Lactating Dairy Cows Research Articles

First identification of Bordetella bronchiseptica subclinical mastitis in a lactating dairy cow in New Zealand

ABSTRACT Case history A gland of a cow with a high somatic cell count (385,000 cells/mL at 116 days in milk) was enrolled in a therapeutic subclinical mastitis study following a positive pre-enrolment culture. One week later, the quarter was treated with 1 g of procaine penicillin on three occasions, 12 hours apart (Day 0 and 1). A further milk sample was obtained from the quarter on Days 6, 14, and 21 after initiation of treatment. Clinical findings Milk samples were submitted for routine bacteriological culture and matrix-assisted laser desorption/ionised time-of-flight mass spectrometry (MALDI-TOF) analysis. A Gram-negative motile rod was isolated from all samples which could not be speciated using the laboratory’s standard panel of biochemical tests. The isolates were identified by MALDI-TOF as Bordetella bronchiseptica. Whole genome sequencing and comparison with publicly available genomic sequences showed that the bovine isolate did not cluster with any previously published B. bronchiseptica sequences. Diagnosis Subclinical mastitis caused by infection with Bordetella bronchiseptica. Clinical relevance Only one other case report could be found of this organism being identified in milk samples. Greater use of advanced identification systems will likely increase the number of organisms identified from mastitic milk samples. Appropriate identification is important to aid decision-making as, given the response to therapy and laboratory findings, there is a poor likelihood of bacteriological cure with beta-lactam therapy for this organism.

Characterizing dry and early lactation dairy cow management practices in Wisconsin and Minnesota.

The non-lactation ("dry") period and first few weeks after calving are a crucial time in a dairy cow's life which can greatly impact her welfare and success within a herd. Additionally, cow-calf separation has become a controversial topic in dairy production and there is a knowledge gap regarding the time of calf removal from the cow on US dairy farms. A description of animal management practices during the dry period and early lactation can provide key information if recommended practices are being implemented and what can be changed to enhance the overall welfare of transition cows. The objective of this study was to characterize farmer-reported housing, management, and disease incidence of dairy cows from 60 d before to 30 d after calving on dairy farms in Wisconsin and Minnesota. Surveys were mailed to a random sample of 1,503 dairy producers in Wisconsin (n = 948) and Minnesota (n = 555). The survey included questions regarding farm demographics, cow management from 60 d before 30 d after calving, calf separation practices, and transition cow disease incidence. The response rate was 31% (466/1,503; Minnesota: n = 145, Wisconsin: n = 321) at the end of the 10 wk data collection period. Respondents had an average of 219.5 ± 712.3 (±SD) milking cows with a range of 2-12,000 milking cows. Cow management varied greatly between farms during the dry period and early lactation. The most common dry cow housing used was a close-up pen (38% of farms) and freestalls for both fresh (15.9%) and lactating cows (39.3%). Cows were moved into new pens 0 - 6 times (median = 2) during the 60 d before to 30 d after calving and approximately one quarter of farms (26%) moved cows into new pens twice. Removal of calves from the calving pen was most commonly reported to occur less than 1 h (16.7% of farms), 1.1 to 2 h (22.3%), and 2.1 to 12 h (39.5%) after birth. Calf removal from the calving pen was reported to occur sooner after birth on farms with larger herds and if cows remained in the calving pen for less time after calving. Dystocia was reported to occur at a greater incidence than other transition diseases (7.0% ± 7.4), followed by retained placenta (6.4% ± 6.5). The results of this survey provide evidence that recommended care practices, such as using a calving pen and not overstocking a fresh cow pen, are being provided to dry and early-lactation cows on many dairy farms in this region. However, animal-based measures would be required to assess if cows are in a good welfare state. Nonetheless, these results can help identify possible barriers to success and opportunities for improvement for the management and potential performance of dairy cows.

Transcriptomics reveals the regulatory mechanisms of circRNA in the muscle tissue of cows with ketosis postpartum.

The transition period from late pregnancy to early lactation in dairy cows involves significant metabolic changes to cope with the challenges related to energy metabolism. Muscle tissue, as the largest energy-metabolizing tissue in dairy cows, plays a crucial role in energy metabolism. Furthermore, circular RNAs (circRNAs) have been shown to play key roles in various biological events. However, the regulatory mechanisms of energy metabolism and muscle cells mediated by circRNAs in the muscle tissue of ketotic dairy cows remain unclear. Here, we identified a total of 5103 circRNAs in the muscle tissue of ketosis-affected cows. Among these, compared to healthy cows, 57 circRNAs were differentially expressed in the muscle tissue of ketosis-affected cows, with 39 upregulated and 18 downregulated. Functional enrichment analysis based on the source genes of circRNAs indicated that circ-30,628 is closely related to carbon metabolism, and circ-CoQ2 is associated with mitochondrial energy metabolism. Given the sponge effect of circRNAs on miRNAs, we further predicted the network relationships of downstream miRNAs and mRNAs of circ-30,628 and circ-CoQ2, and found that their downstream target genes are involved in signaling pathways such as MAPK, Wnt, FoxO, and autophagy, which is associated with the proliferation, differentiation, energy metabolism, oxidative stress, and mitochondrial function of muscle cells. In summary, these findings provide a theoretical basis for understanding the functions of circRNAs regulating energy metabolism in the muscle tissue of ketosis-affected cows, thereby reducing the accumulation of ketone bodies to prevent the occurrence of ketosis in dairy cows.

Effects of Dietary Coated Folic Acid and Folic Acid Addition on Lactation Performance, Rumen Fermentation, and Hepatic Lipid Content in Early Lactation Dairy Cows.

This study evaluated the influences of coated folic acid (CFA) and folic acid (FA) on lactation performance, apparent digestibility, rumen volatile fatty acid (VFA) production, blood metabolism, and hepatic lipid content in cows. A total of 140 Holstein cows were allocated to seven groups in a randomized block design. Cows in the control received no addition, those in the in low CFA (LCFA), medium CFA (MCFA), and high CFA (HCFA) groups received CFA at 135, 270, and 405 mg FA/d, and those in the low FA (LFA), medium FA (MFA), and high FA (HFA) groups received FA at 135, 270, and 405 mg/d. The experiment began 5 weeks before calving to 6 weeks after calving. When increasing the level of CFA, the fat-corrected milk (FCM), fat and protein yields, de novo fatty acid content, and feed efficiency increased linearly. A linear increase was observed for nutrient digestibility and ruminal total VFAs. The blood total protein, albumin, superoxide dismutase, glutathione peroxidase, and folate increased linearly, but blood non-esterified fatty acids and β-hydroxybutyric acid and hepatic lipids decreased linearly. When increasing the level of FA, the FCM and milk fat yields increased linearly, but the rumen total VFA increased quadratically. Compared with MFA, cows receiving MCFA had a greater milk yield and lower hepatic lipids. Overall, the addition of CFA increased the milk yield and decreased the hepatic lipid content in cows.

Biorefined perennial ryegrass press cake as an alternative feed for dairy cows in late lactation and during the dry period: a demonstration

Abstract To investigate the potential application of replacing a proportion of a perennial ryegrass (PRG) silage diet with press cake on productivity and enteric methane (CH4) emissions in late lactation and non-lactating spring-calving dairy cows, a study was undertaken in which control cows (n = 21) were offered PRG silage, while treatment cows (n = 21) were offered a diet consisting of 60% PRG press cake and 40% of the same PRG silage. Although treatment cows had higher group average dry matter intakes (DMI) and produced more enteric CH4, carbon dioxide (CO2), milk solids, protein, fat- and protein-corrected milk yield (FPCM) in late lactation, the magnitude of the difference between treatment and control cows varied from week to week (P < 0.050). When enteric CH4 per kg of milk yield, milk solids and FPCM were considered, there was no significant difference between treatment and control. Absolute enteric CH4 was higher for cows fed press cake during the non-lactating period but this tended to vary from week to week. Similarly, CO2 (P < 0.001) and hydrogen (H2; P = 0.023) differed from week to week for cows offered press cake, and cows offered PRG silage in the non-lactating period. Although there was no significant effect of diet on body weight (BW) and body condition score (BCS), when enteric CH4 was expressed on a per kg BW basis, cows offered press cake tended to produce more enteric CH4 in both late lactation and during the dry period.

Using Milk Urea to Evaluate Production, Efficiency of Nitrogen Utilization and Urinary Nitrogen Excretion During The Lactation In Dairy Cows

Abstract The aim of this study was to use milk urea to evaluate production parameters, efficiency of nitrogen utilization, and urinary nitrogen excretion during lactation in Holstein dairy cows. Cows in the 1st lactation phase compared to the 2nd and 3rd lactation phases showed: increase (P < 0.05) in daily milk yield; decrease (P < 0.05) in fat and protein content in milk; decrease in milk urea content (P < 0.05); with a lower individual number of animals (31% of dairy cows in the 1st stage of lactation, 39 % of dairy cows in the 2nd stage of lactation, and 44 % of dairy cows in the 3rd phase of lactation) with an above-limit milk urea content (35.0 ± 4.7; 34.9 ± 4.1, 34.8 ± 4.1 mg.dl-1); decreased urinary nitrogen excretion (P < 0.05); and efficiency of nitrogen utilization from feed to milk (P < 0.05). According to the phase of lactation, the efficiency of nitrogen utilization decreased and urinary nitrogen excretion increased with increasing milk urea content.

Endocrine adaptations to demanding physiological states in ruminants.

Highly productive ruminants rely on hormonally driven adaptations to prioritize the use of limiting nutrients during the demanding phases of the pregnancy-lactation cycle. Glucose, the predominant oxidative fuel of fetal life and the absolute precursor of mammary lactose synthesis, illustrates the need and benefit of such adaptations. Endocrine mechanisms such as insulin resistance and/or hypoinsulinemia favor the diversion of maternal glucose to the placenta or mammary gland where uptake is independent of insulin. Research in dairy cows in the 1980s and 1990s identified growth hormone as a peripherally acting signal opposing the effects of insulin. The following decades have seen the discovery of a new generation of signals secreted almost exclusively by adipose tissue, skeletal muscle or liver, dynamically regulated by metabolic challenges, and engaged in cross-organ communication. The understanding of these signals in the coordination of metabolism in ruminants has been limited by the availability of assays to measure their circulating concentrations and materials to perform functional studies. Nevertheless, emerging data point to their importance during demanding physiological states in ruminants, including early lactation in dairy cows and late pregnancy in sheep. Examples include modulation of insulin action by liver-derived fibroblast growth factor 21 (FGF21) and regulation of energy allocation among tissues by the action of the adipose-derived hormone leptin via its ability to control the hypothalamic-pituitary-thyroid axis. Recent studies investigating the regulation and action of FGF21 and leptin in dairy cows and sheep will be used to illustrate the potential of recently discovered signals to coordinate metabolism during physiologically demanding states such as early lactation.

Effect of the Lactation Phases on the Amplitude of Variation in Blood Serum Steroid Hormones and Some Hematochemical Analytes in Three Dairy Cow Breeds.

Lactation in dairy cows implies comprehensive endocrine and metabolic changes including a systemic electrolytic reaction. Previous studies have rarely considered these specific demands due to the influence of lactation periods. Therefore, this study aimed to assess the effects of early, middle, and late lactation phases on the dynamic changes in serum concentrations of progesterone (P4), 17β-oestradiol (E2), cortisol, and some electrolytes (Ca++, Mg++, Na+, K+, Cl-, Pi) and biochemical parameters (alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK), total bilirubin, urea, and iron (Fe++) in 10 Holstein, 10 Brown Swiss, and 10 Modicana multiparous healthy dairy cows (4.2 ± 1.7 years of age) sampled at 60-day intervals throughout lactation. Lactation induced significant changes in the concentrations of P4, which peaked at >120-180 days, decreased at >240-300 days, and increased again after 300 days. Cortisol showed an opposite trend to P4, with concentrations progressively decreasing, except for the phase between >240 and 300 days, and a steep drop at >300 days compared to previous phases. Na+ concentrations showed the lowest values at 0-60 d and the highest ones at >180-240 days, whereas Mg++ showed the highest values at >60-120 d and the lowest at >300 d. Significant correlations were found between P4 with cortisol, Cl- and K+, and cortisol with Ca++ and LDH. Significant differences in average concentrations of AST, ALT, LDH, Ca++, Mg++, and Fe++ were observed among different dairy cow breeds. Understanding the dynamic changes in hormone levels, electrolytes, and biochemical parameters during different lactation phases, while considering breed differences in dairy cows, is crucial for improving herd health management and milk production in commercial dairy farms.

Fermented soybean meal modified the rumen microbiota and increased the serum prolactin level in lactating Holstein cows.

This study aimed to investigate the effects of fermented soybean meal (FSM) on milk production, blood parameters, and rumen fermentation and microbial community in dairy cows. In this study, 48 healthy Holstein cows (parity, 3.0 ± 0.6; days in milk, 86.0 ± 6.7) were used. Cows were randomly assigned into four groups (CON, T-200, T-400, and T-600) with 12 cows per group. Cows in CON were not supplemented with FSM. Cows in T-200, T-400, and T-600 were supplemented with 200, 400, and 600 g/head/day FSM, respectively. This study lasted 5 weeks (1-week adaptation and 4-week treatment). The results showed that FSM did not affect milk yield and milk components (p > 0.05). In the serum, FSM greatly increased prolactin (p < 0.01), and a dosage effect was observed. Aspartate aminotransferase and total protein were the highest in the T-400 (p < 0.05), and triglycerides was the lowest in T-200 (p < 0.05), and there was no difference for the 3 measurements between the other 3 groups (p > 0.05). In the rumen, FSM did not affect pH, microbial crude protein, acetate, propionate, butyrate, valerate, total volatile fatty acids and the ratio of acetate:propionate (p > 0.05), only changed NH3-N, isobutyrate and isovalerate (p < 0.05). The results of the rumen bacterial 16S rRNA genes sequencing showed that FSM decreased the richness (p < 0.05) and evenness (p < 0.05) of the bacterial communities. PCoA analysis showed that FSH altered the rumen bacterial community (ANOSIM, R = 0.108, p = 0.002). In the relative abundance of phyla, FSM increased Firmicutes (p = 0.015) and Actinobacteriota (p < 0.01) and Patescibacteria (p = 0.012), decreased Bacteroidota (p = 0.024). In the relative abundance of genera, FSM increased Christensenellaceae R-7 group (p = 0.011), Lactococcus (p < 0.01), Candidatus Saccharimonas (p < 0.01), Olsenella (p < 0.01), decreased Muribaculaceae_norank (p < 0.01). Conclusively, supplemented FSM altered the rumen fermentation parameters and bacterial community, and increased serum prolactin level in lactating Holstein cows. These findings may provide an approach to keep the peak of lactation in dairy cows.

Assessing traditional and machine learning methods to smooth and impute device-based body condition score throughout the lactation in dairy cows

Regular monitoring of body condition score (BCS) changes during lactation is an essential management tool in dairy cattle; however, the current BCS measurements are often discontinuous and unevenly spaced in time. The imputation of BCS values is useful for two main reasons: i) achieving completeness of data is necessary to be able to relate BCS to other traits (e.g. milk yield and milk composition) that have been routinely recorded at different times and with a different frequency, and ii) having expected BCS values provides the possibility to trigger early warnings for animals with certain unexpected conditions. The contribution of this study was to propose and evaluate potential methods useful to smooth and impute device-based BCS values recorded during lactation in dairy cattle. In total, 26,207 BCS records were collected from 3,038 cows (9,199 and 14,462 BCS records on 1,546 Holstein and 1,211 Montbéliarde cows respectively, and the rest corresponded to other minority cattle breeds). Six methods were evaluated to predict BCS values: the traditional methods of test interval method (TIM), and multiple-trait procedure (MTP), and the machine learning (ML) methods of multi-layer perceptron (MLP), Elman network (Elman), long-short term memories (LSTM) and bi-directional LSTM (BiLSTM). The performance of each method was evaluated by a hold-out validation approach using statistics of the root mean squared error (RMSE) and Pearson correlation (r). TIM, MTP, MLP, and BiLSTM were assessed for the imputation of intermediate missing values, while MTP, Elman, and LSTM were evaluated for the forecasting of future BCS values. Regarding the machine learning methods, BiLSTM demonstrated the best performance for the intermediate value imputation task (RMSE = 0.295, r = 0.845), while LSTM demonstrated the best performance for the future value forecasting task (RMSE = 0.356, r = 0.751). Among the methods evaluated, MTP showed the best performance for imputation of intermediate missing values in terms of RMSE (0.288) and r (0.856). MTP also achieved the best performance for forecasting of future BCS values in terms of RMSE (0.348) and r (0.760). This study demonstrates the ability of MTP and machine learning methods to impute missing BCS data and provides a cost-effective solution for the application area.

A review of extended lactation in dairy cows managed in high-input and pasture-based farming systems

Traditionally the lactation cycle of a dairy cow is based around a 12-month calving interval, allowing for 10 months of lactation, followed by a 2-month dry period. This means that the cow has to conceive within 2–3 months after calving, when she is also at peak lactation and metabolically is in a negative energy balance. Such challenging physiological conditions make it challenging for the cow to conceive at this time and many modern high-producing cows fail to get pregnant within the constraints of a 12-month calving interval. In addition, many cows still produce at a high level at drying-off time, increasing the risk of intramammary infections. Therefore, delaying conception past peak production and, as a result, extending the lactation beyond 10 months may increasingly be necessary. Additionally, extended lactation (EL) may offer other advantages such as fewer calves being born and thus fewer ‘surplus’ calves needing to be culled at a young age, fewer health and welfare issues and improved environmental outcomes (i.e. less greenhouse-gas emission; less antibiotic usage) during the lifetime of the animal. Extending lactation is a straight forward management practice in high-input dairy systems where a consistent supply of feed supplements is readily available, but may be more challenging to implement in low(er)-input pasture-based systems. The latter are much more seasonal, with a 12-month calving interval allowing pasture growth and quality to match the cow’s nutritional demands; cows calve in spring when high-quality pasture is abundant and are dried-off during winter when pasture growth is more limited. In this review, we explored the impact of EL in both high-input systems and pasture-based systems. It covers the effects of EL on milk production, composition and processing, as well as on reproductive performance, health and welfare, and environmental and economic outcomes.

Effect of feeding two types of concentrates in morning and evening meals and two types of fat supplement on diurnal patterns of plasma parameters in lactation dairy cows

The diurnal patterns of feed intake and TMR composition influence blood parameters in dairy cows; however, the effect of feeding TMR with different compositions in the morning and evening meals is not well characterized. In a completely random design, forty Holstein cows (110 ± 30 days postpartum) were randomly assigned to four treatment groups, with 10 cows per treatment. The treatments were as follows: a base diet containing 50 % cereal starch from barley grain and 50 % cereal starch from corn grain in the morning and evening meal + either prilled fatty acids supplement (EqP) or calcium salts of fatty acids supplement (EqCS); a base diet containing 25 % cereal starch from barley grain, 75 % cereal starch from corn grain in the morning meal, and 75 % cereal starch from barley grain and 25 % cereal starch from corn grain in the evening meal + either prilled fatty acids supplement (DiP) or calcium salts of fatty acids supplement (DiCS). Dry matter intake was affected by treatments (P ˂ 0.01). The highest intake was observed for EqP, EqCS, DiP,and DiCS. 3.5 % fat-corrected milk and milk fat percentage was significantly higher for EqP than other treatments (P ˂ 0.01), but other milk components were not significantly different among treatments (P ˃ 0.05). A significant difference was observed for glucose, cholesterol, TG, AST, and insulin concentration among treatments (P ˂ 0.01). The concentrations of all plasma parameters (glucose, cholesterol, TG, BUN, AST, insulin, and NEFA) significantly changed over 24-h period (P ˂ 0.01). Plasma concentrations of glucose, cholesterol, TG, BUN, AST, insulin, and NEFA displayed a treatment-by-time interaction (P ˂ 0.01). In general, changes in the cereal starch ratio (corn and barley) in TMR in each meal during a day affect the 24-h concentration of plasma parameters, but there was no strong evidence of leverage for cows’ metabolism.

Epidemiology of antimicrobial resistance in commensal E. coli from healthy dairy cattle on a Mediterranean pasture-based system of Australia: A cross-sectional study

This study aimed to determine the prevalence of antimicrobial resistance (AMR) in commensal E. coli from healthy lactating cows and calves in the Mediterranean pasture-based feeding dairy system of Western Australia (WA). Fecal samples were collected from healthy adult lactating cows and healthy calves from dairy farms in WA. Presumptive commensal E. coli was isolated from these samples and confirmed using matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Broth microdilution was used to assess the prevalence and the phenotypic AMR profiles of the E. coli isolates to 8 antimicrobial agents of dairy industry and human importance. The minimum inhibitory concentration (MIC) for each isolate was interpreted using the Epidemiologic Cutoff (ECOFF) and Clinical and Laboratory Standards Institute (CLSI) breakpoints. Genomic characterization provided multi-locus sequence types and AMR genes for a selection of isolates categorised as non-wild type (NWT) by ECOFF values for the combination of ampicillin, trimethoprim-sulfamethoxazole, and tetracycline. From a total of 1,117 fecal samples (633 adult, 484 calf) collected across 26 randomly selected farms, 891 commensal E. coli isolates were recovered (541 adult, 350 calf). Commensal E. coli classified as NWT was highest for ampicillin for both adult (68.8%; 95% CI = 64.7 - 72.7) and calf feces (67.1%; 95% CI = 62.0 - 72.0). A large proportion of tetracycline NWT and trimethoprim-sulfamethoxazole NWT organisms were also identified from calf feces, being 44.0% (95% CI = 38.7 - 49.4) and 24.6% (95% CI = 20.2 - 29.4) respectively. Clinical resistance prevalence was low, being higher for calves than for adult feces (ampicillin (adult: 7.8% (95% CI = 5.7 - 10.3); calf: 30.0% (95% CI = 25.2 - 35.1), tetracycline (adult: 6.3% (95% CI = 4.4 - 8.7); calf: 40.3% (95% CI = 35.1 - 45.6), and trimethoprim-sulfamethoxazole (adult: 2.6% (95% CI = 1.4 - 4.3); calf: 22.0% (95% CI = 17.7 - 26.7)). Commensal E. coli originating from calf feces was significantly higher in NWT prevalence compared with adult feces for ciprofloxacin (P = 0.023), gentamicin (P = 0.02), tetracycline (P < 0.001), and trimethoprim-sulfamethoxazole (P < 0.001). The overall number of antimicrobials an isolate was classified as NWT toward varied among farms and was significantly higher for isolates originating from calf than adult feces (P < 0.001). The strain type and sampling source of the commensal E. coli investigated were both associated with the commonality of the resultant resistance genome. Clinical resistance and NWT classification were highest for ampicillin, tetracycline, and trimethoprim-sulfamethoxazole, all antimicrobials commonly used in the treatment of dairy cattle in Australia. Though highly variable across farms, commensal E. coli isolated from healthy dairy calf feces had significantly higher NWT and multidrug resistance (MDR) prevalence compared with feces from healthy adult lactating dairy cows. The resistant genome identified in MDR isolates, though not always consistent with the phenotype, included QnrS1 and genes encoding AmpC β-lactamase and aminoglycoside phosphotransferase.

Supplementation of isoacids to lactating dairy cows fed low or high forage diets: Effects on performance, digestibility, and milk fatty acid profile

Our objective was to determine the effects of isoacids (ISO) on the lactation performance, digestibility, and milk fatty acid (FA) profile of Holstein cows fed 2 forage NDF levels (FL). The study was 10-wk long (including 2-wk for covariate) utilizing a randomized complete block design. Sixty-four mid-lactating Holstein cows [662 ± 71 kg BW, 119 ± 51 DIM, 2 ± 0.9 parity] were blocked by parity, DIM, and prior milk yield (MY) for multiparous cows or genetic merit for primiparous cows, and randomly assigned to 1 of the 4 diets (n = 16). Diets were arranged as a 2 × 2 factorial, with 2 FL containing 21 (HF) and 17% forage NDF (LF) without (WIA) or with ISO supplementation (IA, 7.85 mmol/kg DM and 3.44 mmol/kg DM for isobutyrate and 2-methylbutyrate, respectively). Diets were balanced for similar NEL (1.58 Mcal/kg DM), CP (16.0%) and total NDF (27.2%). Feed intake and MY were recorded daily. Nutrient digestibility for each cow was determined using indigestible NDF as a marker, and fecal samples were collected at 8-time points (4 h intervals between samples). Individual cow milk samples composited over a 10-wk period were analyzed using gas chromatography for FA profile. The statistical model included FL, ISO, and FL × ISO as fixed effects and block as a random effect (lme4 in R). The ISO did not affect DMI (P = 0.13), while LF had greater DMI than HF diets (27.8 vs. 26.0 kg/d; P < 0.01). However, ISO increased MY (34.7 vs. 37.2 kg/d; P < 0.01) and ECM (41.9 vs. 39.0 kg/d; P < 0.01) by 7% in HF but not in the LF diet, suggesting FL × ISO interaction (P = 0.04). Interestingly, ISO increased ADG (0.4 kg/d) but decreased MUN by 9% only in LF diet as indicated by FL × ISO interaction (P < 0.01). Additionally, ISO increased DM, OM, NDF, and CP digestibility by 10-24% in HF (P < 0.01), but not in LF (FL × ISO; P > 0.05). As expected, ISO increased milk odd chain FA profiles in the IA groups irrespective of FL, e.g., the IA had greater C15:0 (1.87 vs. 1.54 g/100g FA; P = 0.03) and a tendency to be greater C17:0 levels (0.86 vs. 0.76 g/100g FA; P = 0.05) compared with WIA groups. Overall, ISO improved MY and nutrient digestibility in the HF whereas it increased ADG and decreased MUN in LF diet. Additionally, ISO increased milk odd chain FA (C15:0 and C17:0) regardless of FL.

PSVIII-6 Effect of adding plant extracted saponin (PES) on accumulative gas production kinetics and methane emission of the prairie blend pelleted feed products in ruminant system

Abstract The objectives of this study were to study the effect of adding plant extracted saponin (PES) as phytochemical feed additive on in vitro accumulative gas production kinetics and methane (CH4) emission of blend pelleted feed products in ruminant system. Four levels of PES (0, 1, 2, 3%) were added to canola meal and pea mixtures with two different ratios (CMP1: 50:50; CMP2: 70:30) which were used to make Prairie blend pellet feed products. The accumulative gas production kinetics and CH4 were determined using in vitro systems. Ruminal fluid for in vitro studies was obtained from rumen fistulated lactation dairy cows. The experimental design was a randomized complete block design with the PES level as a fixed effect and in vitro run with fistulated animals as a random effect. The data were analyzed using Mixed Model Procedure of SAS. Polynomial contract was used to determine linear and quadratic relationship. The results showed that adding PES did not significantly affect the asymptotic production (a) with an average of 104.06 ± 12.38 (SD) mL/g DM, the gas production fractional rate (c) with an average of 1.00 ± 0.90 %/h, the average production at one-half of asymptotic production (AP) with an average 11.26 ± 0.87 mL and lag time with an average of 2.08 ± 0.81 h. As to CH4 emission at different incubation times, the result showed that at short incubation times (2 h, 4 h, 12 h), adding PES showed numerically reduced CH4 from 277 to 1.08 mL/g (at 2 h) and 4.39 to 1.59 mL/g (at 4 h). With increasing PES level, CH4 was significantly linearly reduced (P = 0.019) from 8.31 to 6.30 mL/g at 12h incubation time. At long incubation (24 h), adding PES did not have significant impact on CH4. In conclusion, adding PES at the studied levels to Prairie blend pellet feed products did not significantly affect accumulative gas production kinetics but it had a high potential to decrease CH4 emission at short incubation times.

499 Effect of adding plant extracted hydrolysable tanning and saponin combination to prairie blend pelleted feed products on accumulative gas production kinetics and methane emission in ruminant systems

Abstract The objectives of this study were to study the effect of adding plant extracted hydrolysable tanning (HT) and saponin (S) combination as a combined phytochemical feed additive (HTS) on in vitro accumulative gas production kinetics and methane (CH4) emission of blend pelleted feed products in ruminant systems. Four combination levels [0 (control), 1.5 (1% HT + 0.5% S), 3 (2% HT + 1%S), 4.5 (3% HT + 1.5% S)] were added to canola meal and pea mixtures with two different ratios (CMP1: 50:50; CMP2: 70:30) which were used to make Prairie blend pellet feed products. The accumulative gas production kinetics and CH4 were determined using in vitro systems. The ruminal fluid was obtained from rumen fistulated lactation dairy cows. The experimental design was a randomized complete block design with the HTS level as a fixed effect and in vitro run with fistulated animals as a random effect. The data were analyzed using SAS Mixed Procedure. Polynomial contract was used to determine linear and quadratic relationship. The results showed that adding HTS level linearly reduced asymptotic production a) from 110.5 to 82.7 mL/g DM (P = 0.043) and average production at one-half of asymptotic production (AP) from 11.9 to 9.5 mL (P = 0.069) without significantly affecting gas production fractional rate (c, %/h) with an average of 0.58 ± 0.49 %/h and lag time with an average of 1.95 ± 0.50 h. As to CH4 emission at different incubation times, the result showed that at short incubation times (2 h, 4 h, 12 h), adding HTS had numerically reduced methane emission (CH4) from 2.77 to 0.98 mL/g (at 2 h) and 4.39 to 1.38 mL/g (at 4 h). with increasing HTS level, CH4 was significantly quadratically reduced (P = 0.028) at 12 h incubation time from 8.31 to 5.76 mL/g. After long incubation (24 h), adding HTS did not have significant impact on CH4. In conclusion, adding HTS to prairie blend pellet feed products significantly affected gas production kinetics (the asymptotic production and average production at one-half of asymptotic production). Adding HTS had an increased potential to decrease CH4 emission at short incubation times.

Impact of heat stress during close-up dry period on performance, fertility and immunometabolic blood indices of dairy cows: prospective cohort study

This study aimed to investigate whether heat stress, as defined by the temperature-humidity index (THI) during the close-up dry period, had any impact on the productive performance, fertility, and immunometabolic blood indices of dairy cows in the subsequent lactation. Lactation performance was associated with increasing THI values on − 21, − 14, and − 7 d before calving resulting in decreased milk yield by about 2.30, 2.60, and 2.90 kg, respectively. The THI on the − 7 d before the calving was negatively associated with fertility parameters such as delayed first estrus postpartum, an elongated calving interval by approximately 32 d, a higher number of services per conception by 1.00, and an elongated artificial insemination service period, days open, and inter-calving period by about 20, 52, and 52 d, respectively. The study found that the immunometabolic blood indices were associated with increasing THI values during the close-up dry period. The study showed that exposing dairy cows to close-up dry period heat stress had negative consequences on performance, fertility, and immunometabolic blood indices in the subsequent lactation. Therefore, it is recommended that herd management and barn microclimate changes be implemented earlier, starting from the late dry period, to mitigate the negative impact of heat stress.

Longitudinal characterization of the muscle metabolome in dairy cows during the transition from lactation cessation to lactation resumption

Skeletal muscle is vital in maintaining metabolic homeostasis and adapting to the physiological needs of pregnancy and lactation. Despite advancements in understanding metabolic changes in dairy cows around calving and early lactation, there are still gaps in our knowledge, especially concerning muscle metabolism and the changes associated with drying off. This study aimed to characterize the skeletal muscle metabolome in the context of the dietary and metabolic changes occurring during the transition from the cessation of lactation to the resumption of lactation in dairy cows. Twelve Holstein dairy cows housed in tie stalls were dried off 6 weeks (wk) before the expected calving date. Cows were individually fed ad libitum total mixed rations composed of grass silage, corn silage, and concentrate during lactation and of corn silage, barley straw, and concentrate during the dry period. The metabolome was characterized in skeletal muscle samples (M. longissimus dorsi) collected on wk -7 (9 d before dry-off), -5 (6 d after dry-off), and wk -1, and 1 relative to calving. The targeted metabolomics approach was conducted using the MxP Quant 500 kit (Biocrates Life Sciences AG) with liquid chromatography, flow injection, and electrospray ionization triple quadrupole mass spectrometry. Statistical analysis on the muscle metabolite data was performed using MetaboAnalyst 5.0, which allowed us to conduct various multivariate analyses such as principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), informative heat map generation, and hierarchical clustering. The statistical analysis revealed a clear separation between pregnancy (wk -7, -5, and -1) and post-calving (wk 1). Starting 5 wk before calving and continuing through the first wk thereafter, the concentration of 3-methylhistidine (3-MH) in the muscle increased. This coincided with an increase in the concentrations of 11 AA (Phe, His, Tyr, Trp, Arg, Asn, Leu, Ile, Gly, Ser, and Thr) in the first wk after calving, whereas Gln decreased. l-arginine pathway metabolites (homoarginine, ornithine, citrulline, and asymmetric dimethylarginine), betaine, and sarcosine followed a similar pattern, increasing from wk -7 to -5, but decreasing from wk -1 to 1. The transition from pregnancy to lactation was associated with an increase in concentrations of the long-chain acylcarnitine species C16, C16:1, C18, and C18:1 in the muscle, whereas the concentrations of phosphatidylcholine and sphingomyelin in the muscle remained stable. The significant changes observed in the metabolome mainly concerned the AA and AA-related metabolites, indicating muscle protein breakdown in the first wk after calving. The metabolites produced by the L-Arg pathway might contribute to regulating skeletal muscle mass and function in periparturient dairy cows. The elevated concentrations of long-chain acylcarnitine species in the muscle in the first wk after calving suggest incomplete fatty acid oxidation, likely due to insufficient metabolic adaptation in response to the fatty acid load around the time of calving.

Prediction of body condition score throughout lactation by random regression test-day models.

Regular monitoring of body condition score (BCS) changes during lactation is a crucial management tool in dairy cattle; however, the current BCS measurements are often discontinuous and unevenly spaced in time. The aim of this study was to investigate the ability of random regression test-day models (RR-TDM) to predict BCS for the entire lactation in dairy cows even if the actual scoring is limited to one BCS record. The data consisted of test-day records of milk yield (MY), fat percentage (FP), protein percentage (PP) and BCS (based on a 9-point scale with unit increments; 1-9) collected from 2014 to 2022 in 128 herds in the Walloon Region of Belgium. In total, 20,698 test-day records on 2166 first-parity Holstein cows (2-12 with an average of 9.42 test-day records per cow) were available for MY, FP and PP; and 7985 records on the same animals (2-12 with an average of 3.68 records per cow) were available for BCS. To estimate the solutions, only one randomly selected BCS record per animal along with all her MY, FP and PP records were used, which were then used to predict BCS data (calibration set). The remaining BCS (1-11 with an average 2.86 BCS records per animal) were used to evaluate the goodness of the predictions (validation set). Multiple-trait RR-TDM was used to estimate (co)variance components through the average information restricted maximum likelihood (AI-REML) algorithm. Predicted BCS were grouped into nine classes as the original observed BCS used for comparison. Pearson correlation between the predicted and observed BCS, prediction error (PE), absolute prediction error (APE) and root mean squared prediction error (RMSE) were calculated. Mean (standard deviation; SD) BCS was 4.97 (1.01), 4.95 (1.07) and 4.98 (1.00) BCS units in the full, calibration and validation datasets, respectively. Pearson correlation between the observed and predicted BCS was 0.71, mean (SD) PE was 0.04 (0.52) BCS units, mean (SD) APE was 0.48 (0.53) BCS units and RMSE was 0.72 BCS units. These findings demonstrate the ability of RR-TDM to predict BCS for the entire lactation using a single BCS record along with available test-day records of milk yield and composition in Holstein dairy cows.

Performance of grazing cows fed supplements from coproducts of biodiesel industry replacing soybean meal.

The objective of the present study was to evaluate the substitution of soybean meals by biodiesel co-products on the performance and nutrient balance of lactating cows on pasture. Twelve dairy cows (7/8 Holstein-Gir) in early lactation were included in this feeding trial. These animals had an average daily milk yield of 21.1kg and were distributed in a 4 × 4 triple Latin square experimental design. Protein supplements fed to these lactating cows contained peanut meal, cotton and sunflower as a complete replacement for soybean meal. Nutrient intake and digestibility, milk production, microbial protein synthesis, energy and protein balance were the parameters assessed in this study. Supplements containing different biodiesel co-products did not influence (P > 0.05) the level of forage intake, supplementation and nutrient by lactating cows, except for the total digestible nutrients (TDN) intake which was higher (P ≤ 0.05) in cows supplemented with cottonseed meal. The cotton meal also promoted higher digestibility of TDN (P = 0.001) and total carbohydrates (TCHO; P = 0.001) of the diet and, as a result, higher energy consumption (P = 0.01) and lower negative energy balance (P = 0.01). Cottonseed meal is a co-product of the biodiesel industry that has the ability to replace soybean meal as a source of protein in the supplement without affecting performance and promoting greater energy availability, demonstrating its ability to reduce the effects of negative energy balance in cows at the beginning of lactation kept on tropical pastures.