Hasil untuk "Dairying"

Muhammad Ajmal Khan, A. Bach, D. Weary et al.

Sage Taylor, Joy Waite-Cusic

ABSTRACT: Listeria monocytogenes is a foodborne pathogen problematic for the dairy industry, prompting dairy manufacturers to seek antilisterial additives to reduce the risk in dairy products that support the survival and growth. Bacillus spp. have been explored as being potential producers of antilisterial metabolites to inhibit Listeria spp. Bacillus subtilis and Bacillus pumilus were cultured in a food-grade medium mimicking tryptic soy broth supplemented with yeast extract (FG-TSBYE) and processed into foamed cell-free supernatant (CFS-F) to produce a cultured ingredient. This cultured ingredient was evaluated for antilisterial activity in a 96-well broth assay against Listeria target strains (n = 3). Bacillus subtilis Y487 was found to completely inhibit growth of all 3 Listeria target strains, whereas B. pumilus strains (HD49A and VF0409D) produced inhibitory activity against 2 out of 3 strains. Bacillus CFS-F showed good reproducibility with no significant difference found between independent cultures on the same plate. Biological reproducibility was variable for Listeria strains in response to Bacillus CFS-F. Listeria monocytogenes WRLP42 showed some consistency of technical replication (same plate) and good biological replication (across plates), whereas Listeria innocua WRLP438 and L. monocytogenes WRLP96 showed high variability among technical replicates (same plate) and high variability among biological target replication (across plates). Cottage cheese was formulated with freeze-dried CFS-F (CFS-F-FD) and inoculated with Listeria target strains (n = 3) and stored at 7°C for 25 d. The CFS-F-FD from B. pumilus VF0409D and B. subtilis Y487 were effective in delaying the lag phase of L. monocytogenes WRLP96 in cottage cheese by 7 d; however, CFS-F-FD induced changes in the texture and appearance of the cottage cheese. This proof-of-concept study demonstrates the efficacy of Bacillus spp. cell-free supernatant as a potential Listeria control measure in dairy foods. Further research is necessary to optimize antilisterial production and cell-free supernatant processing to minimize product changes.

Y. Roman-Garcia, L. Moraes, D.H. Kleinschmit et al.

ABSTRACT: A meta-analysis was conducted to quantify production responses to chromium (Cr) supplementation and better understand variables that affect this response. Multivariate random and mixed effects models were used to develop and fit all models. The response variable was described by the mean difference of milk yield, ECM, DMI, and milk fat and protein yields between cows that received Cr supplementation and cows in the control group. Treatment means from 28 studies were used to assemble a database of studies designed specifically to investigate the effects of supplementing Cr on dairy cows. Of the 93 treatment means, 38 means fed the Cr starting in the dry period. Overall, Cr supplementation increased production, and the mean difference is affected by stage of lactation (characterized by DIM in our analysis), Cr source (Cr-methionine, Cr-propionate, Cr-chelate, Cr-picolinate, Cr-yeast), and dose (0–19 mg/d). The models for milk yield, milk fat, and milk protein suggest the greatest response for Cr supplementation between a 6 to 7 mg/d supplementation rate. However, the greatest response for DMI was predicted to be at a supplementation rate of 9 mg/d. The models suggest peak mean differences in yields of milk, ECM, fat, and protein at approximately 100 DIM with supplementation of Cr starting at pre- or postcalving. Although the production of ECM maximizes at approximately 100 DIM there is still a benefit in production to feeding Cr up to 168 to 186 DIM, depending on the Cr source.

Mulisa F. Dida, Sergio C. Garcia, Luciano A. Gonzalez

ABSTRACT: Despite extensive research on the environmental effects of dairy farming, comparative GHG emissions from confinement and pasture-based systems remain unclear due to inconsistent findings from prior studies, which were often specific to the local conditions of each system and overlooked carbon sequestration by trees. The present study aimed to compare the GHG emissions of 2 Australian milk production systems (confinement and pasture-based) using a life cycle assessment approach that incorporates C sequestration by trees. The confinement system used a TMR, whereas the grass-based system primarily relied on grazed forage with concentrate supplementation. The Australian Dairy Carbon Calculator, a Tier 3 tool, predicted emission intensity using the National Greenhouse Gas Inventory and Intergovernmental Panel on Climate Change methods, as reported to the United Nations Framework Convention on Climate Change. Emission intensity was calculated as net GHG exchange in CO2 equivalents (CO2eq), allocated to milk and meat. Animal emissions dominated: 85% of total emissions in confinement systems (54% enteric CH4, 31% manure) and 71% in pasture-based systems (58% enteric CH4, 13% manure). The confinement system showed 13% lower enteric CH4 intensity and 88% lower prefarm embedded intensity (kg CO2eq/kg fat- and protein-corrected milk [FPCM]) but 129% higher manure-related GHG intensity than the pasture-based system. Emission intensities for milk (1.02 ± 0.038 vs. 1.07 ± 0.069 kg CO2eq/kg FPCM) and meat (5.51 ± 0.779 vs. 6.76 ± 0.868 kg CO2eq/kg liveweight) were similar between systems. The emission offset by tree C sequestration (kg CO2eq/kg FPCM) was relatively low in both systems, contributing about 1% of total CO2eq emissions in confinement systems and up to 6% in pasture-based systems. Targeted mitigation should address manure emissions in confinement systems, prefarm embedded, and fertilizer emissions in pasture-based systems, and enteric CH4 in both.

K. Nishimura, H. Hirabayashi, K. Kawashima et al.

ABSTRACT: Medium-chain fatty acids (MCFA) are rapidly utilized by the liver as an energy source. However, the effects of feeding MCFA to dairy cows during the transition period and the subsequent effect on postpartum performance is not clear. Therefore, the objective of this study was to evaluate the effects of MCFA supplementation on feed intake, rumen fermentation, blood profile, and milk production in dairy cows during their transition period. Twenty-one multiparity Holstein cows were randomly assigned to 2 dietary groups: one group received a diet supplemented with MCFA calcium salts (MCFA-Ca) from 3 wk relative to expected parturition to 5 wk postpartum (MCFA; n = 10), and the other group received the same diet without supplements (control; n = 11). Medium-chain fatty acid calcium salts containing 80% caprylic acid and 20% capric acid were added to the mixed diet at 1.5% DM. During the close-up period (from 3 wk relative to expected parturition until parturition), cows were fed a TMR with restricted intake to provide 100% of the metabolic energy requirement. Subsequently, the cows were fed a TMR ad libitum from parturition to 5 wk postpartum. Dry matter intake and BW did not differ throughout the experimental period between groups. Rumen fermentation and protozoa counts remained unaffected during the experimental period. Supplementation of MCFA had no effect on the plasma concentrations of nonesterified fatty acids and total ketone bodies in cows throughout the experimental period. Conversely, postpartum plasma glucagon concentration was higher in the MCFA group than in the control group, and milk yield tended to increase in the MCFA group. In conclusion, our results suggested that MCFA-Ca supplementation enhances the catabolic state by affecting pancreatic hormone secretion, resulting in an increase in milk yield during the fresh period without an excessive negative energy balance in dairy cows.

Anna Flynn, John Leech, Marie McFadden et al.

ABSTRACT: Colostrum quality is influenced by multiple factors, including its microbial load, which is determined by the cleanliness of collection and storage conditions. Additionally, the dam's diet and immune status play a crucial role in shaping colostrum quality by affecting IgG concentrations. Whereas many factors contribute to colostrum quality, this study will specifically use IgG content as the primary measure of quality. It is well established that feeding low-quality colostrum negatively affects calf health and growth, whereas feeding good-quality colostrum leads to better outcomes. However, it remains unclear if feeding colostrum above the recommended quality threshold offers additional benefits for calf health and growth. This study compared the effects of adequate- versus high-quality colostrum on dairy heifer calf growth, health, and the development of the fecal microbiome during the first 15 wk of life. We also measured the levels of apparent efficacy of absorption of IgG in both groups. Colostrum quality was initially determined and measured before feeding using a Brix refractometer (only feeding a minimum of 21% Brix); 93 heifer calves were assigned to treatment based on this data. Subsequently, laboratory analyses were conducted using radial immunodiffusion assays to measure the exact IgG levels in the colostrum; 72 calves were selected for continuation in the experiment based on the highest (n = 36) and lowest (n = 36) IgG levels in the colostrum. For these 72 calves, laboratory analyses were conducted using radial immunodiffusion assays to measure the exact IgG levels in the colostrum at the point of feeding and in the calf serum at 24 h after feeding. To ensure a fair comparison, the groups were balanced for calf birthweight, breed, and dam parity. Serum IgG at 24 h, weight, and health data were analyzed in SAS using linear mixed models and logistic regression. Alpha and β diversity were analyzed using R with ANOVA, permutational multivariate analysis of variance (PERMANOVA), and Benjamini-Hochberg P-value adjustments. Calves fed colostrum with a high IgG content (123.0 mg/mL IgG) exhibited higher rates of passive transfer compared with those fed adequate-quality colostrum (85.2 mg/mL IgG). Both groups had passive transfer rates >23 mg/mL IgG. Health outcomes were similar between the 2 groups, and ADG during the preweaning period was comparable, with calves gaining an average of 0.62 kg/d. Measures of α and β diversity in the fecal microbiome showed similar development in both groups. Apparent absorption efficacy was lower in calves fed high-quality colostrum (24.9%) compared with those fed adequate-quality colostrum (29.3%). The findings of this study support current recommendations for colostrum quality and suggest that calves may have a limited capacity to absorb higher concentrations of IgG. Whereas feeding higher-quality colostrum did not lead to significant improvements in growth, health, or microbiome diversity, it demonstrated that adequate-quality colostrum can be equally effective when combined with best practice management. Further research is needed to better understand the relationships between immunoglobulin absorption efficiency, calf health, microbiome development, and growth performance.

Bolong Fang, Yuzhi Li, Xiaole Zhao et al.

ABSTRACT: There is an urgent need for a rapid and sensitive method for the detection of Escherichia coli O157:H7, a class of hazardous foodborne pathogens in food safety. The traditional ELISA, a dominant rapid detection technique, has the disadvantage of low test sensitivity due to the insufficient enzyme loading capacity. In this study, we successfully synthesized self-assembled Au/polydopamine (PDA)/horseradish peroxide (HRP) nanocomposites with high enzyme loading on the outer surface and in the inner space. The high catalytic activity of Au/PDA/HRP was maintained by virtue of its hyperbranched flexible structure. For E. coli O157:H7 detection in milk samples, the proposed immunoassay achieved a visual cut-off value of 103 cfu mL−1 and a low limit of detection of 2.8 × 102 cfu mL−1, which are 33 and 46 times more sensitive than the traditional ELISA, respectively. The tremendous advantages of high sensitivity, excellent specificity, and adequate recovery make it promising for monitoring various kinds of pathogenic bacteria in food safety with greater sensitivity.

Hongqing Hu, Sébastien Franceschini, Pauline Lemal et al.

ABSTRACT: Negative energy balance (NEB) during early lactation is a critical physiological challenge in high-producing dairy cows, affecting both their health and production performance. The objectives of this study were: (1) to compare the genetic architecture of logit-transformed predicted NEB (LPNEB), a logit-transformed novel energy deficiency score (LEDS), 15 biomarkers, and 3 production traits using SNP-based genomic correlation analysis; (2) to extend this study to a chromosomal level to identify specific genomic regions involved in the regulation of energy metabolism; and (3) to compare the independent contributions of 8 traits to the underlying genetic architecture of LPNEB and LEDS. The SNP effects estimated from single-trait models can be used to quickly calculate genomic correlations for 20 traits. The results indicate strong genomic correlations between LPNEB and LEDS, as well as with key metabolic biomarkers, particularly blood nonesterified fatty acids (NEFA), highlighting their importance in energy metabolism. Furthermore, NEFA was a strong independent contributor to both LPNEB and LEDS. Chromosome regions located on BTA19 and BTA25 were identified as potentially associated with NEB. By combining genomic correlation and contribution analyses, this study provides valuable insights into the genetic basis of NEB and related traits in dairy cows.

Monika Małkowska-Kowalczyk, Justyna Żulewska, Danuta Kruk et al.

ABSTRACT: The aim of the study was to enquire to which extend 1H spin-lattice nuclear magnetic resonance (NMR) relaxometry data collected over a broad range of resonance frequencies (from 10 kHz to 10 MHz) have the potential to be used for assessing quality and authenticity of different categories of cheese. The following cheeses were selected mozzarella, processed cheese, pizza cheese, pizza cheese with modified fat phase), low-fat cheese, and long ripened cheese. The cheeses from 3 different production plants and various cheese production batches were used in the study. The samples from each group were subjected to instrumental composition analysis (FoodScan analyzer type 78810, FOSS, Hillerod, Denmark), water activity assessment (Aqualab 4TEV analyzer, type S40001855) and nuclear magnetic resonance relaxation dispersion study (SMARtracer FFC relaxometer, Stelar S.r.l, Italy). The state and dynamics of water present in products as free and bound water largely determines the properties of food products, including cheeses. Nuclear magnetic resonance relaxometry studies of cheese enable to reveal relaxation features characteristic of specific categories of cheese. Consequently, the studies can be treated as a step toward exploiting NMR relaxometry for accessing quality and authenticity of cheese. It was shown that at low resonance frequencies, the lower the moisture, the larger the relaxation rate. The durability and quality of cheeses depend on the presence and condition of water, so it is necessary to find a relationship between the presence, condition and mobility of water in cheeses, to increase and improve the quality and extend the shelf life.

T.C. Marques, H.F. Monteiro, D.B. Melo et al.

ABSTRACT: Rumen-protected choline (RPC) promotes benefits in milk production, immunity, and health in dairy cows by optimizing lipid metabolism during transition period management and early lactation. However, the RPC success in dairy cows depends on choline bioavailability, which is affected by the type of protection used in rumen-protected choline. Therefore, our objectives were to determine the effects of a novel RPC on dry matter intake (DMI), identify markers of metabolism and immunity, and evaluate lactation performance. Dry Holstein (n = 48) cows at 245 ± 3 d of gestation were blocked by parity and assigned to control or RPC treatment within each block. Cows enrolled in the RPC treatment received 15 g/d of CholiGEM (Kemin Industries, Cavriago RE, Italy) from 21 d prepartum and 30 g/d of CholiGEM from calving to 21 d postpartum. During the transition period, DMI was measured daily, and blood was sampled weekly for energy-related metabolites such as β-hydroxybutyrate (BHB), glucose, and nonesterified fatty acids (NEFA), as well as immune function markers such as haptoglobin (Hp) and lipopolysaccharide-binding protein (LPB). Vaginal discharge samples were collected at the calving and 7 d postpartum and stored in microcentrifuge tubes at −80°C until 16S rRNA sequencing. The main responses of body condition score, body weight, DMI, milk yield, milk components, and immune function markers were analyzed using the GLIMMIX procedure of SAS with the effects of treatment, time, parity, and relevant covariates added to the models. The relative abundance of microbiome α-diversity was evaluated by 3 indexes (Chao1, Shannon, and Simpson) and β-diversity by principal coordinate analysis and permutational multivariate ANOVA. We found no differences in DMI in the pre- and postpartum periods. Cows fed RPC increased the yields of energy- and 3.5% fat-corrected milk and fat yield in primiparous and multiparous cows, with an interaction between treatment and parity for these lactation variables. However, we found no differences in milk protein and lactose up to 150 DIM between treatments. Glucose, NEFA, and BHB had no differences between the treatments. However, RPC decreased BHB numerically (control = 1.07 ± 0.13 vs. RPC = 0.63 ± 0.13) in multiparous on the third week postpartum and tended to reduce the incidence of subclinical ketosis (12.7% vs. 4.2%). No effects for Hp and LPB were found in cows fed RPC. Chao1, Shannon, and Simpson indexes were lower at calving in the RPC treatment than in the Control. However, no differences were found 7 d later for Chao1, Shannon, and Simpson indexes. The vaginal discharge microbiome was altered in cows fed RPC at 7 d postpartum. Fusobacterium, a common pathogen associated with metritis, was reduced in cows fed RPC. Rumen-protected choline enhanced lactation performance and health and altered the vaginal discharge microbiome which is a potential proxy for uterine healthy in dairy cows. The current study's findings corroborate that RPC is a tool to support adaptation to lactation and shed light on opportunities for further research in reproductive health.

K.E. Schütz, B. Latimer, N. McDonald et al.

ABSTRACT: In countries with pasture-based dairy systems and relatively cold winters, such as New Zealand, it is common to manage pregnant, nonlactating cows on forage crop paddocks rather than pasture, due to slow pasture growth rates. Wintering dairy cattle on grazed crops can compromise welfare if wet and muddy underfoot conditions occur, which can reduce lying. This study investigated behavioral and physiological indicators of welfare of cows under 2 wintering practices: cows managed on and grazed kale crop (Brassica oleracea), and cows managed on pasture with baled hay. Following dry-off (d 0), 80 cows were randomly assigned to 1 of the 2 wintering practices (40 cows/practice) and monitored between d 4 and 32 (phase 1). During this period, lying and stepping behavior was continuously recorded using leg-based accelerometers. Blood samples were obtained at d 0 and 32 for measurements of thyroxine (T4), nonesterified fatty acids (NEFA), white blood cells (WBC), and red blood cells. All data for phase 1 were presented descriptively due to the lack of treatment replication. Daily mean air temperature during this period was 5.2°C (range: 0.0–10.7°C), and rainfall was 1.1 mm/d (range: 0–5.6mm/d). Between d 4 and 32, cows in both groups spent similar amounts of time lying (pasture with hay cows: 8.9 h/24 h ± 2.57, kale crop cows: 8.7 h/24 h ± 3.06, mean ± SEM). Both groups reduced their lying on wet and cold days, and there was evidence of rebound lying once unfavorable weather conditions stopped. Cows on kale crop had numerically higher NEFA and lower WBC compared with cows managed on pasture, although most physiological values were within normal ranges. In a second phase of the study (d 34 and 35), cows were managed under controlled, replicated conditions in the 2 wintering practices using typical on-farm stocking rates (2 or 4 cows per group in the pasture with hay and kale crop treatments, respectively; n = 10 groups/treatment). During this period, cow behavior, skin and surface temperatures, hygiene scores, feed intakes, and ground conditions were measured. Weather conditions during the 48-h exposure were mostly cold and dry (mean air temperature: 7.8°C, range: −2.2 to 20.5°C). Cows managed on pasture with hay spent more time lying down on the first day of exposure; however, this was likely due to less space being available to kale cows on this day. Cows managed on pasture with hay ruminated more than cows on kale crop on both days of observations (d 1: 37.9% vs. 30.9% of observations, d 2: 36.8% vs. 28.7% of observations for pasture with hay and kale crop groups, respectively) and were lying more often in postures indicative of greater thermal comfort. Cows managed on pasture with hay had higher skin and surface temperatures compared with cows on kale crop, whereas cows on kale crop had dirtier coats. Results suggest that opportunities for thermal comfort were greater for cows managed on pasture with hay bales, which may be due to increased rumination activities and more insulated lying areas.

T. Uyama, D.F. Kelton, E.I. Morrison et al.

ABSTRACT: The objective of this cross-sectional study was to determine associations between calf management practices, the number of antimicrobial treatments, and antimicrobial resistance in preweaning heifers on Canadian dairy farms. A composite of 5 fecal samples from preweaning calves was collected from 142 dairy farms in 5 provinces and analyzed for phenotypic antimicrobial susceptibility with the microbroth dilution method. Questionnaires were used to capture herd characteristics and calf management practices used on the farm. Calf treatment records were collected during the farm visits. Escherichia coli was isolated from all 142 fecal samples with the highest resistance to tetracycline (41%), followed by sulfisoxazole (36%), streptomycin (32%), chloramphenicol (28%), ampicillin (16%), trimethoprim-sulfamethoxazole (15%), ceftriaxone (4.2%), cefoxitin (2.8%), amoxicillin-clavulanic acid (2.1%), ciprofloxacin (2.1%), nalidixic acid (2.1%), azithromycin (1.4%), and gentamicin (1.4%). Multidrug resistance was observed in 37% of E. coli isolates. Three-quarters of farms used fresh colostrum as the most common type of colostrum fed to calves. Colostrum quality was checked on 49% of farms, but the transfer of passive immunity was only checked on 32% of farms in the last 12 mo. Almost 70% of farms used straw or hay or a combination as the bedding material for calves. Among the 142 farms, a complete set of calf records were collected from 71 farms. In a multivariable logistic regression model, farms with ≥1.99 to 32.57 antimicrobial treatments/calf-year were 3.2 times more likely to have multidrug resistant E. coli in calf feces compared farms with <1.99 antimicrobial treatments/calf-year. Farms using hay or straw beddings were 5.1 times less likely to have multidrug resistant E. coli compared with those with other bedding materials including shavings or sawdust. Bedding management practices on farms may need to be investigated to reduce the potential effect on disseminating multidrug resistant bacteria.

Z.P. Xue, X. Cu, K. Xu et al.

ABSTRACT: Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus are the main species used for yogurt preparation. Glutathione (GSH) can be synthesized by S. thermophilus and plays a crucial role in combating environmental stress. However, the effect of GSH biosynthesis by S. thermophilus on cocultured L. delbrueckii ssp. bulgaricus is still unknown. In this study, a mutant S. thermophilus ΔgshF was constructed by deleting the GSH synthase. The wild strain S. thermophilus ST-1 and ΔgshF mutants were cocultured with L. delbrueckii ssp. bulgaricus ATCC11842 by using Transwell chambers (Guangzhou Shuopu Biotechnology Co., Ltd.), respectively. It was proven that the GSH synthesized by S. thermophilus ST-1 could be absorbed and used by L. delbrueckii ssp. bulgaricus ATCC11842, and promote growth ability and stress tolerance of L. delbrueckii ssp. bulgaricus ATCC11842. The biomass of L. delbrueckii ssp. bulgaricus ATCC11842 cocultured with S. thermophilus ST-1 or ΔgshF (adding exogenous GSH) increased by 1.8 and 1.4 times compared with the biomass of L. delbrueckii ssp. bulgaricus ATCC11842 cocultured with S. thermophilus ΔgshF. Meanwhile, after H2O2 and low-temperature treatments, the bacterial viability of L. delbrueckii ssp. bulgaricus cocultured with S. thermophilus ΔgshF, with or without GSH, was decreased by 41 and 15% compared with that of L. delbrueckii ssp. bulgaricus cocultured with S. thermophilus ST-1. Furthermore, transcriptome analysis showed that the expression levels of genes involved in purine nucleotide and pyrimidine nucleotide metabolism in L. delbrueckii ssp. bulgaricus ATCC11842 were at least 3 times increased when cocultured with S. thermophilus (fold change > 3.0). Moreover, compared with the mutant strain ΔgshF, the wild-type strain ST-1 could shorten the fermented curd time by 5.3 hours during yogurt preparation. These results indicated that the GSH synthesized by S. thermophilus during cocultivation effectively enhanced the activity of L. delbrueckii ssp. bulgaricus and significantly improved the quality of fermented milk.

Shendong Zhou, Mengru Chen, Meijuan Meng et al.

ABSTRACT: Ketosis is a metabolic disease that often occurs in dairy cows postpartum and is a result of disordered lipid metabolism. Acetyl-coenzyme A (CoA) acetyltransferase 2 (ACAT2) is important for balancing cholesterol and triglyceride (TG) metabolism; however, its role in subclinical ketotic dairy cows is unclear. This study aimed to explore the potential correlation between ACAT2 and lipid metabolism disorders in subclinical ketotic cows through in vitro and in vivo experiments. In the in vivo experiment, liver tissue and blood samples were collected from healthy cows (CON, n = 6, β-hydroxybutyric acid [BHBA] concentration <1.0 mM) and subclinical ketotic cows (subclinical ketosis [SCK], n = 6, BHBA concentration = 1.2–3.0 mM) to explore the effect of ACAT2 on lipid metabolism disorders in SCK cows. For the in vitro experiment, bovine hepatocytes (BHEC) were used as the model. The effects of BHBA on ACAT2 and lipid metabolism were investigated via BHBA concentration gradient experiments. Subsequently, the relation between ACAT2 and lipid metabolism disorder was explored by transfection with siRNA of ACAT2. Transcriptomics showed an upregulation of differentially expression genes during lipid metabolism and significantly lower ACAT2 mRNA levels in the SCK group. Compared with the CON group in vivo, the SCK group showed significantly higher expression levels of peroxisome proliferator–activated receptor γ (PPARγ) and sterol regulator element binding protein 1c (SREBP1c) and significantly lower expression levels of peroxisome proliferator–activated receptor α (PPARα), carnitine palmitoyl-transferase 1A (CPT1A), sterol regulatory element binding transcription factor 2 (SREBP2), and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Moreover, the SCK group had a significantly higher liver TG content and significantly lower plasma total cholesterol (TC) and free cholesterol content. These results were indicative of TG and cholesterol metabolism disorders in the liver of dairy cows with SCK. Additionally, the SCK group showed an increased expression of perilipin-2 (PLIN2), decreased expression of apolipoprotein B, and decreased plasma concentration of very low–density lipoproteins (VLDL) and low-density lipoproteins cholesterol (LDL-C) by downregulating ACAT2, which indicated an accumulation of TG in liver. In vitro experiments showed that BHBA induced an increase in the TG content of BHEC, decreased content TC, increased expression of PPARγ and SREBP1c, and decreased expression of PPARα, CPT1A, SREBP2, and HMGCR. Additionally, BHBA increased the expression of PLIN2 in BHEC, decreased the expression and fluorescence intensity of ACAT2, and decreased the VLDL and LDL-C contents. Furthermore, silencing ACAT2 expression increased the TG content; decreased the TC, VLDL, and LDL-C contents; decreased the expression of HMGCR and SREBP2; and increased the expression of SREBP1c; but had no effect on the expression of PLIN2. These results suggest that ACAT2 downregulation in BHEC promotes TG accumulation and inhibits cholesterol synthesis, leading to TG and cholesterol metabolic disorders. In conclusion, ACAT2 downregulation in the SCK group inhibited cholesterol synthesis, increased TG synthesis, and reduced the contents of VLDL and LDL-C, eventually leading to disordered TG and cholesterol metabolism.

M.R. Chowdhury, R.G. Wilkinson, L.A. Sinclair

ABSTRACT: Reducing the dietary crude protein (CP) concentration can decrease the financial cost and lower the environmental impact of milk production. Two studies were conducted to examine the effects of reducing the dietary CP concentration on animal performance, nutrient digestibility, milk fatty acid (FA) profile, and nitrogen use efficiency (NUE; milk N/N intake) in dairy cows fed legume silage-based diets. Thirty-six multiparous Holstein-Friesian dairy cows that were 76 ± 14 (mean ± SD) days in milk and 698 ± 54 kg body weight were used in a 3 × 3 Latin square design in each of 2 studies, with 3 periods of 28 d. In study 1, cows were fed diets based on a 50:50 ratio of red clover to grass silage [dry matter (DM) basis] containing 1 of 3 dietary CP concentrations: high (H) = 175 g of CP/kg of DM; medium (M) = 165 g of CP/kg of DM; or low (L) = 150 g of CP/kg of DM. In study 2, cows were fed 175 g of CP/kg of DM with a 50:50 ratio of alfalfa to corn silage (H50) or 1 of 2 diets containing 150 g of CP/kg of DM with either a 50:50 (L50) or a 60:40 (L60) ratio of alfalfa to corn silage. Cows in both studies were fed a total mixed ration with a forage-to-concentrate ratio of 52:48 (DM basis). All diets were formulated to meet the MP requirements, except L (95% of MP requirements). In study 1, cows fed L ate 1.6 kg of DM/d less than those fed H or M, but milk yield was similar across treatments. Mean milk protein, fat, and lactose concentrations were not affected by diet. However, the apparent total-tract nutrient digestibility was decreased in cows fed L. The NUE was 5.7 percentage units higher in cows fed L than H. Feeding L also decreased milk and plasma urea concentrations by 4.4 mg/dL and 0.78 mmol/L, respectively. We found no effect of dietary treatment on the milk saturated or monounsaturated FA proportion, but the proportion of polyunsaturated FA was increased, and milk odd- and branched-chain FA decreased in cows fed L compared with H. In study 2, DM intake was 2 kg/d lower in cows receiving L50 than H50. Increasing the alfalfa content and feeding a low-CP diet (L60) did not alter DMI but decreased milk yield and milk protein concentration by 2 kg/d and 0.6 g/kg, respectively, compared with H50. Likewise, milk protein and lactose yield were decreased by 0.08 kg/d in cows receiving L60 versus H50. Diet had no effect on apparent nutrient digestibility. Feeding the low-CP diets compared with H50 increased the apparent NUE by approximately 5 percentage units and decreased milk and plasma urea concentrations by 7.2 mg/dL and 1.43 mmol/L, respectively. Dietary treatment did not alter milk FA profile except cis-9,trans-11 conjugated linoleic acid, which was higher in milk from cows receiving L60 compared with H50. We concluded that reducing CP concentration to around 150 g/kg of DM in red clover and grass or alfalfa and corn silage-based diets increases the apparent NUE and has little effect on nutrient digestibility or milk performance in dairy cows.

A.M.L. Madureira, J. Denis-Robichaud, T.G. Guida et al.

ABSTRACT: The objective of this observational study was to evaluate the relationship between genomic daughter pregnancy rate (GDPR) with reproduction parameters such as pregnancy at first artificial insemination (AI), pregnancy per AI, and pregnancy losses (PL). A total of 12,949 events from 3,499 Holstein cows were included. Cows were enrolled as nulliparous (n = 1,220), primiparous (n = 1,314), or multiparous (n = 965). Cows were bred either after a timed AI protocol, timed embryo transfer (ET), or spontaneous estrus. Most lactating cows were bred following a timed AI protocol based on estradiol and progesterone, and most nulliparous were artificially inseminated following estrus detection. Hair samples were collected from the tail switch and cows were genotyped using a SNP platform (Clarifide, Zoetis). Cows that were bred by timed AI were evaluated for estrous behavior using tail chalk. Tail chalk was applied on the head of the tail 2 d before timed AI and the chalk was evaluated at AI (no estrus: 100% of chalk remaining or ≥50% of chalk remaining; Estrus: <50% of chalk remaining). Pregnancy diagnosis was performed at d 32 and 60 after AI using ultrasonography, and the presence of a heartbeat was considered a positive diagnosis. Pregnancy loss was defined as a pregnant cow on d 32 that was nonpregnant on d 60. As GDPR increased, the odds of pregnancy at first AI increased [odds ratio (OR) = 1.28, 95% CI = 1.20–1.35], the odds of pregnancy per AI increased (OR = 1.31, 95% CI = 1.25–1.36), and the odds of PL decreased (OR = 0.66, 95% CI = 0.60–0.72). Most cows that were bred on the day of the timed AI demonstrated estrus (n = 6,075; 92.9%). The odds of demonstrating estrus on the day of timed AI increased as GDPR increased (OR = 1.31, 95% CI = 1.17–1.48). There was no interaction between GDPR and parity or breeding management for pregnancy at first AI, pregnancy per AI, and PL. In conclusion, the odds of pregnancy at first AI and pregnancy per AI increased as GDPR increased. Moreover, the odds of PL increased as GDPR decreased. Greater GDPR was also associated with greater occurrence of estrus on the day of timed AI. These results suggest that selecting for higher GDPR could result in better reproductive performance, but this would need to be assessed with additional research.

G.M. Pereira, B.J. Heins, B. Visser et al.

ABSTRACT: The objective of this study was to compare 3-breed rotational crossbred (CB) cows of the Montbéliarde, Viking Red, and Holstein (HO) breeds with HO cows fed 2 alternative diets for dry matter intake (DMI), fat plus protein production (CFP), body weight (BW), body condition score (BCS), feed efficiency, and residual feed intake (RFI) from 46 to 150 days in milk (DIM) during first lactation. The CB cows (n = 17) and HO cows (n = 19) calved from September 2019 to March 2020. Cows were fed either a traditional total mixed ration diet (TRAD) or a higher fiber, lower starch total mixed ration diet (HFLS). The HFLS had 21% more corn silage, 47% more alfalfa hay, 44% less corn grain, and 43% less corn gluten feed than the TRAD. The 2 diets were analyzed for dry matter content, crude protein, forage digestibility, starch, and net energy for lactation. The BW and BCS were recorded once weekly. Daily milk, fat, and protein production were estimated from twice monthly milk recording with random regression. Measures of efficiency were CFP per kilogram of DMI and DMI per kilogram of BW. The RFI from 46 to 150 DIM was the residual error from regression of DMI on milk energy, metabolic BW, and the energy required for change in BW. Statistical analysis of all variables included the fixed effects of diet, breed group, and the interaction of diet and breed group. The CB cows fed HFLS had less DMI (−12%) and lower DMI/BW (−14%) compared with the HO cows fed TRAD. For CFP, CB and HO cows were not different when fed TRAD or HFLS. Furthermore, the CB cows fed HFLS had higher BW (+50 kg) compared with HO cows fed HFLS. The CB cows fed TRAD had higher BCS than HO cows fed TRAD and HO cows fed HFLS (+0.46 and +0.62, respectively). The HO cows fed TRAD had more DMI (+14%) and lower CFP per kilogram of DMI (−12%) compared with the HO cows fed HFLS. In addition, mean RFI from 46 to 150 DIM was lower and more desirable for CB cows fed HFLS (−120.0 kg) compared with HO cows fed TRAD (85.3 kg). Dairy producers may feed either TRAD or HFLS to CB cows without loss of CFP.

Aya A. Muhammed Saeed, Alan A. Othman , Kaihan H. S. H Karim et al.

The study of heavy metals in the human diet is important due to their dual effects as either essential or toxic to the human body. In this study, we determined the concentration of selected heavy metals in common potato and corn chips brands in Iraq markets. Ten common brands were selected and analyzed for their concentrations of the studied heavy metals by ICP-MS. The results shown that the average heavy metals level in potato and corn chips in (mg kg-1±SD) were 2.68±0.67 and 2.96±3.00 for Mn, 4.64±1.99 and 5.82±5.45 for Fe, 0.29±0.33 and 1.36±0.95 for Cu and 2.84±1.26 and 6.26±1.67 for Zn respectively. Corn chips were found to contain higher heavy metals than potato chips. The daily consumption of heavy metals from potato and corn chips (20 g daily intake) is lower than the recommended level set by the World Health Organization and Food and Agriculture Organization. Also, Daily intake of these metals is lower than the oral suggested amount and the upper tolerable daily intake set by the US. The contamination risk for the Iraqi population especially children from heavy metals exposure by this study performs to be non-significant, emphasizing the need to conduct more studies and confirm examining of heavy metals in foodstuffs especially chips brands.

E. B. Forbes