Lactating Dairy Cows Research Articles

The effects of feeding liquid or pelleted formulations of Asparagopsis armata to lactating dairy cows on methane production, dry matter intake, milk production and milk composition

Asparagopsis armata has been reported to have strong antimethanogenic effects when fed to dairy cows. The aim of this study was to evaluate the effect of a liquid and a pelleted formulation of A. armata when fed to lactating dairy cows as a supplemental feed twice daily at milking on i) enteric methane emissions, milk yield and dry matter intake (DMI), and ii) presence of halogenated compounds in milk, urine, faeces, and blood. Forty lactating, multiparous, Holstein-Friesian cows (117 ± 20.2 days in milk) were randomly allocated one of four treatments; 1) CON1: basal diet plus liquid supplement without A. armata, 2) AA1: basal diet plus liquid supplement with A. armata, 3) CON2: basal diet plus pellet supplement without A. armata, and 4) AA2: basal diet plus pellet supplement with A. armata. The liquid and pelleted supplements were offered twice daily for 34 days. Supplements were offered with a grain mix during each milking. The basal diet consisted of vetch hay ad libitum and 6.15 kg dry matter (DM)/d of a grain mix fed as 3.07 kg DM in the dairy per milking. Cows given the AA1 treatment received 298 mg bromoform per day while cows on the AA2 treatment received 293 mg bromoform per day. Individual forage DMI were measured daily via electronic monitoring of individual cows at the feed bins. Methane emissions were measured using the modified sulphur hexafluoride tracer technique on the last 5 days of the experiment. Feeding the A. armata formulations showed no effect on total DMI, forage DMI, concentrate DMI or milk yield. Methane production (g CH4/d), methane yield (g CH4/kg DMI) and methane intensity (g CH4/kg energy corrected milk) were reduced by about 20 % for both the liquid and the pelleted A. armata formulations. Feeding the A. armata formulations led to increased bromoform concentrations in milk (∼2.0 µg/L) but were well below the limit for safe consumption (100 µg/L). It is concluded that both formulations were effective in reducing enteric methane emissions and that milk from cows fed these A. armata formulations is safe for human consumption.

Ceramide on the road to insulin resistance and immunometabolic disorders in transition dairy cows: driver or passenger?

Dairy cows must undergo profound metabolic and endocrine adaptations during their transition period to meet the nutrient requirements of the developing fetus, parturition, and the onset of lactation. Insulin resistance in extrahepatic tissues is a critical component of homeorhetic adaptations in periparturient dairy cows. However, due to increased energy demands at calving that are not followed by a concomitant increase in dry matter intake, body stores are mobilized, and the risk of metabolic disorders dramatically increases. Sphingolipid ceramides involved in multiple vital biological processes, such as proliferation, differentiation, apoptosis, and inflammation. Three typical pathways generate ceramide, and many factors contribute to its production as part of the cell's stress response. Based on lipidomic profiling, there has generally been an association between increased ceramide content and various disease outcomes in rodents. Emerging evidence shows that ceramides might play crucial roles in the adaptive metabolic alterations accompanying the initiation of lactation in dairy cows. A series of studies also revealed a negative association between circulating ceramides and systemic insulin sensitivity in dairy cows experiencing severe negative energy balance. Whether ceramide acts as a driver or passenger in the metabolic stress of periparturient dairy cows is an unknown but exciting topic. In the present review, we discuss the potential roles of ceramides in various metabolic dysfunctions and the impacts of their perturbations. We also discuss how this novel class of bioactive sphingolipids has drawn interest in extrahepatic tissue insulin resistance and immunometabolic disorders in transition dairy cows. We also discuss the possible use of ceramide as a new biomarker for predicting metabolic diseases in cows and highlight the remaining problems.

Effects of heating soybeans on postruminal amino acid bioavailability, performance, and ruminal fermentation in lactating cows.

Soybeans can provide ruminally degradable protein, lipid, and metabolizable amino acid (AA) to lactating dairy cows; however, soy-based trypsin inhibitors can limit protein digestion in nonruminants. Eight ruminally cannulated lactating Holstein cows were used to evaluate the impacts of soy-based trypsin inhibitors on nutrient disappearance, lactation, and plasma AA bioavailability. Treatments were abomasal infusion of 0 or 400g/d casein or a crystalline AA analog of casein with unroasted or roasted soybeans fed at 10% dry matter (DM). Data were analyzed using the MIXED procedure of SAS. Measures of digestion were determined from fecal output determined with acid detergent insoluble ash and urine output determined from measures of urine creatinine. Neither soybean processing (P ≥ 0.20) nor the source of abomasal infusion (P ≥ 0.60) impacted nutrient digestibility. Ruminal ammonia, isobutyrate, and isovalerate were increased (P ≤ 0.01) among cattle consuming unroasted soybeans. Source of infusion did not affect (P ≥ 0.38) ruminal volatile fatty acids or nitrogen metabolism. Ruminal N metabolism was largely unaffected by soybean processing although microbial N efficiency was greater (P < 0.01) among cows fed unroasted soybeans. DM intake and energy-corrected milk were greater (P < 0.01) in cows fed roasted compared to unroasted soybeans. The proportion of fat, protein, lactose, and solids not fat (SNF) in milk did not differ between soybean processing or postruminal AA source, but fat, protein, lactose, and SNF yield was greater (P ≤ 0.01) when cows were fed roasted soybeans because milk yields were greater when cows were fed roasted vs. unroasted soybeans. As expected, infusion of casein or its crystalline AA analog increased plasma essential AA and milk urea nitrogen concentration. The rate of increase in essential AA concentration in plasma was 2.9× greater for casein than for crystalline AA. These data seem to indicate that soy-based trypsin inhibitors have no impacts on postruminal AA bioavailability when fed to cows and that metabolizable protein from casein is greater than from crystalline AA.

Effects of feeding an inoculated corn silage with or without a direct-fed microbial on dry matter intake, milk production, and nutrient digestibility of high-producing lactating Holstein cows.

This study evaluated the effects of inoculating corn silage and/or feeding a direct-fed microbial (PRO) on performance and nutrient digestibility of lactating dairy cows. At harvesting, corn silage was treated either with water (culated or not [CON]) or Lactococcus lactis and Lentilactobacillus buchneri (INC; SiloSolve FC) at 1.5 × 105 cfu/g of corn silage. Ten mini silos and one farm-scale silo bunker per treatment were prepared for the laboratory and the lactating dairy cow trial, respectively. Five mini silos per treatment were opened on days 2 or 90 post-ensiling for pH measurement, as well as chemical analysis and aerobic stability, respectively. The farm-scale silo bunkers were opened 77 d post-ensiling for the beginning of the lactating cow trial. Eighty lactating Holstein cows were assigned in a 2 × 2 factorial design to: (1) CON silage without PRO (CON-CON; n = 20), (2) CON silage with PRO at 14g/head/d (CON-PRO; n = 20), (3) INC silage without PRO (INC-CON; n = 20), and (4) INC silage with PRO at 14g/head/d (INC-PRO; n = 20). Concurrently with the feeding trial, eight cows per treatment were chosen for nutrient digestibility. The pH of the corn silage was not affected by the silage inoculant (P ≥ 0.29), but INC yielded greater concentration of acetic acid and longer aerobic stability (P < 0.01). Dairy cows fed INC had a lower mean total dry matter intake (DMI), milk protein content, and somatic cell counts vs. CON (P ≤ 0.02). On the other hand, milk and fat- and protein-corrected milk (FPCM) production efficiency, milk urea-N, DM, crude protein, and starch digestibility were greater for INC-fed cows (P ≤ 0.03). Feeding direct-fed microbials (DFM) improved mean body weight, milk yield, and FPCM, as well as milk protein and lactose yield (P ≤ 0.05), but reduced milk fat and protein content (P = 0.02). A silage inoculant × DFM interaction was observed for milk production efficiency, milk protein and lactose content, and somatic cell count (P ≤ 0.05). Dairy cows fed INC-CON had a greater milk production efficiency and milk lactose content (P ≤ 0.04), but INC-PRO had lower milk protein content and SCC (P ≤ 0.03). In summary, inoculating L. lactis and L. buchneri increased acetic acid content and aerobic stability of corn silage, reduced DMI, but improved milk production efficiency and nutrient digestibility of lactating Holstein dairy cows. On the other hand, feeding PRO improved milk, protein, and lactose yield. Additionally, combining the feeding of an inoculated corn silage with PRO reduced milk somatic cell count.

Using a multi-omics approach to explore potential associations with rumen content and serum of cows with different milk production levels based on genomic predicted transmitting ability for milk and phenotypic milk production.

This study aims to compare rumen microbiome and metabolites between second lactation dairy cows in the 75th percentile (n = 12; 57.2 ± 5.08 kg/d) of production according to genomic predicted transmitting ability for milk (GPTAM) and their counterparts in the 25th percentile (n = 12; 47.2 ± 8.61 kg/d). It was hypothesized that the metagenome and metabolome would differ between production levels. Cows were matched by days in milk (DIM), sire, occurrence of disease, and days open in previous lactation. For an additional comparison, the cows were also divided by phenotype into high (n = 6; 61.3 ± 2.8 kg/d), medium (n = 10; 55 ± 1.2 kg/d), and low (n = 8; 41.9 ± 5.6 kg/d) based on their milk production. Samples were collected 65 ± 14 DIM. Rumen content was collected using an oro-gastric tube and serum samples were collected from the coccygeal vessels. High-resolution liquid chromatography-mass spectrometry (LC-MS) was used for rumen and serum metabolite profiling. Shotgun metagenomics was used for rumen microbiome profiling. Microbiome sample richness and diversity were used to determine alpha and Bray-Curtis dissimilarity index was used to estimate beta diversity. Differences in metabolites were determined using t-tests or ANOVA. Pearson correlations were used to consider associations between serum metabolites and milk production. There was no evidence of a difference in rumen metabolites or microbial communities by GPTAM or phenotype. Cows in the phenotypic low group had greater serum acetate to propionate ratio and acetate proportion compared to the cows in the phenotypic medium group. Likewise, serum propionate proportion was greater in the medium compared to the low phenotypic group. Serum acetate, butyrate, and propionate concentrations had a weak positive correlation with milk production. When investigating associations between rumen environment and milk production, future studies must consider the impact of the ruminal epithelium absorption and post-absorption processes in relation to milk production.

The role of endoplasmic reticulum stress in metabolic diseases and mammary epithelial cell homeostasis in dairy cows.

High-yielding dairy cows undergo various physiological stresses during the transitional phase of the calving cycle. In this period, they experience negative energy balance, subjecting the liver to significant metabolic stress from an influx of nonesterified fatty acids. This metabolic stress not only impairs liver function but also diminishes milk production. Early lactation dairy cows may develop endoplasmic reticulum (ER) stress in the liver, potentially leading to liver-related diseases and contributing to ER stress in mammary epithelial cells, resulting in decreased milk production. Natural products that alleviate ER stress have been identified, and if further in vivo studies confirm their efficacy, they have potential as feed additives to prevent disease and reduce milk yield. Conversely, physiological levels of ER stress play a role in mammary gland development and positively influence protein synthesis in milk. Understanding the threshold level of ER stress in mammary tissue and its detailed mechanisms will be crucial in dairy farming.

Productive Performance of Lactating Crossbred Dairy Cows Fed with Wheat Straw‐Based Densified Complete Feed Block

The experiment was designed to determine the effect of feeding densified complete feed block (DCFB) on the production performances of lactating F1 Friesian x Borena crossbred cows. Four mid‐lactating multiparous cows with 2–5 parity having similar milk yield (8–10 l·day−1) were evaluated using 4 × 4 Latin square design for a total of 84 days. The treatments include natural pasture hay supplemented with a concentrate mixture at the rate of 0.5 kg·l−1 of milk yield·cow−1 (T1) and three different wheat straw‐based DCFBs in the ratio of 50 : 50 (T2), 40 : 60 (T3), and 30 : 70 (T4). The result revealed that the average daily dry matter (DM) intake was similar among all dietary treatments except for T2 that had lower (P &lt; 0.05) daily DM intake. The crude protein (CP) and organic matter (OM) intakes for cows in T3 and T4 were comparable (P &gt; 0.05) but significantly higher (P &lt; 0.05) compared to T1 and T2. The neutral detergent fiber (NDF) intake remained the same among treatment groups while T1 consumed higher (P &lt; 0.05) acid detergent fiber (ADF) compared to other diets. Cows in T3 and T4 groups had higher (P &lt; 0.05) DM and OM digestibility but comparable (P &gt; 0.05) NDF and ADF digestibility compared to T1. The CP digestibility and daily average milk yield were higher (P &lt; 0.05) for T4. Daily fat, protein, and lactose yield in the DCFB group showed an increasing trend with the level of concentrate, whereas cows in the T4 group exceptionally produced higher (P &lt; 0.05) yields. Fat‐corrected milk yield (FCM) was lower (P &lt; 0.05) for T4 compared to T1 and T2 groups. Milk fat percentages were lower (P &lt; 0.05) but milk protein percentages were higher for cows in T4 but similar for the rest of the diets. Milk lactose did not vary (P &gt; 0.05) over all the treatments. Milk conversion efficiency was similar (P &gt; 0.05) among the DCFB but higher (P &lt; 0.05) for control cows. The partial budget analysis indicated that net profit and marginal return were much higher for diet in the ratio of 40 : 60. Inclusion of wheat straw at 40% could be an efficient feeding option for F1 Friesian x Borena lactating crossbred cows managed under indoor conditions. However, DCFB manufacturing and distribution at a large scale requires machineries (chopper/grinder, mixer, and compressor). Further study needs to evaluate the storability and strength of the DCFBs under varying storage conditions and the long‐term effect of DCFB on milk yield and quality of improved lactating dairy cows in Ethiopia.

Impact of presynchronization and Ovsynch on early postpartum ovarian activity and fertility of dairy cows in Libya.

Reproductive efficiency affects dairy cow profitability. Ovarian function in postpartum (P.P.) has been better understood using ultrasound and hormonal assays. Optimizing ovulation synchronization and carefully timing artificial insemination (TAI) can greatly enhance reproductive rates in dairy cows. This experiment was designed to investigate the reproductive performance and ovarian activity in early postpartum lactating dairy cows using the Presynch-PGF2α, Ovsynch protocol, and TAI. Randomly the cows were assigned to a control group and a treatment group, based on the chronological order of their calving date. On day 14 P.P., both groups received two cloprostenol treatments, 14 days apart. Ultrasonographic inspections were conducted on day 14 to check ovarian activity and uterine contents. On day 11, after presynchronization, cows in the treatment group were given 100 µg IM. of cystorelin, followed by a luteolytic dose of 500 µg IM., cloprostenol on day 7, and a second dose of cystorelin on day 8 (36 hours later). After the second cystorelin injection by 16-20 hours, cows were inseminated, while the control group had all cows displaying spontaneous estrus between day 0 and day 28 were artificially inseminated. Ovarian activity began to improve at 82.61% on day 19 P.P., with complete recovery between days 24 and 27 P.P. The second cloprostenol injection approached, causing follicular size to reach 8.41 ± 1.04 mm. After the second injection, ovarian activity switched from follicular to luteal, with corpus luteum rates of 23.91% and 26.1%. The presynchronized PGF2α regimen significantly enhanced ovarian activity from days 19-35 P.P. Ovulation and pregnancy rates in the Ovsynch group were 54.2% and 41.7% at the first timed artificial insemination (TAI), compared to 54.5% and 31.8% in the control group. There was no significant impact between them; it was just high in the presynchronized Ovsynch group. However, the P.P. period was minimized to 47-49 days till the first AI reached a 41.7% pregnancy rate and 20.8% at the second AI, for an overall 62.5%. The current study concludes that presynchronization during preservice in clinically normal P.P. dairy cows reduces P.P. duration, increases ovarian activity performance, and reduces ovarian dysfunctions from day 19 to day 35 P.P., as well as improves the pregnancy rate.

Effect of Dietary Source of Omega-3 Fatty Acids on Milk Production, Fatty Acid Profiles and IGF-1 of Lactating Dairy Cows in Arid Subtropics

Effect of Dietary Source of Omega-3 Fatty Acids on Milk Production, Fatty Acid Profiles and IGF-1 of Lactating Dairy Cows in Arid Subtropics

Cactus Cladodes and Sugarcane Bagasse Can Partially Replace Earless Corn Silage in Diets of Lactating Dairy Cows

This study aimed to evaluate the effects of replacing earless corn silage (ECS) with cactus cladodes (CC; Opuntia spp.) and sugarcane bagasse (SB) on nutrient intake, digestibility, feeding behavior, milk yield (MY), and composition of lactating dairy cows. Ten Holstein cows, weighing 571 ± 97.0 kg and producing 23.0 ± 4.4 kg of milk per day, were assigned to two contemporaneous 5 × 5 Latin squares. Treatments consisted of five levels of ECS replacement with CC plus SB (0, 25, 50, 75, and 100%). The results showed a linear increase in dry matter (DM) intake (p &lt; 0.05) (15.98 and 18.73 kg/day) and a quadratic increase (p &lt; 0.05) in crude protein and energy intake (2.97 kg/day and 27.52 Mcal/day at 95.4 and 88.6% substitution, respectively). Apparent DM digestibility increased (p &lt; 0.05), but fiber digestibility decreased linearly (p &lt; 0.05). Treatments had a quadratic effect (p &lt; 0.05) on MY and fat-corrected MY (24.17 kg/day and 21.9 kg/day at 63.9% and 38.6% CC plus SB, respectively). Milk fat (3.26 and 2.35%) and total solids content decreased linearly (p &lt; 0.05), whereas the percentages of protein, lactose, and nonfat solids increased (p &lt; 0.05). Additionally, the CC–SB diets linearly reduced the time spent on feeding and rumination and total chewing time. For Holstein cows fed common semiarid diets, milk production can be maximized by replacing 38.6% of ECS with CC plus SB.

Management practices and cow comfort of crossbred dairy cows in youth managed dairy farm enterprises, South Gondar Zone, Amhara Region, Ethiopia

Good dairy farming methods and cow comfort are essential variables in reproductive efficiency, milk output, milk quality, and dairy cow health. The purpose of this study was to look into the management techniques and cow comfort status of crossbred dairy cows in youth managed dairy farm enterprises in Ethiopia's Amhara region's South Gondar zone. All (20) youth-managed dairy farm enterprises were chosen and questioned using a pre-tested semi-structured questionnaire, and all (204) lactation dairy cows were chosen for cow comfort assessment. The SPSS version 22 program was used to analyze the data. According to the findings, the most common feed sources used for their dairy cattle were formulated and unformulated agro-industrial byproducts followed by non-conventional and hay. Piped (35%) and bore (30%) water were the most common water sources for dairy cattle, with the majority of farms allowing free access to water. The majority of dairy farm firms (70%) uses artificial insemination as well as bull services. The majority of dairy farm enterprises (55%) had shared sheds, followed by individual sheds (45%) built with government assistance (55%), and family (30%) with the same design and construction. The challenges confronting dairy farm enterprises were ranked feed scarcity and high feed costs first, followed by a lack of access to land, a lack of access to markets, and a lack of credit, whereas the opportunities for dairy farm enterprises were ranked first increased demand for milk and milk products first, followed by rapid urbanization, rapid population growth, and the availability of cheap labor. The vast majority of cows (92%) were severely lame, followed by moderate lameness (83%) and the vast majority of cows (52.5%) had moderately injured legs, followed by severely injured legs. The udder and leg cleanliness of most cows was mid cleanliness (52.7%), as opposed to dirty (30%) and clean (17.2%) with a low cow comfort index (0.48). The mean stall length, bed length, brisket board height, neck rail height, lung space, feeder height, and feeder width were 239±16 cm, 222.7±28.3 cm, 10.5±3.6cm, 61.5±15.3 cm, 128.15±21.5 cm, 40.6±8.7 cm, and 36.7±6.9 cm, respectively. The results also revealed that the overall floor softness scored marginal (45%) softness rather than hard (30%) and normal (25%) floor softness. The majority of dairy farm enterprises (55%) did not provide bedding material for their cows and, the bedding materials include straw, hay, and sawdust. Bedding materials are renewed once a month (37.5%), twice a week (37.5%), and once a week (25%). The frequency of manure removal was twice daily (60%), three times daily (30%), and once daily (20%). The findings revealed that the cow’s comfort status is poor, so it is recommended that the barn be renovated routine management practices be improved, and assistance from the government and other relevant stakeholders is required in order to obtain credit to renovate the cow barn and improve management practices.

Dose effect of Actisaf Sc 47 yeast probiotic (Saccharomyces cerevisiae) supplementation on production, reproduction, and negative energy balance in early lactation dairy cows.

The study evaluated the dose effect of dietary supplementation with yeast probiotic Saccharomyces cerevisiae (CNCM I-4407, 1010 CFU/g, Actisaf Sc 47; Phileo by Lesaffre, France) on production, energy metabolism, and reproduction in lactating dairy cows. About 117 multiparous Holstein cows from 3 to 60 d in milk held in a barn with an automatic milking system were enrolled in a randomized complete block design and blocked according to calving day, parity, and previous milk yield. The cows were assigned to a basal diet (15% CP, 22% starch) plus either 5g (Y5 group, n = 39), 10g (Y10 group, n = 39), or 0g (CON, n = 39) of yeast probiotic, presented on top of concentrate fed in the robot. Milk yield and body weight were recorded daily, milk composition, and somatic cell count (SSC) every 2wk, and body condition score (BCS) was estimated at days -14, 14, and 40 post-calving. Data were analyzed using a linear mixed model. The Y10 group showed an increased average daily yield of energy-corrected milk (ECM) over CON (+3.5kg, P < 0.05) and Y5 (+0.8kg). There were no significant differences between the groups in milk fat, milk protein, milk SCC linear score, milk urea, blood beta-hydroxy-butyric acid levels, and BCS. Body weight loss from 3 to 90 d in milk was numerically lower (13.8kg) in Y5 than in CON (25.3kg), and the success rate from the first insemination was the highest in YP5 and YP10 groups (39%) than in Control (26%). The yeast probiotic supplementation to early lactation high-producing dairy cows showed a clear effect of the high dose (10g) on ECM milk production, although the lower dose (5g) showed only numerical ECM production increase, both doses displayed better use of energy from the diet than the control and suggest a better resource efficiency.

Residual methane emissions in grazing lactating dairy cows

ABSTRACT Residual methane emission (RME) is a trait that has previously been identified as being independent of animal production traits. The objective of this study was to investigate the effect of ranking grazing dairy cows by RME on animal productivity and enteric methane (CH4) emissions. Milk production, dry matter intake (DMI), liveweight (LWT) and CH4 were recorded on grazing late lactation dairy cows at Teagasc Moorepark, Ireland. The dairy cows were producing 352 g CH4/day, while consuming 16.6 kg DM. The mean methane yield was 20.79 g CH4/kg DMI. Residual methane emission was calculated as the difference between measured CH4 yield and New Zealand emission factor (21.6 g CH4/kg DMI). These dairy cows were ranked based on their RME and classified into groups. The low RME group produced 15% less CH4 than the high RME group while maintaining milk production and feed conversion efficiency. The low RME group had lower methane yield, and methane intensity. There are no significant phenotypic correlations between RME and animal production traits such as energy corrected milk yield, or LWT. These results indicate that RME has the ability to select and rank low emitting grazing dairy cows while being independent from animal productivity traits.

Sütçü sığırlarda klinik ve subklinik ketozis ile ilişkili üreme performansı, süt verim parametreleri ve bazı postpartum hastalıklar

Negative energy balance (NEB) is a physiological state that arises during the transition from pregnancy to lactation in dairy cows. This transition period is associated with a decline in dry matter intake and an increased demand for energy sources for milk production. Ketosis, a metabolic disorder, often emerges shortly after calving and is characterized by reduced glucose levels, depleted liver glycogen, and elevated ketone body concentrations. The study aimed to investigate the impacts of ketosis on milk yield, reproductive parameters, and postpartum metabolic diseases in cows with subclinical and clinical ketosis. The study involved 267 healthy pregnant Holstein dairy cows in the second and third lactation periods. Groups were formed based on postpartum third-day beta-hydroxybutyrate (BHBA) levels. The groups included control (BHBA &lt; 1.2 mmol/dL), subclinical ketosis (BHBA = 1.2-2.4 mmol/dL), and clinical ketosis (BHBA &gt; 2.4 mmol/dL) groups. Results indicated that higher body condition scores (BCS) during calving were associated with an increased risk of postpartum ketosis (p

Profil Diferensiasi Leukosit dan Biomarker Stress Sapi Perah Laktasi dengan Pemberian Feed Supplement di Kelompok Ternak Tunas Mekar KSU Tandangsari

This research was conducted from April to June 2023 at the Tunas Mekar Cattle Group, KSU Tandangsari. As many as 16 Friesian Holstein (FH) dairy cows lactating 1-5, were used in this study to review the leukocyte differentiation and biomarker stress profiles and find out which treatment had the best effect on the leukocyte differentiation profile and biomarker stress. The study used a completely randomized design (CRD) consisting of 4 treatments and 4 replications. The treatments included P0 (control) consisting of 60% forage + 40% concentrate; P1 = 60% forage + 40% concentrate (97% concentrate + 3% protein by-pass); P2 = 60% forage + 40% concentrate (95% concentrate + 3% protein by-pass + 2% Ca-PUFA); and P3 = 60% forage + 40% concentrate (93% concentrate + 3% protein by-pass + 2% Ca-PUFA + 2% organic minerals). Based on the results of the study, it was shown that feeding supplementation had a significant effect (P&lt;0.05) on the leukocyte differentiation profile and stress biomarkers of lactating dairy cattle in the Mekar Tunas Livestock Group, KSU Tandangsari. Lactation dairy cows treated with P3 = 60% forage + 40% concentrate (93% concentrate + 3% protein by-pass + 2% Ca-PUFA + 2% organic minerals) had lower mean leukocyte differentiation and biomarker stress than controls ( P&lt;0.05). This can be interpreted that the provision of rations supplemented with feed supplements in the form of 3% protein by-pass + 2% Ca-PUFA + 2% organic minerals is able to reduce the level of heat stress as seen based on leukocyte levels and their differentiation and stress marker enzymes in the blood.

Use of milk haptoglobin concentration as an indicator in animal health monitoring of dairy cows

The aim of the present study was to investigate relationships between elevated haptoglobin concentrations in milk and clinical as well as laboratory parameters in early lactating dairy cows. Furthermore, cut-off values should be identified for the differentiation of healthy and affected animals. 1462 dairy cows between 5.-65. days in milk were examined on 68 Bavarian farms. Milk and blood samples were taken once a week for a 7-week period per farm and body-condition-scoring, backfat thickness measurement and Metricheck examination, to evaluate uterine health, were performed. Milk samples were analysed for milk fat, milk protein, lactose, urea, ß-hydroxybutyrate and non-esterified fatty acids (indirect measurement, based on IR spectra), cell count, and milk haptoglobin. Blood samples were analysed for creatinine, aspartate aminotransferase, gamma-glutamyl transferase, glutamate dehydrogenase, total protein, albumin, creatine kinase, ß-hydroxybutyrate, non-esterified fatty acids, and blood haptoglobin.Cluster analyses were performed to determine cut-off values for haptoglobin. Besides milk haptoglobin (µg/ml) and blood haptoglobin (µg/ml), cell count (cells/ml milk), milk fat (%), milk protein (%), non-esterified fatty acids in blood (mmol/l), lactation number, days in milk, breed, season, and milk yield (kg) were included as significant input variables (p<0.005) in the cluster analyses. Cluster analysis, using k-means resp. k-prototypes algorithms, resulted in 5 (clusters 1-5 M1) resp. 4 different clusters (clusters 0-3 M2 and 0-3 B).A cut-off value of 0.5 µg/ml haptoglobin in milk was determined for the differentiation of healthy and affected animals. As milk is an easily available substrate, routine determination of haptoglobin in milk might be a suitable parameter for animal health monitoring. Using the detected cut-off value, apparently healthy animals with subclinical inflammatory diseases can be identified more quickly.

Comparison of electronic nose and conventional cow-side diagnostic tools for detection of ketosis in early lactation dairy cows

Rapid diagnosis of ketosis in dairy cows is imperative for treatment and managing economic losses. Cow-side ketosis diagnostic tools are greatly needed. The objective of this study was to compare three tools for the detection of ketosis, using serum β-hydroxybutyrate (BHB) as the gold standard. The di­agnostic tools tested were: (1) Precision Xtra® handheld blood ketone meter, (2) ReliOn® urine ketone test strip, and (3) Cyra­nose 320® electronic nose (eNose) for use on milk and urine. Dairy cows (n = 60) were sampled immediately post-calving. Whole blood, serum, milk, and urine were collected and ana­lyzed on the same day. Each modality was compared to BHB to determine sensitivity and specificity. Positive predictive value (PPV) and negative predictive value (NPV) were calculated across a range of ketosis, consistent with reported prevalence (10-35%) in U.S. dairy operations. Urine ketone strips provided the highest specificity (99.2%), yet low sensitivity (58.6%). The Precision Xtra demonstrated adequate sensitivity (93.8%) and specificity (92.9%). The eNose had substandard sensitivity and specificity when used on milk (Sn: 58.8%; Sp: 44.3%) and urine (Sn: 18.8%%; Sp: 80.6%) compared to the other modalities. Al­though the actual predictive values change with prevalence, urine ketone test strips had the highest PPV (89.5-97.6%) and Precision Xtra had the highest NPV (99.3-96.5%) across all simulated ketosis prevalences. Both urine ketone test strips and the Precision Xtra are adequate cow-side ketosis detection tools. Further optimization of the eNose is needed before de­ployment as a field diagnostic tool.

PSIV-16 Factors Affecting the Lh Release and Ovulatory Response to a Gnrh Treatment in Lactating Dairy Cows on Day 7 of the Estrous Cycle

Abstract This study evaluated factors affecting LH release and ovulation in response to a treatment with a conventional dose of gonadorelin (GnRH), in lactating dairy cows on day 7 of the estrous cycle. Factors evaluated were: GnRH preparation (ready-to-use vs. lyophilized), body condition score (BCS), parity, days in milk (DIM), milk yield and dominant follicle (DF) diameter, at the time of GnRH treatment. Seven days after an artificial insemination, preceded by a synchronization protocol, lactating Holstein cows were evaluated by ultrasound and those with a corpus luteum (CL) and a DF ≥10 mm were randomly assigned to receive 100 µg GnRH ready-to-use solution (Fertagyl; MSD, Brazil) or lyophilized (Profertil; J.A. Animal Health, Brazil) diluted just before its administration. Overall, 106 cows (BCS = 3.1 ± 0.1; DIM = 96.7 ± 4.2; 39.7 ± 0.7 kg of milk/d) were assigned to GnRH treatments. Ovulation was determined by ultrasound examinations 2 d after GnRH treatment, by disappearance of the DF, and confirmed 5 d later by the presence of an accessory CL. In a subset of cows (n = 33), blood samples were collected just before the GnRH treatment, and 2 and 4 h later, to evaluate circulating P4 and LH concentrations. Data were analyzed by GLIMMIX (SAS 9.4). Treatment effect and its interaction were included in the analyses of all other factors. Differences were declared when P ≤ 0.05 and tendency when 0.053.0 (1.4 ± 0.2 vs 0.7 ± 0.1 ng/mL; Table 1). Moreover, cows with DF ≤12 mm had greater LH peak than cows with DF &amp;gt;12 mm (1.3 ± 0.2 vs. 0.9 ± 0.1 ng/mL; Table 2). However, these factors did not affect ovulation. Neither milk yield nor DIM affected LH peak or ovulation. In conclusion, although no differences were detected on LH peak, primiparous cows on day 7 of the estrous cycle had greater ovulation when treated with Profertil compared with Fertagyl. Moreover, regardless of treatment, greater BCS and larger DF (&amp;gt;12 mm) at the time of GnRH treatment were associated with decreased LH peak, however, without impairing ovulation.

PSVI-30 Effects of Different Cobalt Sources on Ruminal Fermentation of Lactating Dairy Cow Diets in a Dual-Flow Continuous Culture System

Abstract The objective of this study was to evaluate the effects of different sources of cobalt in a lactating dairy cow diet on in vitro ruminal fermentation. All diets provided the same amount of supplemental Co (1 mg per kg of diet DM) included in a premix with a targeted inclusion level of 2.5% of diet DM. Treatments were cobalt carbonate (CON), and three alternative Co sources; alternative source 1 (AS1), alternative source 2 (AS2), and alternative source 3 (AS3). Eight dual-flow continuous culture fermenters were used in a replicated 4 × 4 Latin square. Experimental periods were 10 d (7 d adaptation and 3 d sample collection). Composite samples of daily effluents were collected and analyzed for NH3-N, lactate, and VFA concentration as well as for nutrient digestibility. Samples of ruminal content were collected from each fermenter at 0, 1, 2, 4, 6, and 8 h after feeding to determine lactate, NH3-N, and pH kinetics. All data were analyzed using PROC MIXED of SAS and the repeated variable of time was included for pH, lactate, and NH3-N. There were neither treatment effects nor interactions between treatment and time for pH, NH3-N, and lactate concentrations, indicating a similar Co kinetics across treatments. With regards to lactate pool, we did not observe treatment effects for L-lactate; however, we observed treatment effects for D-lactate and total-lactate as seen in Table 1. Analyses of total and individual VFA, N utilization, and nutrient degradation are still undergoing, hence, it is possible that Co sources have effects on ruminal fermentation.

PSXIV-17 Examining Mammary Gland Transcriptomic Profiles Using Rna-Seq in Slick and Wild-Type Haired Holstein Cattle Under Tropical Conditions

Abstract In lactating dairy cows, heat stress reduces feed intake, alters the metabolism of the animal, and compromises milk production. Holstein cattle carrying the prolactin receptor gene mutation (SLICK) have been shown to have superior performance under tropical conditions by exhibiting increased milk yield compared with wild-type haired Holstein cattle (WT). Recent research indicated that SLICK cattle have greater mammary gland blood flow and lower vaginal temperatures, while maintaining prolonged voluntary exposure to direct solar radiation than their WT counterparts. Nevertheless, differences in molecular mechanisms between genotypes at the mammary gland level have been unexplored. The objective of the current study was to investigate possible differences in the mammary gland transcriptome from SLICK (n = 7) and WT (n = 6) Puerto Rican Holstein cattle. At 160 ± 3 days in milk (DIM), ultrasound guided mammary biopsies were collected from the left rear quarter of each animal and samples were snap frozen. Unstranded RNA-seq libraries were created from the frozen mammary tissue and sequenced using Illumina Novaseq 2x150bp. Quantification of expression was done by salmon [v1.9.0] using the Bos taurus (ARS UCD1.3) transcriptome database. Testing for significant differential expression (DE) was done using a pipeline consisting of the R packages tximport [v1.26.1] and edgeR [v3.40.2]. The fry method from edgeR was used to do gene set enrichment analysis (GSEA) for Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and Gene Ontology (GO) terms. A single gene (GeneID:513329, major allergen Equ c 1 isoform X2) showed significant (B.H. adjusted P-value ≤ 0.05) differential expression. Aligning the protein sequence for this gene using the BLASTp against the non-redundant (NR) database revealed high similarity to two pheromones, salivary lipocalin 2 and salivary lipocalin-like. Both the KEGG pathway and GO term GSEA showed no statistically significant enrichment at B.H. adjusted P-value ≤ 0.05; however, using a less stringent criteria with a normal P-value ≤ 0.05, multiple relevant pathways were identified. For example, the KEGG pathway analysis revealed that the arachidonic acid metabolism pathway (bta00590) was enriched, and the tight junction function pathway (bta4530) was depleted in the SLICK Holstein samples. Among the GO analysis, genes were found to be downregulated in response to cold (GO:0009409), hair follicle development (GO:0001942), and vasoconstriction (GO:0042310), whereas positive regulation of oxytocin production (GO:0140668), and defense response to Gram-positive bacterium (GO:0050830) were upregulated. In conclusion, differences in gene expression were limited, but after enrichment interesting pathways were revealed and deserve further exploration to aid in elucidating different molecular mechanisms between SLICK and WT cattle.