. In response to HC, only the multiparous cows produced more milk. In these animals, bioinformatic analysis indicated expression changes in genes regulating fatty acid metabolism and biosynthesis (e.g., ACACA, ELOVL6, FADS2), increased cholesterol biosynthesis (e.g., CYP7A1, FDPS, HMGCR), downregulation in hepatic AA synthesis (e.g., GPT, GCLC, PSPH, SHMT2), and decreased expression of acute phase proteins (e.g., HP, LBP, SAA2). The primiparous cows on the HC diet also downregulated genes controlling AA metabolism and synthesis (e.g., CTH, GCLC, GOT1, ODC1, SHMT2) but showed higher expression of genes indicative of inflammation (e.g., CCDC80, IL1B, S100A8) and fibrosis (e.g., LOX, LUM, PLOD2). This potentially adverse response to a HC diet in physically immature animals warrants further investigation.

Secreted Colostrum Volume, Transition and Mature Milk Outputs After Calving in Holstein Friesian Cows

Colostrum volume after calving, transition and mature milk outputs in the time from 1^st to 10^th milkings were evaluated at 30 primiparous and 30 multiparous cows milked twice daily. Colostrum volume at the first milking after calving varied from 1.5 to 19.2 kg (mean 9.44 ±5.6 kg SD) in multiparous and from 1.2 to 9.8 kg (mean 5.65 ± 2.3 kg SD) in primiparous cows. Timing of the first milking did not negatively influence colostrum volume. Colostrum volume of the second milking decreased over all multiparous and primiparous cows because the period of time between first and second milking was shorter (10.5 hours). The hourly milk outputs increased sharply from the second to the fourth milking in multiparous and primiparous Holstein Friesian cows. Applying a linear regression model we observed a significant large positive relationship between volume of colostrum at first milking and subsequent transition and mature milk outputs from 2^nd to 10^th milkings. A low colostrum volume secreted was identified in multiparous cows, as a results of sorter dry period and in primiparous cows, probably as a result of low secretory capacity of mammary gland. Extended feeding with transition milk can be real health benefits for the newborn calf.

Effects of Calving Body Condition Score on Blood Acid-Base Balance of Primiparous Holstein-Friesian Dairy Cows in a Commercial Dairy Farm: A Case Study.

Simple SummaryThis study assesses the effect of the body condition score (BCS) on productive variables and the acid–base balance in Holstein heifers. For this purpose, two groups were established according to the BCS: a group of 12 animals with an optimal BCS (range 3.25–3.5) and a group of 15 heifers with a BCS higher than 3.5. The study period started one month before calving (BC) and ran until one month after calving (AC). The results showed that the BCS of heifers does not affect milk production in terms of quantity and quality. In addition, the study of acid–base balance variables provides information that contributes additional insights into metabolic changes that can sometimes go unnoticed.The study was carried out on 27 healthy primiparous Holstein heifers (620 ± 50 kg) kept in a commercial dairy herd. The animals were divided into two groups taking into account the body condition score (BCS) index: BCS < 3.5, n = 12; BCS > 3.5 n = 15. The study period started one month before calving (BC), and ran until one month after calving (AC). Venous blood samples were collected 1 month and 1 week BC, and 1 week and 1 month AC. This study had two objectives: (i) to assess whether a higher or lower BCS affected total milk production and its quality; (ii) to assess changes in the internal fluid (venous pH; partial pressure of CO2, ppCO2; bicarbonate; total CO2, TCO2; base excess, BE; electrolytes Na+, K+, Cl−; and anion gap, AG) that occur during this phase depending on the BCS. We can conclude that the BCS at calving does not affect the productive status during lactation, both in terms of the quantity and quality of milk produced. The excess of crude protein (CP) added through the ration in the lactation phase can trigger a tendency to an alkalotic state, in this case compensated by respiratory buffering mechanisms, as reflected by the TCO2. The changes in electrolytes are a reflection of the movement of free water for milk production, where a balance between measurable anions and cations is observed.

Estimation of heritability and genetic correlations between milk yield and linear type traits in primiparous Holstein-Friesian cows

Estimation of genetic variability and genetic correlations between production traits (milk yield, fat yield, fat content, protein yield, and protein content) and selected type traits (angularity, fore udder height, rear udder height, front teat placement, teat length, and udder depth) was done using data sets of 10,860 first-calving Holstein-Friesian cows raised in the territory of the Republic of Serbia. Genetic variance and covariance were obtained using the Restricted Maximum Likelihood (REML) method, VCE v6 software, and the multi-trait mixed [...]

Genetic parameters of the type traits of Holstein-Friesian primiparous dairy cows

The aim of this study was to determine the level and variability of type traits in primiparous Holstein-Friesian cows, as well as to assess the additive genetic variance of type traits and heritability coefficients. The research was conducted on a data set of linearly evaluated primiparous Holstein-Friesian cows, which is ceded by the Main dairy cattle breed organization in the Province of Vojvodina, which is a unit of the Department of Animal Science, at the Faculty of Agriculture in Novi Sad. Data of 24226 primiparous Holstein-Friesian cows, refer to the period 2012-2015, were analysed. The phenotypic variability of the type traits, as well as effects of systemic factors affecting these traits, were analyzed using standard statistical methods in the Statistica software 13.2, and the general linear model (GLM). A Statistically highly significant effect for most of the type traits had the farm size, interaction of the year and the season of evaluation, age at linear evaluation, lactation stage and a genetic group formed by the year and country of bull/sires birth. The total type traits score (final score), which represents an evaluation of the overall primiparous cow exterior, is calculated for the 24226 linearly evaluated primiparous cows. Estimation of variance components and heritability coefficient calculation is done in the software package WOMBAT. Heritability coefficient values for the primiparous cow's type traits in the Province of Vojvodina were low to middle, ranged from 0.08 for the rear legs - side view up to 0.38 for the stature. Due to the fact that the value of the heritability coefficient depends on the variability of the traits and previous selection, lower heritability may be a consequence of the low genetic variability, or, a higher degree of variability which is a consequence of the effect of the systematic factors. Heritability coefficients indicate a genetic variability of the type traits, and its evaluation is important for the breeding value estimation for the type traits.

Phenotypic characteristics of linear traits of udder and angularity in Holstein-Friesian cows and their correlation with milk yield traits

Data set including 10860 primiparous Holstein-Friesian breed cows first calved in the period from 2011 to 2015, was used in determining phenotypic variability and correlation between the traits of milk yield and linearly estimated traits of udder and angularity. The average values obtained for type traits (angularity, fore udder attachment, front teats placement, teats length, udder depth and rear udder height) were 6.47; 5.74; 4.96; 5.20; 5.99 and 6.25, respectively. The values obtained for phenotypic correlations between linear type traits and traits of milk yield ranged from -0.042 (udder depth and milk yield) to 0.335 (fore udder attachment and protein yield). Positive phenotypic correlation (0.293) was recorded also between fore udder attachment and milk yield which is deemed the most important trait of milk yield while the lowest correlation between milk yields was determined in relation to udder depth (-0.033). The results obtained indicate a possibility of applying direct and indirect multiple traits selection which should be conducted within a national progeny-testing programme on Holstein-Friesian bulls by using the method of selection indexes.

Thyroid hormone profiles and TSH evaluation during early pregnancy and the transition period in dairy cows

The thyroid hormone axis is one important endocrine system within a complex system of various factors and hormones necessary to establish and maintain pregnancy in cattle and in metabolic adaptations towards lactation. Pregnancy and lactation occur contemporaneously in dairy cows, and have major impacts on thyroid hormones as well as status of the hypothalamus-pituitary thyroid axis influences pregnancy and lactation. As especially the thyroid hormone axis with special focus to TSH is not well studies in the past, the aim of the study was to examine the thyroid hormone axis, especially in heifers during adaptation to the first lactation, to verify the association between lactation and thyroid hormones. Secondly, the early pregnancy period was the focus of the present investigation. To determine thyroid hormone patterns and especially thyroid-stimulating hormone (TSH) during the transition period, 12 primiparous Holstein Friesian cows and 41 pregnant and 34 non-pregnant pluriparous cows were sampled. During the transition period, thyroxin (T4) concentrations decreased after calving in primiparous cows, and the milk yield [kg] was negatively correlated with triiodothyronine (T3) and T4 concentrations. In pregnant and non-pregnant pluriparous cows, T3, T4, TSH and free T4 (fT4) decreased between the day of ovulation (day 0) and day 18. From day 18 of gestation to day 100 after AI, an increase in TSH and fT4 and a decrease in Reverse T3 (rT3) was observed in the pregnant cows. In conclusion, the results of the present study confirm that regulative processes within the thyroid hormone metabolism occur during early lactation. For the first time it could be shown in dairy cows that TSH and fT4 increased during early pregnancy whereas rT3 decreased indicating also in bovine species a TSH stimulatory effect by pregnancy.

Estimating economic and production losses in relation to locomotion score in primiparous Polish Holstein-Friesian cows

ABSTRACTThe aim of the study was to determine the effect of the free approach to automatic milking system of primiparous (PP) Holstein-Friesian cows with varying locomotion score on the milking frequency, yield per milking and daily milk yield in the subsequent phases of lactation, and the consequent production and economical losses. The evaluation of cows’ locomotion was successively repeated in seven consecutive months, using a five-point scale of posture and movement assessment. It has been found that in the case of analysed PP cows with the locomotion score 4 led to reduction in the milk production by 11% in third stage of lactation compared to the healthy PP. PP cows with locomotion score 4 less frequent went to milking robot and was characterized by the lowest daily milk production.

Concentrate supplementation of a diet based on medium-quality grass silage for 4 weeks prepartum: Effects on cow performance, health, metabolic status, and immune function

Because negative energy balance (EB) contributes to transition-period immune dysfunction in dairy cows, dietary management strategies should aim to minimize negative EB during this time. Prepartum diets that oversupply energy may exacerbate negative EB in early lactation, with detrimental effects on immune function. However, with lower body condition score (BCS) cows, it has been shown that offering concentrates in addition to a grass silage-based diet when confined during an 8-wk dry period resulted in increased neutrophil function in early lactation. The aim of this study was to examine if similar benefits occur when concentrate feeding was restricted to a 4-wk period prepartum. Twenty-six multiparous and 22 primiparous Holstein-Friesian cows were offered ad libitum access to medium-quality grass silage until 28 d before their predicted calving dates (actual mean of 32 d prepartum; standard deviation = 6.4). At this time multiparous cows had a mean BCS of 2.9 (standard deviation = 0.12) and primiparous cows a mean BCS of 3.0 (standard deviation = 0.14) on a 1 to 5 scale. Cows were then allocated in a balanced manner to 1 of 2 treatments (13 multiparous cows and 11 primiparous cows on each treatment): silage only (SO) or silage plus concentrates (S+C) until calving. Cows on SO were offered the same grass silage ad libitum. Cows on S+C were offered an ad libitum mixed ration of the same grass silage and additional concentrates in a 60:40 dry matter (DM) ratio, which provided a mean concentrate DM intake (DMI) of 4.5 kg/cow per d. After calving, all cows were offered a common mixed ration (grass silage and concentrates, 40:60 DM ratio) for 70 d postpartum. Offering concentrates in addition to grass silage during the 4 wk prepartum increased prepartum DMI (12.0 versus 10.1 kg/cow per d), EB (+40.0 versus +10.6 MJ/cow per d), and body weight (BW; 640 versus 628 kg), and tended to increase BCS (3.02 versus 2.97). However, postpartum DMI, milk yield, milk composition, BW change, BCS change, serum nonesterified fatty acid, and β-hydroxybutryrate concentrations, health, and corpus luteum measures were unaffected by treatment. The in vitro assays of neutrophil phagocytosis, neutrophil oxidative burst, and interferon gamma production, conducted on blood samples obtained at d 14 prepartum and d 3, 7, 14, and 21 postpartum, were unaffected by treatment. Primiparous cows had higher phagocytic fluorescence intensity at d 14 prepartum and d 3 and 7 postpartum; a higher percentage of neutrophils undergoing oxidative burst at d 3, 7, and 21 postpartum; and a higher oxidative burst fluorescence intensity at d 14 prepartum and d 7, 14, and 21 postpartum compared with multiparous cows. This suggests that neutrophil function of primiparous cows was less sensitive to the changes occurring during the transition period than that of multiparous cows. In conclusion, offering concentrates during the 4-wk period prepartum had no effect on postpartum DMI, milk yield, body tissue mobilization, EB, measures of neutrophil or lymphocyte function, health, or corpus luteum activity.

Cytological quality of milk of primiparous cows kept in cubicles bedded with separated manure

Abstract. A study was conducted on the effect of separated manure as bedding material on milk quality as manifested in the somatic cell count. Cows were maintained in a loose barn in cubicles bedded with fresh separated cattle manure (SCM) with 40 % solids content. Analyses were conducted on 242 primiparous Polish Black and White Holstein-Friesian cows in the course of a 305-day lactation. Mean milk yield in that period amounted to over 9000 kg per cow. Somatic cell counts, daily milk yields and chemical composition of milk were analysed. Data were obtained from analyses of 2324 milk samples. It was found that 93.3 % of samples contained less than 400 000 somatic cells per 1 mL milk. Approximately 4.3 % of milk samples contained the number of somatic cells indicating subclinical mastitis (200 000 cells mL−1), while in 2.4 % it was clinical mastitis (&gt; 800 000 cells mL−1). The incidence rate for both forms of mastitis was similar in the beginning and at the end of lactation. Mean daily milk yield of cows producing milk classified according to quality (SCC) grades 1 (&lt; 25 000 cells mL−1) and 2 (&lt; 25 000; 50 000 &gt; cells mL−1) was statistically significantly greater than the yields of other cows. For analysed milk constituents a relationship was found between SCC classes and contents of milk fat and solids. Conducted analyses showed that SCM as bedding in cow cubicles had no effect on somatic cell counts in milk of primiparous cows. The study was conducted in a single holding, in one lactation, on cows calving in 2014.

Associations of high and low milk protein concentrations with energy allocation, milk production, and concentrations of blood plasma metabolites and hormones in Holstein-Friesian cows.

A positive association between milk protein concentration (MPC) and reproductive performance in dairy cows has been shown in several studies globally. This association may positively influence farm productivity and profitability, particularly in seasonally calving, pasture-based herds. However, the differences in milk production and energy allocation, physical characteristics, and blood plasma nutrient status between cows with differing MPC have not been examined, and the underlying mechanisms responsible for the association remain undefined. The objective of this study was to examine associations between MPC and nutrient partitioning in primiparous Holstein-Friesian cows managed under pasture-based dairying conditions, and to identify differences that may indicate the underlying mechanisms. Data were collected from 85 cows at regular intervals during the early part of the 2013 to 2014 seasonal lactation, including daily milk yield, weekly milk composition, weekly body condition score measurements, as well as weekly blood plasma metabolite and hormone concentrations. Cows were retrospectively separated into quartiles based on their average MPC during the first 120d of lactation, and comparisons were made between cows within the highest (high; 3.22 to 3.40%) and the lowest (low; 2.87 to 3.00%) MPC quartiles. The high-MPC cows had lower daily milk yields, yet did not differ in the daily yields of milk solids (protein + fat) compared with the low-MPC cows. After parturition, the high-MPC cows had greater blood plasma concentrations of glucose, insulin, insulin-like growth factor-1 and leptin compared with the low-MPC cows and maintained their body condition score, despite no differences in these variables prepartum. These results indicate an increased partitioning of nutrients toward milk synthesis at the expense of body condition for cows in the low MPC quartile. However, average daily energy outputs in milk were similar in the high- and low-MPC cows. The high-MPC cows calved 12d earlier in the seasonal calving period, reflecting superior reproductive performance when cows in this quartile were 15mo of age. These results suggest that at least part, but not all, of the reported associations between MPC and dairy cow fertility are related to nutrient status during early lactation. Further research is required to understand and use the association.

The effects of varying levels of dietary starch on reproductivetraits in lactating dairy cows

The aim of this study was to determine the effects of three different dietary starch levels on postpartum milk yield, blood metabolites, and reproductive traits in cows. A total of 23 primiparous Holstein-Friesian cows were fed three different diets including different starch levels on a dry matter basis from parturition until day 80. Cows were randomly assigned into the three groups according to the starch levels: low (LS, 16%, n = 7), medium (MS, 20%, n = 8), and high (HS, 24%, n = 8). Milk yields were recorded daily, and body condition score (BCS) was determined every week. Transrectal ultrasonography was performed, and blood samples were taken three times each week to determine reproductive traits and blood metabolites. Although the milk yield was greater in the LS group compared to the other groups, BCS and blood metabolites did not differ among the groups. The postpartum follicular patterns, times of first postpartum ovulation, and involution processes did not differ among the groups. In addition, the ovulatory follicle and corpus luteum sizes and the progesterone levels after induced estrus were numerically greater in HS than other groups. Thus, there were no effects of starch levels on postpartum reproductive traits.

71 CIRCULATING microRNAs AS POTENTIAL BIOMARKERS OF EARLY PREGNANCY IN HIGH-PRODUCING DAIRY COWS

Lactation induces changes in the metabolic status of postpartum dairy cows that negatively affects the likelihood of pregnancy establishment. At present, pregnancy diagnosis with confidence is only possible after the third week of gestation. Earlier diagnosis could facilitate earlier re-breeding, reduce calving intervals, and improve profits for the industry. MicroRNAs (miRNAs) released in body fluids have been identified as minimally invasive biomarkers of several diseases. In addition, distinct miRNA profiles have been directly related to specific stages of human pregnancy. The aim of this study was to profile circulating miRNAs in the blood of high-producing dairy cows in order to identify biomarkers of early pregnancy. In-calf primiparous Holstein-Friesian cows (n = 22) with a similar economic breeding index were used. At calving, cows were randomly assigned to one of two groups: (1) lactating (n = 11; milked twice per day) or (2) non-lactating (n = 11; dried off immediately). Around 65 to 75 days postpartum (dpp), oestrous cycles were synchronized and a single embryo from a superovulated Holstein-Friesian donor was transferred at Day 7 post-oestrus. Plasma samples were analysed at Day 13 (initiation of conceptus elongation) and at Day 19 (initiation of implantation). Pregnancy rate, established by the presence of conceptus at Day 19, was 5/11 (45%) for lactating and 8/11 (73%) for non-lactating cows, respectively. Circulating miRNA levels were profiled in 4 animals per group in non-lactating pregnant, and lactating pregnant and nonpregnant cows at selected timepoints using Illumina HiSEqn 2000 (Illumina Inc., San Diego, CA, USA) for smallRNA sequencing. Annotation and discovery of miRNAs were done using MirDeep2, and read counts were analysed using edgeR to identify differentially expressed miRNAs. Target genes analysis was run with miRWalk and pathways interactions were built using Cytoscape (P ≤ 0.05). Differentially abundant miRNAs between lactating and non-lactating cows were found at both time points (FDR ≤ 0.05). At Day 13, non-lactating cows had a distinct miRNA profile compared with lactating cows showing 8 differentially expressed miRNA (6 v. pregnant and 2 v. nonpregnant cows). At Day 19, no significant differences were found within pregnant cows, but 5 differentially expressed miRNAs were identified between pregnant and nonpregnant cows, regardless of metabolic status. Interestingly, one miRNA, bta-mir140, was up-regulated in non-lactating pregnant cows from Day 13 onwards compared with nonpregnant cows. Furthermore, the same miRNA was up-regulated in lactating pregnant v. nonpregnant at Day 19. Among bta-mir140 target genes, CD274, SLC44A4, CXCL12, and SIRPA were strictly associated with immune tolerance. In conclusion, the maternal plasma miRNome may represent an early indicator of pregnancy status. In particular, the up-regulation of bta-mir140 in pregnant cows suggests that this miRNA may be a good candidate as an early biomarker of fertility. Furthermore, the positive correlation between this miRNA and pathways involved in T-cell response may indicate a role of immune tolerance in preventing rejection at the initiation of implantation.

Effect of dietary supplementation of pasture-based primiparous Holstein-Friesian cows with degummed crude canola oil on body condition score, liveweight, milk yield and composition

The main objective of this study was to investigate the effect of incremental levels of degummed crude canola oil (DCCO) supplementation to pasture-dominant diets of grazing, primiparous, Holstein-Friesian cows on lactation performance, milk composition and liveweight traits. We tested the hypothesis that supplementing primiparous Holstein-Friesian cows with DCCO in a pasture-based dairy system will increase milk yield, fat and protein contents, but decrease cow body condition score (BCS) and liveweight. A random allocation of 20 primiparous Holstein-Friesian cows into four treatments was utilized in an eight-week feeding trial after two weeks of adjustment. The experimental treatments included a wheat-based pellet without DCCO (control), wheat-based pellet with DCCO added at 25 mL/kg on dry matter (DM) basis (low), 35 mL/kg on DM basis (medium) and 50 mL/kg on DM basis (high). Treatment and week (duration) of supplementation were significant sources of variation influencing milk yield (P = 0.0042), fat (P = 0.0118) and protein (P = 0.0002). Cows in the high treatment group had the greatest milk yield (168.7 ± 3.5 kg/week) and lower fat (3.3 ± 0.1%) and protein (3.0 ± 0.09%) percentages than cows in the control group (milk yield of 157.1 ± 3.5 kg/week, 4.0 ± 0.2% fat and 3.1 ± 0.0% protein). With the exception of somatic cell count and yield, the week (duration) of supplementation significantly influenced all milk composition traits. We concluded that supplementation of grazing dairy cows with DCCO had no negative impact on BCS and body weight gain. DCCO can be used to enhance milk yield, but at the expense of milk fat and protein.

Gene Expression Profiles of Aralkylamine N-Acetyltransferase, B-cell Translocation Gene-2 and Fatty Acid Synthase in Pasture-based Primiparous Holstein-Friesian Dairy Cows Supplemented with Crude Degummed Canola Oil

The effect of oil-rich supplements on the expression of genes involved in lipogenesis and reproduction in pasturebased dairy cows is currently unknown, or at best, scanty and limited to impacts on cow liveweight, body condition score, milk composition, fatty acid and plasma metabolite profiles only. This research investigated the gene expression patterns of Aralkylamine N-acetyltransferase (AANAT), B-cell translocation gene-2 (BTG2) and Fatty Acid Synthase (FASN) genes in response to incremental levels of dietary crude degummed canola oil (CDCO). We tested the hypothesis that the relative mRNA abundance and gene expression profiles of AANAT, BTG2 and FASN in primiparous Holstein-Friesian cows will be up-regulated in response to post-partum dietary supplementation with CDCO in a typical pasture-based dairy production system. Thus, the primary objective of this study was to investigate the expression of AANAT, BTG2 and FASN genes in response to incremental levels of CDCO. A random allocation of primiparous Holstein-Friesian dairy cows into four treatment groups comprising wheat-based pelleted with no supplemental CDCO (control), or with CDCO added at 25 ml kg-1 DM (low), 35 ml kg-1 DM (medium) and 50 ml kg-1 DM (high) was utilized in a ten-week experimental feeding trial including two weeks of adjustment. Both level of supplementation and their interaction with duration were significant sources of variation (P 0.05). The high (0.67 fold), medium (0.87 fold) and low (0.56 fold) treatments had suppressed BTG2 expressions compared to the control (1.0 fold) group. The low expression of BTG2 might be important when the reproductive system of cows is recovering from the effect of gestation and new cell growth is required.

Effect of incremental levels of crude degummed canola oil on milk progesterone, plasma luteinizing and follicle stimulating hormones of primiparous Holstein–Friesian cows in a pasture-based system

Dietary supplementation of lactating cows with fat can alter the profiles of key reproductive hormones and boost postpartum energy balance. However, published data under Australian pasture-based dairy production conditions are scanty and inconsistent. Therefore, the objective of this study was to determine whether dietary inclusion of crude degummed canola oil (CDCO) at incremental levels for eight-weeks will have significant influence on progesterone (P4), luteinizing hormone (LH) and follicle stimulating hormone (FSH) of primiparous Holstein–Friesian cows grazing pastures. We tested the hypothesis that postpartum supplementation of primiparous Holstein–Friesian cows with dietary CDCO in a pasture-based system will alter the concentrations of P4, LH and FSH reproductive hormones. A random allocation of twenty primiparous Holstein–Friesian cows into four treatment groups that consisted of a wheat-based pelleted basal diet with no supplemental CDCO (control), or a wheat-based pelleted basal diet with CDCO added at 25ml/kg (low), 35ml/kg (medium) and 50ml/kg (high) was employed in an eight-week feeding trial after two weeks of adjustment. Supplementation levels of CDCO and week of data collection were significant sources of variation (P<0.05) that influenced FSH and P4 concentrations. However, there was no significant effect of supplementation on LH concentration (P>0.05). It was apparent that cows in the high (0.459ng/ml), medium (0.367ng/ml) and low (0.251ng/ml) levels of oil treatments had higher mean plasma FSH concentrations compared to the control (0.172ng/ml) cows. It was concluded that the current levels of CDCO can be used in pasture-based dairy systems to increase FSH, but not LH and P4.

Temperament holštýnsko-frízských krav při dojení v dojírně a jeho vztah k mléčné produkci

The aim of this study was to evaluate the change of temperament of Holstein cows scored before and during milking during the entire lactation and to calculate correlation between temperament measured in the two moments as well as milk production traits and temperament. Observations were carried out on 17 primiparous Holstein Friesian cows starting their lactation within 85 days. Measurements of temperament and milk production traits were taken once in each month of the lactation, during the morning milking, in a milking parlour. Temperament was assessed in a 5-point scale during udder preparation and milking procedure (1: very nervous, 5: very quiet). Data of milk yield and milk flow were collected individually on each test day morning. Results showed changes during the lactation in temperament of cows scored directly before milking (P &lt; 0.01), however, temperament during milking did not alter with months (P &gt; 0.10). By correlation coefficients, behaviour assessed in the two moments cannot be regarded as the same. In addition loose, significant relations were found only between milk traits and temperament before milking.

Effect of crude degummed canola oil and ad libitum grazing on plasma metabolites of primiparous Holstein-Friesian cows in a pasture-based system.

BackgroundThe supplementation of fat to lactating dairy cows has long been used as a management tool to increase dietary energy density for improving cow production, reproduction and to alleviate negative energy balance. Attempts have been made to investigate the effect of canola meal on plasma metabolites in lactating cows, but the results have been diverse and inconsistent. To our current knowledge, there is a dearth of published information on the utilization of Crude Degummed Canola Oil (CDCO) in pasture-based dairy systems. Therefore, the objective of this study was to investigate the changes in plasma metabolite profiles of pasture-based, primiparous, Holstein-Friesian cows supplemented with varying dietary levels of CDCO for eight weeks. The study tested the hypothesis that feeding grazing primiparous Holstein-Friesian cows for eight weeks with incremental levels of CDCO supplement will decrease plasma non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA), but increase plasma cholesterol and glucose metabolites.ResultsTwenty lactating primiparous Holstein-Friesian cows 40 days in milk were randomly allotted into four treatment groups that consisted of a wheat-based, pelleted basal diet with no supplemental CDCO (control), basal diet with CDCO added at 25 ml/kgDM (DM; dry matter) (low), 35 ml/kgDM (medium) and 50 ml/kgDM (high) in an eight-week feeding trial, after two weeks of adjustment. Treatment influenced BHBA but had no effect on plasma NEFA, cholesterol and glucose metabolite profiles (P > 0.05). However, week of supplementation had a significant effect (P < 0.05) on BHBA, NEFA and glucose concentrations.ConclusionsWe concluded that with the exception of BHBA, CDCO at current levels of supplementation does not alter the plasma metabolite profiles of grazing primiparous cows. The lack of significant differences across treatments seems to indicate that higher levels of CDCO than the current levels used in this study, are probably needed. Furthermore, the duration of supplementation with CDCO had a greater impact on plasma metabolites than the levels of supplementation. Our findings also suggest that primiparous cows grazing high quality pastures during spring have sufficient energy intakes to prevent negative energy balance at 40 days in milk without the need for added fat supplements.

Influence of Supplementing Pasture-Based Primiparous Holstein-Friesian Dairy Cows with Crude Degummed Canola Oil on Milk Fatty Acid Composition

The quest for alternative sources of healthy nutrients that facilitate the modification of milk without compromising drinking quality is a continuous research endeavour. The objective of the study was to the milk fatty acid composition of pasture-based primiparous Holstein-Friesian dairy cows with crude canola oil (CDCO) with a view to improving the milk quality for beneficial health effects. This study tested the hypothesis that incremental supplementation of grazing primiparous Holstein-Friesian cows with CDCO will alter milk fatty acid composition towards increased total monounsaturates. Comparisons were made between unsupplemented grazing dairy cows and their peers on dietary supplements containing low (25ml/Kg DM), medium (35ml/Kg DM) or high levels (50ml/kg DM) of CDCO in addition to ad libitum grazing access to . There was no significant effect (p&gt;0.05) of CDCO supplementation for eight weeks the proportions of total polyunsaturated fatty acids (tPUFA), omega-3 (ω-3) and omega-6 (ω-6) fatty acids in milk. However, significant impacts of CDCO observed on the proportions of 18:1ω9c, 18:1ω7t, total saturated (tSFA) and total monounsaturated (tMUFA) fatty acids (p&lt;0.005), with a significant increase in the tMUFA/tSFA ratio in cows consuming CDCO. It was concluded that incremental levels of CDCO supplementation can modify the fatty acid composition of milk towards increased monounsaturates without any negative impact on grazing primiparous cows

Effect of genetic merit for energy balance on luteal activity and subsequent reproductive performance in primiparous Holstein-Friesian cows

Postpartum energy status is critically important to fertility. However, studies dealing with the relationship between both traits are rare and most refer only to the phenotypic level. In this study, random regression models were used to generate cow-specific lactation curves for daily breeding values (BV) of energy balance (EB) to assess the effect of genetic merit for energy status on different traits derived from progesterone profiles and on subsequent reproductive performance of high-producing dairy cows. Individual feed intake, milk yield, and live weight were recorded for lactationd 11 to 180, and EB was estimated on a daily basis. The results provided the basis for the estimation of BV for 824 primiparous Holstein-Friesian cows. For a subset of these cows (n=334), progesterone profiles for the resumption of ovarian activity were available. Four different traits describing the genetic merit for EB were defined to evaluate their relationship with fertility. Two EB traits referred to the period in which the average daily EB across all cows was negative (d 11 to 55 postpartum), and 2 parameters were designed considering only daily BV for d 11 to 180 in lactation that were negative. We found that cows with a high genetic merit for EB had a significantly earlier resumption of ovarian activity postpartum. Thus, an EB (indicator) trait should be included in future breeding programs to reduce the currently prolonged anovulatory intervals after parturition.