Holstein Cows Research Articles

Post-milking application of a Lacticaseibacillus paracasei strain impacts bovine teat microbiota while preserving the mammary gland physiology and immunity.

Bovine mastitis (BM) is a major disease in dairy industry. The current approaches- mainly antibiotic treatments- are not entirely effective and may contribute to antimicrobial resistance dissemination, rising the need for alternative treatment. The present study aims to evaluate the impact of post-milking application of Lacticaseibacillus paracasei CIRM BIA 1542 (Lp1542) on the teat skin (TS) of 20 Holstein cows in mid lactation, in order to reinforce the barrier effect of the microbiota naturally present on the teat. Treatment (Lp1542, iodine or no treatment) was applied post-milking twice a day on the 4 teats of healthy animals for 15 days. Blood and milk samples, and TS swabs were collected at day (D)1, D8, D15 and D26 before morning milking and at D15 before evening milking (D15E) to evaluate Lp1542 impact at the microbial, immune and physiological levels. Lp1542 treatment resulted in a higher lactic acid bacteria and total microbial populations on TS and in foremilk (FM) at D15(E) compared with iodine treatment. Metabarcoding analysis revealed changes in the composition of TS and FM microbiota, beyond a higher Lacticaseibacillus abundance. This included a higher abundance of Actinobacteriota, including Bifidobacterium, and a lower abundance of Pseudomonadota on TS of Lp1542 compared with iodine-treated quarters. In addition, Lp1542 treatment did not trigger any major inflammatory response in the mammary gland, except interleukin 8 production and expression which tended to be slightly higher in Lp1542-treated cows compared with the others. Finally, Lp1542 treatment had no impact on the mammary epithelium functionality (milk yield and composition) and integrity (epithelial cell exfoliation into milk and milk Na+/K+ ratio). Altogether, these results indicate that a topical treatment with Lp1542 is safe with regard to mammary gland physiology and immune system, while impacting its microbiota, inviting us to further explore its effectiveness for mastitis prevention.

Composition and fatty acid profile of milk from cows fed diets supplemented with raw and n-3 PUFA-enriched fish oil

Dietary supplementation of ruminants with fish oil is a strategy for favorably modifying the fatty acid composition of milk fat. This study investigated the effect of supplementing cows’ diet with fish oil after low-temperature crystallisation (LTC-FO) compared to its raw form (FO) on milk yield, milk components (fat, protein, and lactose), and milk fatty acid profile. Twenty-four mid-lactating multiparous Polish Holstein–Friesian cows fed a total-mix ration were randomly assigned to two homogeneous groups (n = 12 cows each) and supplemented with LTC-FO or FO at 1% of dry matter. Milk samples were collected on days 14 and 30 of the 30-day experiment. No significant differences between the groups in terms of milk yield, milk protein, and lactose content were found, however, the fat yield and content decreased in the LTC-FO group. Milk fat from cows in the LTC-FO group contained significantly higher levels of C18:1 trans-11, C18:2 cis-9, trans-11, C18:3n − 3, C20:5, and C22:6, and lower levels of saturated fatty acids compared to the FO group (p < 0.05). Therefore, LTC-FO may be a more efficient feed additive than FO and may serve as a practical way to modify the fatty acid composition of milk fat.

Novel Approach for Evaluating Pregnancy-Associated Glycoprotein and Inflammation Markers during the Postpartum Period in Holstein Friesian Cows

Novel Approach for Evaluating Pregnancy-Associated Glycoprotein and Inflammation Markers during the Postpartum Period in Holstein Friesian Cows

Determining the Association of the Dry Period Duration with Dystocia and Stillbirths in Dairy Cows by Considering Parity, Season, and Gestation Length

This study aimed to assess the relationship between the length of the dry period (DL) and the risks of dystocia and stillbirths in Holstein cows. A total of 1072 healthy cows in lactations 1 and ≥2 were categorized based on the DL (mean: 58.07 ± 0.33 days) into three groups: short DL (&lt;40 days; 13.0% of cows), medium DL (40–70 days; 60.1%), and long DL (&gt;70 days; 26.9%). Dystocia occurred in 12.4% of cows, while stillbirths accounted for 4.1% of calves. The medium DL group had the highest number of unassisted calvings. The dystocia rates were 11.4% for cows with gestation (GA) ≤ 274 days; 6.0% for cows with GA = 275–282 days; and 19.9% for cows with GA ≥ 283 days (p &lt; 0.001). In season 1 (November–April), dystocia occurred in 15.0% of cases compared to 8.8% in season 2 (May–October) (p &lt; 0.001). The stillbirth rates ranged from 3.6% to 4.0% for cows with medium and long DLs; while those with a short DL had 5.8% (p &lt; 0.05). The stillbirth rates were 5.2% for cows with GA ≤ 274 days; 3.2% for cows with GA = 275–282 days; and 5.1% for cows with GA ≥ 283 days (p &lt; 0.001). Season 1 had a stillbirth rate of 4.8%, while season 2 had a stillbirth rate of 3.3% (p &lt; 0.001). This research provides insights that could assist the dairy industry in making informed decisions to reduce the incidence rates of dystocia and stillbirths in cows.

A new strain of Saccharomyces cerevisiae in diets of lactating Holstein cows improved feed efficiency and lactation performance

Abstract This study compared the effects of feeding a new strain of Saccharomyces cerevisiae HSA2020 with a commercial strain on in vitro rumen fermentation and production performance of dairy cows. Permeate was used as a substrate for the laboratory production of the new strain of S. cerevisiae after the hydrolysis by β–galactosidase (5000 µ/mL at 37°C). Two experiments were conducted: in Experiment 1, the effects of three levels (1, 2 and 3 g/kg dry matter) of S. cerevisiae on in vitro ruminal fermentation kinetics were evaluated. In Experiment 2, for 60 days, sixty multiparous Holstein cows (639±24.8 kg BW, 3±1 parity, 7±1 days in milk, with a previous milk production of 23±2.0 kg/d) during the previous lactation, were randomly assigned to 3 treatments in a completely randomized design. Cows were fed without any additives (control treatment) or supplemented with 2 g/kg feed daily of laboratory produced (PY)or commercial (CY) S. cerevisiae. In Experiment 1, inclusion of PY and CY increased (P&lt;0.05) gas production, propionate, and nutrient disappearance, while decreased (P&lt;0.05) methane production and protozoal count. Moreover, in Experiment 2, PY followed by CY increased (P&lt;0.01) nutrient digestibility, and serum concentrations of total protein, albumin, and glucose (P&lt;0.05). Higher daily milk yield, and milk energy output were observed with PY and CY without affecting concentrations of milk components or milk fatty acid profile. Compared to control, increased feed efficiency was observed with PY and CY. Compared to PY, CY increased serum concentrations of urea-N and decreased triglycerides, while PY decreased serum aspartate transaminase and increased concentration of conjugated linoleic acids in milk. In early lactating cow diets, both strains of S. cerevisiae improved production performance at 2 g/kg improved production performance, and minimal differences between strains were found.

Predicting dyscalcemia at 4 days in milk using activity and rumination data in multiparous Holstein cows

Dyscalcemia, reduced blood calcium at 4 DIM, is associated with reduced milk production and reproduction and increased risk for negative health events. Cowside testing of blood calci­um to diagnose dyscalcemia is difficult and alternative methods to identify dyscalcemia are needed. Our objectives were to use activity and rumination data to predict dyscalcemia.

Behavioral consistency of competitive behaviors and feeding patterns in lactating dairy cows across stocking densities at the feed bunk

IntroductionHigh feed bunk stocking densities can differentially impact individual dairy cows’ competitive behaviors, feeding patterns, and feed efficiency. Our objective was to manipulate feed bunk stocking densities to evaluate intra-individual behavioral consistency across stocking densities and quantify associations with feed efficiency and production.MethodsThirty-two primiparous (130.7 ± 29.0 days in milk, DIM) and 32 multiparous (111.3 ± 38.3 DIM) lactating Holstein cows were housed with 32 roughage intake control (RIC) bins. Each cow was assigned to share 8 bins with others of the same parity and similar body weight (16 cows/block; 2:1 feed bunk stocking density except during tests). Competition and feeding patterns were evaluated via video and RIC data, respectively, at 3 stocking densities (1:1, 2:1, 4:1 cows/bin) during 1-h tests (2 tests/stocking density; 6 tests/cow) following 2 h feed deprivation. Residual feed intake (RFI) was calculated across the 45-d study as the difference between observed and predicted dry matter intake (DMI) after accounting for known energy sinks. Linear mixed models were used to evaluate the overall impact of test stocking density on competition and feeding patterns. To evaluate intra-individual consistency between stocking densities, individual stability statistic (ISS) scores were computed. Correlational relationships were determined between RFI and ISS scores.Results and dicsussionCows displayed the most competitive behaviors at 2:1 stocking density (p &amp;lt; 0.0001) but experienced the highest rate of contacts per minute of eating time at 4:1 (1:1 vs. 2:1 vs. 4:1: 0.09 vs. 0.95 vs. 1.60 contacts/min; p &amp;lt; 0.0001). Feeding patterns were modulated as stocking density increased; eating rate increased (0.16 vs. 0.18 vs. 0.22 kg/min; p &amp;lt; 0.001) as eating time (40.3 vs. 28.2 vs. 14.6 min; p &amp;lt; 0.001) and DMI decreased (6.3 vs. 5.1 vs. 3.0 kg; p &amp;lt; 0.001). As stocking density doubled, individuals remained consistent (p = 0.018) in time spent near others actively eating and tended to remain consistent in competition behavior and feeding patterns (0.053 ≤ p ≤ 0.094). Between 2:1 and 4:1, cows with higher DMI and milk production were more consistent in first-visit DMI and duration. Feed efficiency was not associated with behavioral consistency across the tests (p ≥ 0.14). Nonetheless, feed bunk stocking density has behavioral implications which should be considered in nutritional management decisions.

Identification and Characterization of long non-coding RNAs in Mammary Gland Tissues of Chinese Holstein Cows.

LncRNAs (Long non-coding RNA) is an RNA molecule with a length more than 200bp. LncRNAs can directly act on mRNA, thus affecting the expression of downstream target genes and proteins, and widely participate in many important physiological and pathological regulation processes of the body. In this study, RNA-Seq was performed to detect lncRNAs from mammary gland tissues of 3 Chinese Holstein cows, including 3 cows at 7 days before calving and the same 3 cows at 30 days postpartum (early lactation stage). A total of 1,905 novel lncRNAs were detected, 57.3% of the predicted lncRNAs are ≥ 500bp and 612 lncRNAs are intronic lncRNAs. The exon number of lncRNAs ranged from 2 to 10. A total of 96 lncRNAs were significantly differentially expressed between two stages, which 47 were upregulated and 49 were downregulated. Pathway analysis found that target genes were mainly concentrated on the ECM-receptor interaction, Jak-STAT signaling pathway, PI3K-Akt signaling pathway and TGF-beta signaling pathway. This study revealed the expression profile and characteristics of lncRNAs in the mammary gland tissues of Holstein cows at non-lactation and early lactation period, and providing a basis for studying the functions of lncRNAs in Holstein cows during different lactation periods.

Ration particle size has different effects on digestive but not production parameters in higher-yielding (Holstein) compared to lower-yielding (Girolando) cows.

The aim of the study was to evaluate the effect of total mixed ration particle size (length) and breed of cow on intake dynamics, animal performance and CH4 emissions, comparing high yielding Holstein and low yielding Girolando cows. The experimental design was 2 × 2 Latin Square arranged as a crossover factorial scheme with two diets (short particle size, SPS and long particle size, LPS) and the two breed compositions. The design comprised two periods of 26 d each, where all data collection was performed at cow level. No influence of the particle size occurred for the passage rate, neutral detergent fiber digestibility, performance and milk composition, methane emissions or ruminal fermentation parameters. Girolando cows had greater dry matter intake (DMI) when fed SPS, while Holsteins had the same (P < 0.05). Girolando cows had lower dry matter digestibility when fed LPS compared to SPS, while Holsteins had the opposite effect (P < 0.05). Also, the digestibility of crude protein and non-fibrous carbohydrates decreased in Girolando cows fed LPS, but not in Holsteins (P < 0.05). Girolando cows reduced DMI by 10.6% when fed LPS diet (P < 0.05). Girolando had an increased eating rate (+24 g of DM/min; P < 0.05) compared to Holstein cows, but Holstein cows had a lower CH4 intensity (by 29.7%: P < 0.05). Girolando cows increased the dry matter intake when fed a diet with short particle size, while the same did not happen in Holsteins. Dry matter digestibility increased in Holsteins when fed long particle size, while the opposite was observed in Girolando cows. Nutrient digestibility was reduced in Girolando cows when fed short particle size. Particle size did not influence eating time, eating rate, feed trough visits, visits with intake, milk yield and composition regardless of the breed. Reducing particle size increased CH4 intensity in both breeds.

Impact of parity number, milk production and somatic cell count on the reproduction of Holstein cows - ERRATUM.

Impact of parity number, milk production and somatic cell count on the reproduction of Holstein cows - ERRATUM.

Identification and characterization of whole blood gene expression and splicing quantitative trait loci during early to mid-lactation of dairy cattle

BackgroundCharacterization of regulatory variants (e.g., gene expression quantitative trait loci, eQTL; gene splicing QTL, sQTL) is crucial for biologically interpreting molecular mechanisms underlying loci associated with complex traits. However, regulatory variants in dairy cattle, particularly in specific biological contexts (e.g., distinct lactation stages), remain largely unknown. In this study, we explored regulatory variants in whole blood samples collected during early to mid-lactation (22–150 days after calving) of 101 Holstein cows and analyzed them to decipher the regulatory mechanisms underlying complex traits in dairy cattle.ResultsWe identified 14,303 genes and 227,705 intron clusters expressed in the white blood cells of 101 cattle. The average heritability of gene expression and intron excision ratio explained by cis-SNPs is 0.28 ± 0.13 and 0.25 ± 0.13, respectively. We identified 23,485 SNP-gene expression pairs and 18,166 SNP-intron cluster pairs in dairy cattle during early to mid-lactation. Compared with the 2,380,457 cis-eQTLs reported to be present in blood in the Cattle Genotype-Tissue Expression atlas (CattleGTEx), only 6,114 cis-eQTLs (P < 0.05) were detected in the present study. By conducting colocalization analysis between cis-e/sQTL and the results of genome-wide association studies (GWAS) from four traits, we identified a cis-e/sQTL (rs109421300) of the DGAT1 gene that might be a key marker in early to mid-lactation for milk yield, fat yield, protein yield, and somatic cell score (PP4 > 0.6). Finally, transcriptome-wide association studies (TWAS) revealed certain genes (e.g., FAM83H and TBC1D17) whose expression in white blood cells was significantly (P < 0.05) associated with complex traits.ConclusionsThis study investigated the genetic regulation of gene expression and alternative splicing in dairy cows during early to mid-lactation and provided new insights into the regulatory mechanisms underlying complex traits of economic importance.

Determination of aneuploidy/polyploidy in Holstein cows with a history of abortion

Determination of aneuploidy/polyploidy in Holstein cows with a history of abortion

PSV-1 A comparison of Holstein-cross cattle and beef-cross cattle in terms of performance and carcass quality

Abstract Crossbreeding Holstein cows to beef sires has increased in popularity as a means to increase marketability of the dairy offspring. A large portion of these dairy-cross animals are offspring of Holstein cows and Angus bulls. The objective of this study was to evaluate the carcass quality of 3 crossbred beef steers (Hereford x Angus) and 3 dairy x beef cross steers (Holstein x Angus). These animals had been a part of a previous study evaluating the additive effect of implanting strategy combined with inclusion of a beta-agonist and represent the three different treatments evaluated on that study with one dairy-cross and one beef-cross animal coming from each treatment. All steers were fed a mixed ration consisting of 30.0% rye silage, 28.0% DDGS, 30.0% rolled corn, 10.5% soybean meal, and 1.5% mineral supplement (22.0% CP, 2.90 Mcal ME/kg DM). Animals were fed daily at 0700 and 1700 and weighed weekly at 0630. For the duration of the trial, animals were housed in drylot pens with ad libitum access to feed and water and had shade structures in each pen. Following a 15-d adaptation period, feed intake was recorded for 45 d. Data were analyzed as a completely random design in SAS v9.4. The animals were evaluated in terms of growth and performance, carcass quality, and feed efficiency. There was no difference in intake for either treatment; however, beef-cross steers gained significantly more than their dairy-cross counterpart on the same diet. After the intake portion of the study was completed, all six chosen animals were slaughtered and evaluated for carcass quality. Following 14 d aging, samples from the ribeye area were collected from each animal and subjected to sensory analysis and other assessments of quality. Other than a numerical difference in marbling score between treatments, there were no statistical differences in meat quality between the two crosses indicating that dairy-cross animals are an important addition to the beef industry.

PSV-11 In vitro screening of selected compounds to reduce ruminal methane production

Abstract Methane is a natural product of rumen fermentation and emissions from ruminant livestock represent a major environmental concern. Methane is not only a potent greenhouse gas but also represents a loss of energy efficiency for the host. The objective of this study was to perform in vitro screening of a range of compounds with potential anti-methanogenic activity, including polyphenols, flavonoids, fatty acids, amino acids, and salts. We aimed to select compounds conferring up to a 20% reduction in CH4 for further investigations. The substances tested included carvacrol, coumaric acid, coumarin, flavanone, gallic acid, glycerol monolaurate (GML), glycine, methylene blue, naringin, quercetin, quinic acid, resorcinol, rutin, tannic acid, vanillic acid, and zinc acetate. These substances varied in their mechanisms of action and were selected based on known antimicrobial or anti-methanogenic properties. The experiment was designed as a randomized block experiment, with treatments tested in triplicates across four batches (n = 228 samples) using the same treatments and experimental conditions. Fresh rumen contents were manually collected from two rumen-fistulated lactating Holstein cows, 3 h after their morning feeding. Rumen contents were blended at a 2:1 ratio, filtered through a four-layered cheesecloth, and added to McDougall’s solution at a 2:1 ratio. Final media (9 mL) was added to a 20 mL Bellco flask containing 150 mg of total mixed ration (TMR) ground to 1 mm. Each batch also had three flasks without TMR and no treatment (blank flasks), three flasks containing only TMR without treatment (negative control), and three flasks containing TMR and treated with chloroform (positive control), resulting in a total of 19 treatments. The end-products of in vitro batch fermentations were assessed after 24 h of incubation, and samples from each flask were collected for gas composition analysis using gas chromatography. Volatile fatty acids were determined using high-performance liquid chromatography (HPLC). The data were analyzed using R Studio, and the following model was applied: yij = µ + treatmenti + batchj + ℇij. Methane production (measured in parts per million, ppm) increased when GML, naringin, and quercetin were added compared with the negative control. In contrast, the addition of carvacrol, glycine, tannic acid, and methylene blue resulted in a decrease of up to 25% in methane production. These compounds show potential to alter ruminal fermentation and mitigate methane production and will be selected for evaluation of synergistic interactions and effects on the rumen microbial communities.

PSV-10 Evaluation of the effect of probiotic feed additives in the diet to improve dairy production and quality measures

Abstract There is limited information regarding the effectiveness of probiotic feed additives in the diet of lactating dairy cows. This study aimed to determine the effect that Fastrack probiotic had on the yield and milk quality measures of lactating dairy cows. To accomplish this goal, lactating Holstein cows (n = 80) were equally divided into two treatment groups: one supplemented with a probiotic (PRO) and one that did not receive the probiotic supplement (CON). The cows remained in their treatment groups for the duration of the 120-d study and were given ad libitum access to a total mixed ration consisting of 35% corn silage, 30% rolled corn, 10.5% soybean meal, 23% DDGS, and 1.5% mineral supplement. Cows on the PRO treatment were given 1 kg of DDGS once a day at milking that had the probiotic mixed in while the CON treatment were given 1 kg of the same DDGS that did not have the probiotic included. Preliminary results of this study show a decrease in individual treatment records for cows on the PRO treatment and an increase of 2 kg of milk yield per day.

PSV-12 Microbial community structure of dairy cattle is stable through oscillating crude protein inclusion

Abstract Diet has an important role in shaping the structure of rumen microbial communities. However, little is known about the interaction between dietary crude protein (CP) level and CP feeding pattern on the rumen microbiome of dairy cows. Here, the objective was to evaluate the influence of CP level (low protein [LP], 13.8%; high protein [HP], 15.5% of dry matter [DM] basis) and CP feeding pattern (OF = oscillating, SF = static) on the composition and diversity of the rumen microbiome of lactating dairy cows using 16S rRNA gene amplicon sequencing. Rumen-cannulated Holstein cows (n = 8) in mid- to late-lactation were assigned to a 2 x 2 factorial experiment consisting of 4 experimental periods of 28 d. Each experimental period had an adaptation phase to the diet (24 d) and a sampling phase (d 25 to 28). The treatments with oscillating feeding alternated diets every 48 h to vary CP above and below the mean CP level (OF-LP = 13.8 ± 1.8%; OF-HP = 15.5 ± 1.8% CP of DM) whereas diets were constant in the static feeding (SF-LP = 13.8%; SF-HP = 15.5% CP of DM). According to the NASEM (2021) model predictions the LP diet supplied 94% of the microbial protein requirement while the HP diet exceeded (104%) requirement. Rumen samples were collected 4 h after feeding through a rumen cannula and amplicon libraries were generated targeting the V4 region of the 16S rRNA gene. The amplicon sequences were analyzed in qiime2. Sequences where trimmed based on their quality and then grouped in ASVs using DADA2. The ASVs were used to analyze the composition and diversity of the rumen microbiome in each treatment. Alpha diversity of the rumen microbiome did not change across treatments (Kruskal Wallis, P &amp;gt; 0.05), but Pielou’s evenness increased by 0.01 units (Kruskal Wallis, P = 0.04). These results support the hypothesis that the rumen microbiome is stable to oscillating CP feeding patterns and compensates for the changes in crude protein content in the diet. Further research is required to understand the dynamics of this compensation and what other metabolic processes in the ruminant contribute to maintaining production under an oscillating diet.

294 Development of a model to predict forage intake and growth of bottle-fed Holstein calves

Abstract Models to predict intake and growth of preweaning calves have received less attention than postweaning calves. The objective was to develop a model to predict forage intake and growth of bottle-fed Holstein calves. Data on milk intake, alfalfa hay intake, and body weight (BW) of 40 Holstein calves from birth to 200 d of age were acquired from Abdelsamei (1989). Milk and forage intake equations were those used by Lancaster et. al. (2021; 10.1093/jas/skaa406). NASEM growth equation evaluation and new equation development were performed using a dataset compiled from the literature by Hildebrand et al. (2022; 10.1093/jas/skac064.321). The mean absolute error to predict milk intake was less for WOOD at peak milk less than 10.88 kg/d, and was less for NASEM at peak milk greater than 10.88 kg/d. A combination of NASEM and WOOD milk yield equations to predict milk intake resulted in CCC of 0.969 and MB of -0.74% and was used to predict milk intake in subsequent analyses. Prediction of forage intake by TED06, BAK76, TED09A, TED09B, and HOL82 had CCC of 0.878, 0.920, 0.729, 0.874, and 0.234 with MB of -17.49, -1.58, -64.40, -35.60, and -341.16%, respectively. Prediction of BW for the same intake equations with the NASEM growth equation had CCC of 0.876, 0.929, 0.819, 0.864, and 0.402 with MB of -21.54, -14.67, -30.10, -25.13, and -99.78%, respectively. With observed BW, prediction of forage intake by TED06, BAK76, TED09A, TED09B, and HOL82 resulted in CCC of 0.935, 0.936, 0.958, 0.964, and 0.640 with MB of -0.55, 6.57, -11.90, -8.83, and -92.26%, respectively, indicating high precision and moderate accuracy. With observed forage intake, prediction of BW by the NASEM growth equation resulted in CCC of 0.926 and MB of -17.08% indicating high precision and poor accuracy. Evaluation of the NASEM growth equation in Holstein cattle resulted in CCC of 0.329 and MB of 61.47%. A new growth equation was developed: EBG, kg/d = 0.78498 ± 0.24035*RE, Mcal/d^(0.78500 ± 0.06033)*EBW, kg^(-0.14323 ± 0.0742) with RMSE = 0.0599 ± 0.0207 and R2 = 0.8795 ± 0.1078. With observed forage intake, prediction of BW with the new growth equation resulted in CCC of 0.992 and MB of -0.11%. With the new growth equation, prediction of forage intake by TED06, BAK76, TED09A, TED09B, and HOL82 resulted in CCC of 0.914, 0.766, 0.881, 0.901, and 0.412 with MB of 15.47, 40.53, 18.11, 17.02, and -172.88%, respectively. Prediction of BW resulted in CCC of 0.978, 0.940, 0.968, 0.969, and 0.701 with MB of 2.83, 8.91, 3.87, 3.92, and -38.73%. In conclusion, prediction of forage intake and BW in Holstein calves were hindered by use of the NASEM growth equation, and a new growth equation more precisely and accurately predicted forage intake and body weight.

Effect of commercial fibrolytic enzymes application to normal- and slightly lower energy diets on lactational performance, digestibility and plasma nutrients in high-producing dairy cows

The inclusion of fibrolytic enzymes in the diet is believed to have positive effects on animal production. Hence, the objective of this study was to investigate the impact of supplementing diets with a commercial fibrolytic enzyme preparation (Vistamax; mixture of xylanase and cellulase) derived from Trichoderma reesei on lactational performance, digestibility, and plasma nutrient levels in high-producing dairy cows. Two dietary energy levels were considered: a normal energy diet (metabolizable energy = 2.68 Mcal/kg) and a slightly lower energy diet (metabolizable energy = 2.55 Mcal/kg). A total of 120 lactating Holstein cows (parity = 2; Days in Milk = 113 ± 23) were randomly assigned to four treatment groups using a 2 * 2 factorial arrangement. The dietary treatments consisted of: (1) normal energy diet without enzyme supplementation (NL); (2) normal energy diet with enzyme supplementation (NLE); (3) slightly lower energy diet without enzyme supplementation (SL); and (4) slightly lower energy diet with enzyme supplementation (SLE). The amount of enzyme added to the diets was determined based on previous in vitro studies and supplier recommendations. The enzyme and premix were mixed prior to the preparation of the total mixed ration, and the trial lasted for a duration of 42 days. The results indicated that the application of the fibrolytic enzyme did not have a significant effect on dry matter intake (DMI), but it did enhance the digestibility of dry matter (DM), neutral detergent fiber (NDF), potentially digestible NDF (pdNDF), organic matter (OM), milk production, milk urea nitrogen (MUN), and blood urea nitrogen (BUN). On the other hand, the slightly lower energy diet resulted in a decrease in DMI, milk production, milk protein yield, plasma free amino acids (FAA), and an increase in plasma B-hydroxybutyrate (BHBA). In conclusion, the inclusion of the fibrolytic enzyme in the diets of dairy cows led to improvements in the digestibility of DM, NDF, pdNDF, OM, milk production, and feed efficiency. Furthermore, the application of the enzyme to the slightly lower energy diet resulted in milk production levels comparable to those observed in cows fed the untreated normal energy diet.

Identification of Molecular Profile of Ear Fibroblasts Derived from Spindle-Transferred Holstein Cattle with Ooplasts from Taiwan Yellow Cattle under Heat Stress.

Global warming has a significant impact on the dairy farming industry, as heat stress causes reproductive endocrine imbalances and leads to substantial economic losses, particularly in tropical-subtropical regions. The Holstein breed, which is widely used for dairy production, is highly susceptible to heat stress, resulting in a dramatic reduction in milk production during hot seasons. However, previous studies have shown that cells of cows produced from reconstructed embryos containing cytoplasm (o) from Taiwan yellow cattle (Y) have improved thermotolerance despite their nuclei (n) being derived from heat-sensitive Holstein cattle (H). Using spindle transfer (ST) technology, we successfully produced ST-Yo-Hn cattle and proved that the thermotolerance of their ear fibroblasts is similar to that of Y and significantly better than that of H (p < 0.05). Despite these findings, the genes and molecules responsible for the different sensitivities of cells derived from ST-Yo-Hn and H cattle have not been extensively investigated. In the present study, ear fibroblasts from ST-Yo-Hn and H cattle were isolated, and differentially expressed protein and gene profiles were compared with or without heat stress (hs) (42 °C for 12 h). The results revealed that the relative protein expression levels of pro-apoptotic factors, including Caspase-3, -8, and -9, in the ear fibroblasts from the ST-Yo-Hn-hs group were significantly lower (p < 0.05) than those from the H-hs group. Conversely, the relative expression levels of anti-apoptotic factors, including GNA14 protein and the CRELD2 and PRKCQ genes, were significantly higher (p < 0.05) in the ear fibroblasts from the ST-Yo-Hn-hs group compared to those from the H-hs group. Analysis of oxidative phosphorylation-related factors revealed that the relative expression levels of the GPX1 gene and Complex-I, Complex-IV, CAT, and PGLS proteins were significantly higher (p < 0.05) in the ear fibroblasts from the ST-Yo-Hn-hs group compared to those from the H-hs group. Taken together, these findings suggest that ear fibroblasts from ST-Yo-Hn cattle have superior thermotolerance compared to those from H cattle due to their lower expression of pro-apoptotic factors and higher expression of oxidative phosphorylation and antioxidant factors. Moreover, this improved thermotolerance is attributed, at least partially, to the cytoplasm derived from more heat-tolerant Y cattle. Hence, using ST technology to produce more heat-tolerant H cattle containing Y cytoplasm could be a feasible approach to alleviate the negative impacts of heat stress on dairy cattle in tropical-subtropical regions.

Impact of genetic κ-casein variants (A, B, E) on chymosin-induced milk coagulation properties: Application of a new LC–MS-based genotyping method

This study evaluated the impact of κ-casein (κ-CN) protein phenotype (AA (n = 18), AB (n = 18), AE (n = 5), BB (n = 3)) in the raw milk of 44 individual Holstein cows from a single farm on coagulation properties using diffusion wave spectroscopy. κ-CN variants were analyzed using a newly developed LC–MS method in individual milk samples, and relative milk protein fractions were quantified by LabChip-analysis. κ-CN fractions expressed in the percentage of total milk protein, total casein, and β- and κ-CN were then calculated. The gross composition of the individual milk samples and variation between individual cows was analyzed and was rather large, as expected. Traits were analyzed using an ANCOVA model with pH as a covariate.Our results showed that mean percentages of κ-CN fractions increased for κ-CN phenotypes in the order AA < AE < AB < BB. Rennet coagulation time was slightly affected, but curd firmness was significantly affected by κ-CN phenotype (BB > AE > AB > AA) when controlling for pH.