Energy-corrected Milk Research Articles

An integrated microbiome- and metabolome-genome-wide association study reveals the role of heritable ruminal microbial carbohydrate metabolism in lactation performance in Holstein dairy cows.

Despite the growing number of studies investigating the connection between host genetics and the rumen microbiota, there remains a dearth of systematic research exploring the composition, function, and metabolic traits of highly heritable rumen microbiota influenced by host genetics. Furthermore, the impact of these highly heritable subsets on lactation performance in cows remains unknown. To address this gap, we collected and analyzed whole-genome resequencing data, rumen metagenomes, rumen metabolomes and short-chain fatty acids (SCFAs) content, and lactation performance phenotypes from a cohort of 304 dairy cows. The results indicated that the proportions of highly heritable subsets (h2 ≥ 0.2) of the rumen microbial composition (55%), function (39% KEGG and 28% CAZy), and metabolites (18%) decreased sequentially. Moreover, the highly heritable microbes can increase energy-corrected milk (ECM) production by reducing the rumen acetate/propionate ratio, according to the structural equation model (SEM) analysis (CFI = 0.898). Furthermore, the highly heritable enzymes involved in the SCFA synthesis metabolic pathway can promote the synthesis of propionate and inhibit the acetate synthesis. Next, the same significant SNP variants were used to integrate information from genome-wide association studies (GWASs), microbiome-GWASs, metabolome-GWASs, and microbiome-wide association studies (mWASs). The identified single nucleotide polymorphisms (SNPs) of rs43470227 and rs43472732 on SLC30A9 (Zn2+ transport) (P < 0.05/nSNPs) can affect the abundance of rumen microbes such as Prevotella_sp., Prevotella_sp._E15-22, Prevotella_sp._E13-27, which have the oligosaccharide-degradation enzymes genes, including the GH10, GH13, GH43, GH95, and GH115 families. The identified SNPs of chr25:11,177 on 5s_rRNA (small ribosomal RNA) (P < 0.05/nSNPs) were linked to ECM, the abundance alteration of Pseudobutyrivibrio_sp. (a genus that was also showed to be linked to the ECM production via the mWASs analysis), GH24 (lysozyme), and 9,10,13-TriHOME (linoleic acid metabolism). Moreover, ECM, and the abundances of Pseudobutyrivibrio sp., GH24, and 9,10,13-TRIHOME were significantly greater in the GG genotype than in the AG genotype at chr25:11,177 (P < 0.05). By further the SEM analysis, GH24 was positively correlated with Pseudobutyrivibrio sp., which was positively correlated with 9,10,13-triHOME and subsequently positively correlated with ECM (CFI = 0.942). Our comprehensive study revealed the distinct heritability patterns of rumen microbial composition, function, and metabolism. Additionally, we shed light on the influence of host SNP variants on the rumen microbes with carbohydrate metabolism and their subsequent effects on lactation performance. Collectively, these findings offer compelling evidence for the host-microbe interactions, wherein cows actively modulate their rumen microbiota through SNP variants to regulate their own lactation performance. Video Abstract.

Association of Lameness Prevalence and Severity in Early-Lactation Cows with Milk Traits, Metabolic Profile, and Dry Period

This study investigated the prevalence and severity of lameness in dairy cow herds, focusing on its relationship with milk traits, metabolic profile, and dry period management. Lameness was evaluated in 4221 multiparous Holstein dairy cows during early lactation (up to 60 days postpartum) using a 1-to-5 scale. The average lameness score was 1.67, with a prevalence of 10.66% (scores 3 to 5) and 4.55% classified as severe (scores 4 to 5). Severe lameness was associated with energy-corrected milk losses of −11.00 kg/day (p &lt; 0.001) and a decrease in milk lactose concentration by −0.16 percentage points (p &lt; 0.001), alongside a rise in somatic cell scores by +0.11. The incidence of cows with a milk fat-to-protein ratio below 1.2 increased by 21.7 percentage points, while those with a ratio above 1.4 rose by 19.1 percentage points as lameness worsened. Additionally, non-esterified fatty acid concentrations increased by 1.46 times as lameness severity intensified (p &lt; 0.001). Cows without lameness had blood cortisol levels 1.86 times lower than affected cows, with cortisol tripling in those with the highest scores. A dry period of 30 to 60 days was correlated with more healthy cows, whereas periods over 90 days resulted in 1.586 times higher odds of lameness (p &lt; 0.05). This research underscores the need for improved management strategies to enhance dairy cow welfare and productivity.

Genomic evaluation of residual feed intake in US Holstein cows: insights into lifetime feed efficiency

Residual feed intake (RFI) is an important trait of feed efficiency that has been increasingly considered in the breeding objectives for dairy cattle. The objectives of this study were to estimate the genetic parameters of RFI and its component traits, namely, dry-matter intake (DMI), body weight (BW), and energy-corrected milk (ECM), in lactating Holstein cows; we thus developed a system for genomic evaluation of RFI in lactating Holstein cows and explored the associations of the RFI of heifers and cows. The RFI values were calculated from 2,538 first (n = 2,118) and second (n = 420) lactation Holsteins cows between 2020 and 2024 as part of the STgenetics EcoFeed® program. Of the animals, 1,516 were heifers from the same research station with previously established RFI values . After quality control, 61,283 single-nucleotide polymorphisms were used for the analyses. Univariate analyses were performed to estimate the heritabilities of RFI and its components in lactating cows; bivariate analyses were then performed to estimate the genetic correlations between the RFI of heifers and lactating cows using the genomic best unbiased linear prediction method. Animals with phenotypes and genotypes were used as the training population, and animals with only genotypes were considered the prediction population. The reliability of breeding values was obtained by approximation based on partitioning a function of the accuracy of the training population’s genomic estimated breeding values (GEBVs) and magnitudes of genomic relationships between the individuals in the training and prediction populations. The heritability estimates (mean ± SE) of the RFI, DMI, ECM, and BW were 0.43 ± 0.07, 0.44 ± 0.04, 0.40 ± 0.05, and 0.46 ± 0.04, respectively. The average reliability of the GEBVs for RFI from the training and prediction populations were 44% and 30%, respectively. The genetic correlations for the RFI were 0.42 ± 0.08 between heifers and first lactation cows and 0.34 ± 0.06 between heifers and first and second lactation cows. Our results show that the genetic components of RFI are not fully carried over from heifers to cows and that there is re-ranking of the individuals at different life stages. Selection of animals for feed efficiency on a lifetime basis thus requires accounting for the efficiencies during animal growth and milk production as a lactating cow.

Genomic Prediction and Genome-Wide Association Studies for Productivity, Conformation and Heat Tolerance Traits in Tropical Smallholder Dairy Cows.

Genomic selection (GS) and genome-wide association studies (GWAS) have not been investigated in Vietnamese dairy cattle, even for basic milk production traits, largely due to the scarcity of individual phenotype recording in smallholder dairy farms (SDFs). This study aimed to estimate heritability (h2) and test the applicability of GS and GWAS for milk production, body conformation and novel heat tolerance traits using single test day phenotypic data. Thirty-two SDFs located in either the north (a lowland vs. a highland) or the south (a lowland vs. a highland) of Vietnam were each visited for an afternoon and the next morning to collect phenotype data of all lactating cows (n = 345). Tail hair from each cow was sampled for subsequent genotyping with a 50K SNP chip at that same visit. Milk production traits (single-test day) were milk yield (MILK, kg/cow/day), energy corrected milk yield adjusted for body weight (ECMbw, kg/100 kg BW/day), fat (mFA, %), protein (mPR, %) and dry matter (mDM, %). Conformation traits were body weight (BW, kg) and body condition score (BCS, 1 = thin to 5 = obese). Heat tolerance traits were panting score (PS, 0 = normal to 4.5 = extremely heat-stressed) and infrared temperatures (IRTs, °C) at 11 areas on the external body surface of the cow (inner vulval lip, outer vulval surface, inner tail base surface, ocular area, muzzle, armpit area, paralumbar fossa area, fore udder, rear udder, forehoof and hind hoof), assessed by an Infrared Camera. Univariate linear mixed models and a 10-fold cross-validation approach were applied for GS. Univariate single SNP mixed linear models were applied for the GWAS. Estimated h2 (using the genotype information to build relationships among animals) were moderate (0.20-0.37) for ECMbw, mFA, mPR, mRE, BW, BCS and IRT at rear udder; low (0.08-0.19) for PS and other IRTs; and very low (≤ 0.07) for MILK, ECM and mDM. Accuracy of genomic estimated breeding values (GEBVs) was low (≤ 0.12) for MILK, ECM, mDM and IRT at hind hoof; and moderate to high (0.32-0.46) for all other traits. The most significant regions on chromosomes (BTA) associated with milk production traits were 0.47-1.18 Mb on BTA14. Moderate to high h2 and moderate accuracies of GEBVs for mFA, mPR, ECMbw, BCS, BW, PS and IRTs at rear udder and outer vulval surface suggested that GS using single test day phenotypic data could be applied for these traits. However, a greater sample size is required to decrease the bias of GEBVs by GS and increase the power of detecting significant quantitative trait loci (QTLs) by GWAS.

Effects of supplementing rumen-protected arginine on performance of transition cows

An experiment was conducted to determine the effects of supplementing rumen-protected arginine (RPA) on productive performance in dairy cows. One-hundred and 2 cows were blocked by parity and then by energy-corrected milk (ECM) yield. Within block, cows were randomly assigned to control (CON) that received 200 g/d of a mixture of hydrogenated soybean oil and heat-treated soybean meal to supply 30 g of metabolizable protein (MP), or 200 g/d of a product containing 30 g of metabolizable arginine (RPA), which increased the dietary arginine from 5.7 to 7.5% of the MP from 250 d of gestation to 21 d postpartum. After 21 d postpartum, cows were fed the same diet and data were collected until 84 d postpartum. Cows fed RPA produced an additional 2.5 kg of colostrum (5.3 vs. 7.8 ± 1.0 kg) and 220 g more immunoglobulin G (526 vs. 746 ± 93 g) than CON cows. Supplementing RPA increased the yields of milk (32.8 vs. 34.9 ± 1.0 kg/d), ECM (37.8 vs. 40.9 ± 1.2 kg/d), and milk total solids (4.48 vs. 4.86 ± 0.14 kg/d) in the first 21 DIM. The benefits of RPA extended beyond the period of supplementation, with a 6.4% increase in yield of ECM per kg of dry matter consumed in all cows (1.88 vs. 2.00 ± 0.05 kg/kg) and an increase in ECM yield, but only in parous cows (44.2 vs. 48.5 ± 1.5 kg/d). Feeding RPA increased the concentrations of urea N in plasma pre- (12.5 vs. 13.9 ± 0.4 mg/dL) and postpartum (11.6 vs. 13.2 ± 0.4 mg/dL), and in milk during the first 21 d postpartum (11.0 vs. 12.0 ± 0.3 mg/dL). Treatment did not affect the concentrations of AA in plasma prepartum, but feeding RPA tended to increase citrulline (72.5 vs. 77.5 ± 2.7 μM), whereas RPA either tended to decrease isoleucine (129.5 vs. 120.9 ± 5.7 μM) or decreased the concentrations of leucine (181.3 vs. 170.2 ± 6.4 μM) and valine (293.2 vs. 276.7 ± 10.4 μM) postpartum. Feeding RPA increased the relative expression of transcripts involved in AA transport (SLC38A4), urea cycle (ARG1), and gluconeogenesis (PC, PEPCK, and G6PC) in hepatic tissue. Feeding diets to supply additional arginine as RPA during the transition period benefited productive performance in dairy cows that extended beyond the period of supplementation despite minor changes in plasma AA concentrations.

Effect of dietary fat source and concentration on feed intake, enteric methane and milk production in dairy cows

Dietary fat can be used in dairy cow nutrition to reduce enteric methane (CH4), but studies with multiple dietary fat concentrations are scarce. Among fat sources, rapeseed is easily accessible in Europe and North America, and palm kernel fat has been shown to be a potent inhibitor of ruminal methanogenesis. Forty-eight cows (half primiparous and half multiparous) were used in a 6 × 6 Latin square design, with 6 periods of 21 d each. Six treatments were used: a control, 3 fat concentrations (low, medium and high) of rapeseed (RS), and 2 fat concentrations (low and medium) of palm kernel fatty acids (PK). The total crude fat concentrations ranged from 3 to 7% of DM. The cows were fed the treatments as partial mixed ration, and they received additional concentrate from GreenFeed units (1 unit for 12 cows) used to measure CH4 production. Increased dietary crude fat concentration of both RS and PK reduced DMI. The reduction in DMI was stronger in cows fed medium concentration of PK than for any RS concentration, which was comparable to previous studies for both RS and PK. Digestibility of OM was highest at low fat concentration of both fat sources, and lowest at high RS concentration. Digestibility of NDF was reduced by 2 percentage units when cows were fed medium PK concentration instead of the control treatment. Rapeseed supplementation with dietary crude fat up to 5.7% of DM increased milk and energy corrected milk (ECM) yields, but the equivalent PK concentration reduced ECM. Increased fat supplementation decreased CH4 yield (g CH4/kg of DMI) linearly when RS was used, and quadratically when PK was used. Medium PK concentration reduced CH4 yield more than medium RS concentration, but there was no difference for CH4 intensity (g CH4/kg of ECM). Rapeseed fat supplementation with dietary crude fat above 5.7% of DM could reduce further CH4 yield, but fat supplementation was not accompanied by an increase in productivity. The fat source has to be accounted for when considering enteric methane reduction, as the PK provided stronger effect than RS, but the associated reduction in milk production did not support the use of PK for methane reduction.

Effect of prolactin concentration during the dry period on the subsequent milk production of dairy cows

Shortening the dry period has a negative impact on milk production of the following lactation. One possible explanation is that a period of low prolactin (PRL) concentration is necessary to restore mammary gland milk production capacity. Therefore, the objective of this study was to determine the effect of lowering blood PRL level on subsequent lactation milk production. In this experiment, quinagolide was used to inhibit PRL secretion during the dry period. Thirty Holstein cows were randomly assigned one of 3 dry period managements: a conventional (60 d) dry period (CD) and 2 short (35 d) dry period treatments (SD). Short dry period cows received either water (SDwater) or quinagolide (2 mg, SDquin) injections twice daily from dry-off until 14 d before calving. Cows were followed during the first 20 wks of the subsequent lactation. When CD cows were dry but SD cows were lactating, concentration of PRL was lower in the CD cows than in the SD cows. During the injection period, PRL of SDquin cows was lower than that of the other treatments and was greater in the blood of SDwater than in that of CD cows. After the injection period until calving, no difference in PRL concentration was observed between treatments. After calving, PRL concentration of the SDquin cows was greater than those of CD and SDwater cows. During the first 20 wks of lactation, energy corrected milk (ECM) was lower in SDwater cows than in CD and SDquin cows. The ECM of the latter groups were not different. During the same period, mammary expression of genes related to milk synthesis, pro-apoptotic genes, as well as the expression of the short and long isoforms of the PRLR genes were not affected; however, the expression of SOCS3 gene tended to be lower for the SDquin than the SDwater cows. Lowering the PRL level during short dry period restored milk production to the level normally observed after a conventional dry period, which suggests that higher PRL levels during short dry period are the cause of the lower milk production after a short dry period. Ultimately, strategies to lower blood PRL level may help the adoption of short dry period.

Impact of dairy cow personality traits and concentrate allowance on their response to training and adaptation to an automated milking system

The objectives of this study were to determine: 1) if dairy cow personality traits and concentrate allowance are associated with the behavior and performance of cows during training to use an automated milking system (AMS); and 2) if these factors were associated with the behavior and performance of cows after AMS training. Twenty-nine mid- to late-lactation Holstein cows (218 ± 49 DIM), who were milking on a rotary parlor and had never previously been milked in an AMS, were enrolled in this study. Cows were assigned to 1 of 2 dietary treatments, consisting of a basal partial mixed ration (PMR) common to both treatment groups, with a concentrate allowance (on dry matter basis) of: 1) 2.0 kg/d in the AMS (L-Tx); or 2) 6.0 kg/d in the AMS (H-Tx). Cows were trained to use the free-traffic AMS, with supervised milkings, over 72 h and were milked in this system for 63 d after training was complete. Variables relating to feeding behavior, milking activity, and production were measured from the start of AMS training until the end of the study. Between 42 and 63 d after AMS introduction, each cow was assessed for personality traits using a combined arena test consisting of exposure to a novel environment, novel object, and novel human. Principal components analysis of behaviors observed during the personality assessment revealed 2 factors (interpreted as boldness and activeness traits) that together explained 85% of the variance; each cow received a score for each trait. Associations between dietary treatment and personality traits with feeding behavior, milking activity, and production were analyzed using mixed-effect linear and logistic regression models. Cows with greater scores for the active trait produced less milk during the 3 d of AMS training compared with cows with lower scores. Within the H-Tx, more active cows had a 3.92 times greater risk of kicking off teat cups during AMS training than less active cows. However, during the 8 wk after training, more active cows had a 1.37 times lesser risk of teat cup kickoffs than those that were less active. Cows on the H-Tx produced 4.4 kg/d more energy-corrected milk compared with cows on the L-Tx in the 8 wk after training. During the 8 wk after AMS training the cows on the H-Tx consumed an average of 21.4 kg/d of PMR and were delivered 4.6 kg/d of AMS concentrate, while the L-Tx cows consumed 23.4 kg/d PMR and were delivered 2.0 kg/d of AMS concentrate. The results indicate that both dairy cow personality traits and AMS concentrate allocation influence their response to AMS training and subsequent feeding and milking behavior and production.

Mammary gland responses to altering the supply of de novo fatty acid substrates and preformed fatty acids on the yields of milk components and milk fatty acids

The objective of our study was to evaluate the effect of altering the dietary supply of acetate, palmitic acid (PA), and cottonseed on the yields of milk components and milk fatty acids (FA) in lactating dairy cows. Thirty-two multiparous Holstein cows (133 ± 57 d in milk, 50.5 ± 7.2 kg/d milk) were used in a 4 × 4 Latin square split plot design with a 2 × 2 factorial arrangement of subplot treatments. Cows were blocked by energy-corrected milk (ECM) yield and allocated to a main plot receiving a basal diet (n = 16) with no supplemental PA (Low PA) or a basal diet (n = 16) with 1.5% inclusion of a FA supplement containing ~85% PA (High PA). In each main plot, the following subplots of treatment diets were fed in a Latin square arrangement consisting of 14-d periods: 1) a control diet (CON), 2) the control diet supplemented with 3% sodium acetate (AC), 3) the control diet supplemented with 12% whole cottonseed (CS), and 4) the control diet supplemented with 3% sodium acetate and 12% whole cottonseed (CS+AC). The PA supplement and sodium acetate replaced soyhulls, and whole cottonseed replaced cottonseed hulls and meal. All diets were balanced for 30% neutral detergent fiber (NDF), 23% forage NDF, 28% starch, and 17% crude protein (CP). Sources of FA were classified as de novo (<16 carbons), mixed (16-carbon), and preformed (>16 carbons). The statistical model included the random effect of cow nested within basal diet and fixed effect of period, basal diet, acetate, cottonseed, and their interactions. Three-way interactions among basal diet, acetate, and cottonseed were observed for the yields of milk fat, 3.5% fat-corrected milk (FCM), and the molar yields of de novo FA, mixed FA, and preformed FA. In the Low PA diets, AC and CS+AC increased the yields of milk fat and FCM compared with CON and CS, whereas, in the High PA diets, CS+AC increased the yields of milk fat and FCM compared with the other treatments and AC increased milk fat yield compared with CON and CS. Compared with Low PA, High PA increased milk fat content, mixed FA yield, and tended to increase C4:0 yield. Diets containing acetate increased DMI and the yields of milk fat, ECM, FCM, de novo FA, mixed FA, and preformed FA compared with diets without acetate. Diets containing cottonseed increased the yields of milk and preformed FA, tended to increase the yields of FCM and protein, and decreased DMI and the yields of de novo FA and mixed FA compared with diets without cottonseed. In summary, in high PA diets, the inclusion of acetate plus cottonseed increased milk fat yield compared with the other treatments. The CON diet in High PA increased milk fat yield to the same extent as AC and CS+AC in Low PA suggesting PA is important for initiating milk TG synthesis. Balancing the supply of de novo FA substrates and preformed FA is important for increasing the synthesis of milk fat triglycerides and milk fat production.

The associations of early-life health and performance with subsequent dairy cow longevity, productivity, and profitability

Selecting and raising dairy animals that are more likely to reach their potential is a strategy to increase milk production efficiency and overall profitability. However, indicators are necessary for the early identification of animals that are less likely to perform well, allowing for their early culling and ensuring that resources are allocated to those with the highest potential. The objective of this study was to analyze the association between early-life animal health and performance with longevity, production, and profitability. After data cleaning, the following early-life measures (i.e., predictors) were available for 363 female calves born between June 2014 and November 2015 in eight dairy herds from New Brunswick, Canada (average: 45 calves/farm; SD: 26.1 calves/farm; median: 42 calves/farm; range: 15–95 calves/farm): birth weight, weaning weight, weaning age, weaning average daily gain (weaning ADG), immunoglobulin G (IgG) serum concentration, the occurrence of navel infection, diarrhea, and pneumonia, and if animals received antibiotic treatment between birth and weaning. Their subsequent length of life (LL), length of productive life (LPL), lifetime cumulative energy-corrected milk (ECM), and lifetime cumulative milk value (i.e., response variables) were provided by the Canadian dairy herd improvement agency. Bayesian Additive Regression Tree models were trained for each response variable using 5-fold cross-validation. Models were evaluated using the RMSE and R2. The three most important predictors were identified using permutation, and the relationship between response variables and important predictors was assessed using accumulated local effect plots. The RMSE for LL, LPL, ECM, and milk value were 1.43 years, 1.37 years, 16 314.94 kg, and $CAD 11 525.68, respectively, whereas the R2 values were 0.30, 0.25, 0.29, and 0.29, respectively, indicating a moderate relationship between predictors and response variables. Non-linear relationships were found between the response variables and important predictors. Animals born with low or high birth weights were associated with decreased LL, LPL, ECM, and milk value. The highest LL, LPL, and milk value was observed for calves weaned between 1.9 and 2.0 months old, followed by a decline for calves weaned at older ages. The lowest LL and ECM were associated with weaning ADG of 0.786 kg/day, while 0.787 kg/day was associated with the lowest LPL. Lastly, both ECM and milk value were highest when serum IgG values were 1 659 mg/dL. These findings provide valuable insights for optimizing early culling decisions and enhancing the productivity and profitability of dairy farms.

Association of Dry Period Length with Automatic Milking System, Mastitis, and Reproductive Indicators in Cows.

The objective of this study was to evaluate the association between dry period (DP) length and various indicators of productivity, reproduction, and udder health in cows managed with an automatic milking system. We analyzed records from 3861 cows, categorizing them into three groups based on their DP duration: (1) <40 days, (2) 40-70 days, and (3) DP > 70 days. Cows with a DP of 40-70 days had an average energy-corrected milk production that was 8.2 kg greater than that of cows with a short DP and 5.0 kg greater than that of cows with a long DP (p < 0.001). Milk from the 40-70-day DP group exhibited the highest lactose concentration (4.64 ± 0.01%). Additionally, cows with the longest DP had the smallest proportion of animals with a milk fat-to-protein ratio of 1.2 to 1.4. Cows with a DP of 40-70 days also showed the lowest milk electrical conductivity across all udder quarters, whereas cows with the shortest DP had the highest conductivity. The highest conception rates were observed in the group with the shortest DP. These results suggest that a DP of 40-70 days is optimal for maximizing milk production and improving both udder health and reproductive performance under AMS. Proper management of DP duration can be an effective strategy for sustainable dairy herd management.

Effects of postbiotic products from Saccharomyces cerevisiae fermentation on lactation performance, antioxidant capacities, and blood immunity in transition dairy cows

This study aimed to evaluate the effects of dietary supplementation with different types of Saccharomyces cerevisiae fermentation products (SCFP) on lactational performance, metabolism, acute phase protein response, and antioxidant capacities in dairy cows from -21 to 56 d in milk (DIM). One hundred and 80 multiparous Holstein dairy cows were blocked by parity, expected calving date, pre-trial body condition score, and previous 305-d ME yield, and then randomly assigned to 1 of 3 dietary treatments: basal diet (CON; n = 60), basal diet supplemented with 40 g/d of SCFP1 (XPC; n = 60; XPC, Diamond V, Cedar Rapids, IA), and basal diet supplemented with 19 g/d of SCFP2 (NTK; n = 60, NutriTek®, Diamond V, Cedar Rapids, IA). Blood (n = 15, 13 and 12 in the CON, XPC and NTK groups, respectively) was sampled at -7 ± 3, + 3, + 7, + 21, and + 28 d, and milk samples (n = 19, 18 and 15 in the CON, XPC and NTK groups, respectively) was sampled during 1-8 wk from a subset of cows from -21 to 56 d relative to calving. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). All data were subjected to repeated measures ANOVA. Dietary treatment (TRT), time, and their interaction (TRT × time) were considered as fixed effects and cow as the random effect. Cows fed XPC and NTK had greater energy-corrected milk (ECM). Supplementing NTK increased milk fat content and yield, and 3.5% fat-corrected milk (FCM) yield compared with CON. Milk urea nitrogen (MUN) was lower in XPC cows than CON. SCFP supplementation decreased plasma β-hydroxybutyrate (BHB), ceruloplasmin (CER), haptoglobin (HPT), and interleukin-1β (IL-1β) concentrations, whereas increased plasma phosphorus (P) concentrations. In addition, cows fed NTK showed lower creatinine (CR) and cortisol (COR) concentrations but increased plasma calcium (Ca) and myeloperoxidase (MPO) concentrations than those in the CON cows. In addition, cows fed NTK and XPC both had reduced plasma concentrations of serum amyloid-A (SAA) at 3 DIM of lactation compared with CON fed cows. Furthermore, SCFP cows had greater concentrations of plasma glucose (GLU) and calcium (Ca) than CON cows at 7 DIM, and greater concentrations of plasma phosphorus (P) at 21 DIM. Between different SCFP type fed groups, plasma concentrations of nonesterified fatty acids (NEFA), MDA, creatinine (CR), SAA, and HPT were lower in cows fed NTK compared with cows fed XPC at 7 DIM. Overall, our results indicate the potential benefits of supplementing SCFP in transition dairy cows by modulating immunity, liver metabolic function and supporting ECM yield. The results also suggest that NutriTek at 19 g/d appears to support the performance and health of dairy cows better compared with XPC at 40 g/d, based on improved metabolic and inflammatory status during the transition period.

Dietary supplementation of rumen native microbes improves lactation performance and feed efficiency in dairy cows

Objectives were to determine the effects of 2 dietary microbial additives supplemented to diets of Holstein cows on productive performance and feed efficiency. One-hundred and 17 Holstein cows were enrolled at 61 d (31 to 87 d) postpartum in a randomized complete block design experiment. Cows were blocked by parity group, as nulliparous or multiparous cows and, within parity, by pre-treatment energy-corrected milk yield. Within block, cows were randomly assigned to one of 3 treatments administered as top-dress for 140 d. Treatments consisted of either 100 g of corn meal containing no microbial additive (CON; 15 primiparous and 25 multiparous), 100 g of corn meal containing 5 g of a mixture of Clostridium beijerinckii and Pichia kudriavzevii (G1; 4 × 107 cfu of C. beijerinckii and 1 × 109 cfu of P. kudriavzevii; 14 primiparous and 24 multiparous), or 100 g of corn meal containing 5 g of a mixture of C. beijerinckii, P. kudriavzevii, Butyrivibrio fibrisolvens, and Ruminococcus bovis (G2; 4 × 107 cfu of C. beijerinckii, 1 × 109 cfu of P. kudriavzevii, 1 × 108 cfu of B. fibrisolvens, and 1 × 108 cfu of R. bovis; 15 primiparous and 24 multiparous). Intake of DM, milk yield, and BW were measured daily, whereas milk composition was analyzed at each milking 2 d a week, and body condition was scored twice weekly. Milk samples were collected on d 60 and 62 in the experiment and analyzed for individual fatty acids. The data were analyzed with mixed-effects models with orthogonal contrast to determine the impact of microbial additive (MA; CON vs. 1/2 G1 + 1/2 G2) and type of microbial additive (TMA; G1 vs. G2). Results are described in sequence as CON, G1, and G2. Intake of DM (22.2 vs. 22.4 vs. 22.4 kg/d), BW (685 vs. 685 vs. 685 kg) and the daily BW change (0.40 vs. 0.39 vs. 0.39 kg/d) did not differ among treatments; however, feeding MA tended to increase BCS (3.28 vs. 3.33 vs. 3.36). Supplementing MA increased yields of milk (39.9 vs. 41.3 vs. 41.5 kg/d), ECM (37.9 vs. 39.3 vs. 39.9 kg/d), fat (1.31 vs. 1.37 vs. 1.40 kg/d), total solids (4.59 vs. 4.75 vs. 4.79 kg/d), and ECM per kg of DMI (1.72 vs. 1.76 vs. 1.80 kg/kg). Furthermore, cows fed MA increased yields of pre-formed fatty acids in milk fat (>16C; 435 vs. 463 vs. 488 g/d), particularly unsaturated fatty acids (367 vs. 387 vs. 410 g/d), such as linoleic (C18:2 cis-9, cis-12; 30.9 vs. 33.5 vs. 35.4 g/d) and α-linolenic acids (C18:3 cis-9, cis-12, cis-15; 2.46 vs. 2.68 vs. 2.82 g/d) on d 60 and 62 in the experiment. Collectively, supplementing G1 and G2 improved productive performance of cows with no differences between the 2 MA.

Dietary saccharin sodium supplementation improves the production performance of dairy goats without residue in milk in summer

The purpose of this study was to investigate the effects of dietary saccharin sodium supplementation on production performance, serum biochemical indicators, and rumen fermentation of dairy goats in summer. Twelve Guanzhong dairy goats with similar body weight, days in milk, and milk yield were randomly divided into two dietary treatments: (1) CON: basal diet; (2) SS: basal diet + 150 mg/kg saccharin sodium on the basis of dry matter. The experiment lasted 35 d, including 7 d for adaptation and 28 d for dietary treatments, sampling and data collection. Each dairy goat was housed individually in a clean separate pen with ad libitum access to diet and water. The goats fed SS diet had increased dry matter intake (DMI; P = 0.037), 4% fat corrected milk yield (P = 0.049), energy corrected milk yield (P = 0.037), milk protein yield (P = 0.031), and total solids yield (P = 0.036). Serum activity of aspartate aminotransferase (P = 0.047) and concentrations of 70-kDa heat shock protein (P = 0.090), malondialdehyde (P = 0.092), and total protein (P = 0.057) were lower in goats fed SS diet than those fed CON diet. Supplementation of saccharin sodium tended to increase activity of glutathione peroxidase in serum (P = 0.079). The concentrations of rumen total volatile fatty acid (P = 0.042) and butyrate (P = 0.038) were increased by saccharin sodium supplementation. Dietary supplementation of saccharin sodium increased the relative abundance of Lachnobacterium (P = 0.022), Pseudoramibacter (P = 0.022), Shuttleworthia (P = 0.025), and Syntrophococcus (P = 0.037), but reduced the relative abundance of Prevotella_1 (P = 0.037) and Lachnospiraceae_UCG_008 (P = 0.037) in rumen. Saccharin sodium was observed in feces and urine of goats fed diet supplemented with saccharin sodium, but saccharin sodium was undetectable in the milk of goats receiving SS diet. In conclusion, administration of saccharin sodium was effective in increasing fat and energy corrected milk yield by increasing DMI and improving rumen fermentation and antioxidant capacity of dairy goats in summer. In addition, saccharin sodium residue was undetectable in the milk.

Heat stress has divergent effects on the milk microbiota of Holstein and Brown Swiss cows.

Heat stress (HS) is one of the pivotal causes of economic losses in dairy industries and affects welfare and performance, but its effect on milk microbiota remains elusive. It is also unclear if and how different breeds may cope with HS in sustaining productive performance. The objectives of this study were to compare a) the performance of 2 dairy breeds, namely Holstein and Brown Swiss, subjected to HS and b) the different effects of HS on the milk microbiota of the 2 breeds in thermal comfort conditions and HS. The study was carried out on 36 dairy cows, 18 per breed. The HS was induced by switching off the cooling system during a natural heat wave for 4 d. Besides the Temperature Humidity Index (THI), the animal stress was confirmed by measuring respiratory frequency and rectal temperature twice daily at 4 a.m. and 3 p.m. The HS differently impacted the 2 breeds. Rectal temperatures were higher in Holstein cows, while no changes in rectal temperature were found in Brown Swiss. Milk yield recording and sampling were performed during the morning milking of d 1 (at 4.00 a.m.) and afternoon milking of d 4 (at 5.00 p.m.). Productive parameters were also different: milk yield, fat-corrected milk, energy-corrected milk, protein and casein content, and renneting parameters were decreased in Holstein but remained unaffected in Brown Swiss. The HS also modified the milk microbiota of the 2 breeds differently. During HS, the Brown Swiss milk microbiota was richer (α diversity) than the Holstein one. Comparing the time points before and during HS within breeds showed that Brown Swiss milk microbiota was less affected by HS than Holstein's. Under the same thermal comfort condition, milk microbiota did not discriminate between Brown Swiss and Holstein. Consistently with α and β diversity, the number of operational taxonomic units (OTUs) at the genus level that changed their abundance during HS was higher in Holstein (74 OTUs) than in Brown Swiss (only 20 OTUs). The most significant changes in abundance affected Acinetobacter, Chryseobacterium, Cutibacterium, Enterococcus, Lactococcus, Prevotella-9, Serratia, and Streptococcus. In conclusion, the present report confirms and extends previous studies by demonstrating that Brown Swiss cows regulate their body temperature better than the Holstein breed. The relative thermal tolerance to HS compared with Holstein is also confirmed by changes in milk uncultured microbiota, which were more evident in Holstein than in Brown Swiss.

Effect of carbohydrate type in silages and concentrates on feed intake, enteric methane, and milk yield from dairy cows

Dietary carbohydrate manipulation can be used to reduce enteric CH4 emission, but there is a lack of studies on the interaction of different types of carbohydrates that can affect feed intake and ruminal fermentation. Understanding this interaction is necessary to make the most out of CH4 mitigation feeding strategies using different dietary carbohydrates. The aim of this study was to test the effect on enteric CH4 emission, feed intake and milk production response when cows were fed either grass-clover (GCS) or corn silage (CS) as the sole forage source (55% of dry matter, DM), in combination with either barley (BAR) or dried beet pulp (DBP) as a concentrate (21.5% of DM). Twenty-four (half first and half second parity) cows were used in a crossover design with 2 periods of 21 d each, receiving 2 of 4 diets obtained from a 2 × 2 factorial arrangement of the experimental diet. Feed intake, CH4 emission metrics and milk production were recorded at the end of the experimental periods. The diets had NDF concentrations between 258 and 340 g/kg of DM, and starch concentrations between 340 and 7.45 g/kg of DM (CS-BAR and GCS-DBP, respectively). The effects of silage and concentrate on dry matter intake (DMI) were additive, with the highest feed intake in cows fed COR-BAR, followed by cows fed COR-DBP, GCS-BAR, and GCS-DBP (21.2, 19.9, 19.1, and 18.3 kg/d). Energy corrected milk (ECM) yield was not affected by silage source in first parity cows, but it was higher for cows fed CS than cows fed GCS in second parity. The effects of silage and concentrate on CH4 production (g/d), yield (g/kg of DMI) and intensity (g/kg of ECM) were not additive as cows fed GCS had similar responses regardless of the concentrate used, but cows fed CS had lower CH4 production, yield and intensity, when fed BAR instead of DBP. The lower CH4 production, yield and intensity in cows fed CS-BAR compared with other diets could be partially explained by the nonlinear relationship between ruminal VFA and carbohydrates (NDF and starch) concentration reported in literature, however, we observed a linear relationship between acetate:propionate ratio and CH4 yield, suggesting possible other effects. The effects of silage and concentrate on the ruminal VFA were additive in first parity cows, but not in second parity cows. The interaction between dietary CHO type and parity might indicate an effect of feed intake or the energy balance of the cow. Feeding cows silage and concentrate both rich in starch can result in the lowest enteric CH4 emission.

Effects of increasing dietary inclusion of high oleic acid soybeans on milk production of high-producing dairy cows

Recent research has highlighted the importance of dietary fatty acid profile of fatty acid supplements on production responses of high-producing dairy cows. Conventional soybeans contain ∼15% oleic acid and ∼50% linoleic acid whereas high oleic acid soybeans (HOSB) contain ∼70% oleic acid and ∼7% linoleic acid. We determined the effect of increasing dietary inclusion of roasted and ground HOSB on production responses of high-producing dairy cows. Twenty-four multiparous Holstein cows (50.7 ± 4.45 kg/d of milk; 122 ± 57 DIM) were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design with 21-d periods. Treatments were increasing doses of HOSB at 0, 8, 16, and 24% DM. The HOSB replaced conventional soybean meal and hulls to maintain similar diet nutrient composition (% DM) of 27.4 - 29.4% (NDF), 20.6% forage NDF, 27.5% starch, and 15.9 - 16.5% CP. Total fatty acid content of treatments was 1.65, 3.11, 4.52, and 5.97% DM, respectively. Pre-planned polynomial orthogonal contrasts included the linear, quadratic, and cubic effects of increasing HOSB. Increasing dietary inclusion of HOSB linearly decreased DMI and milk urea nitrogen and increased yields of milk, 3.5% fat corrected milk, energy corrected milk, and milk fat, and quadratically increased milk protein. The increased response to milk fat was due to an increase in preformed milk fatty acids. Due to the increase in milk component yields and decrease in DMI, there was an increase in feed efficiency. Increasing HOSB inclusion linearly decreased plasma BUN concentration and tended to decrease plasma insulin. Increasing HOSB had no effect on BW change or BCS change. In summary, increasing dietary inclusion of HOSB up to 24% DM increased production responses of high-producing dairy cows and did not affect body reserves.

Effect of nicotinic acid supplementation on digestion, metabolism, microbiome, and production in late-lactation Holstein cows

The purpose of this experiment was to determine if nicotinic acid (NA) effects on dairy cows and rumen microbial characteristics are forage type dependent (corn silage, CS; grass silage, GS). Four late lactation (days in milk = 225 +/- 12 d) Holstein cows were used in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. The main effects were a CS (66.10% CS) based diet or a GS (79.59%) based diet with or without 12 g/d NA. Each experimental period lasted for 28 d. Milk production and milk components, blood metabolites, apparent total-tract nutrient digestibilities, minutes rumen pH were below 5.8 as an indicator of ruminal acidosis, and body temperature changes were analyzed as indicators of heat stress. Nicotinic acid supplementation did not improve apparent total-tract nutrient digestibility. Feeding a GS-based diet improved NDF and hemicellulose digestibility. Feeding a CS-based diet increased the apparent total-tract digestibility of fat, and minutes rumen pH below 5.8 for a greater proportion of the time. The CS-based diet also improved milk yield, milk fat and protein yields, and energy-corrected milk yield; however, somatic cell count and BHB were also increased. Supplementing NA tended to decrease nonesterified fatty acids, especially when combined with GS where DMI was low. There was a trend for the total protozoa population to increase when GS and NA were fed but decreased when CS and NA were fed. Nicotinic acid tended to decrease rumen protozoal populations of Dasytricha, but increased populations of Ophryoscolex and Diplodiniinae with GS diets and decreased with CS diets. Entodiniinae were increased with CS but NA had no effect. Body temperature was increased when a CS-based diet was fed when compared with a GS-based diet. More research is needed to determine how NA can affect rumen microbial protein synthesis and what kind of diets will provide the optimum effect.

Evaluation of a novel palm-free fat supplement to reduce the carbon footprint of diets for dairy cows

Most fat supplements added to dairy diets are derived from palm acid oil or palm fatty acid distillate. There are environmental concerns about palm oil production due to deforestation and high greenhouse gas (GHG) emissions. The objective of this study was to evaluate a palm-free fat supplement, Envirolac. Envirolac contains vegetable oils, marine oils and glycerine encapsulated within a cellulosic fibre-clay mineral carrier matrix. The carrier matrix has small particle size to facilitate rapid rumen passage and minimal interference with rumen digestion. Fifty cows were divided into two balanced groups of 25 cows. Each group received Control (calcium soap of palm fatty acid distilate, 0.5 kg/d) and Envirolac (0.5 kg/d) diets in a crossover design with two feeding periods of four weeks duration, so that each cow received both diets. Envirolac has a lower total fat concentration than the calcium soap, so the feeding rate delivered less total fat. When fed on Envirolac, cows yielded more milk 40.7 v 40.1 kg/d), energy-corrected milk (ECM; 42.9 v 41.3 kg/d) and milk components (1605 v 1514 g fat, 1239 v 1199 g protein, 1871 v 1839 g lactose, per day), and produced milk with higher concentrations of fat (40.1 v 38.6 g/kg) and protein (30.7 v 30.1 g/kg), than when fed on Control. When fed on Envirolac, cows produced milk with higher concentrations of fatty acids (FA) synthesised de novo in the mammary gland (25.5 v 23.6 g/100 g total FA), lower concentration of palmitic acid (35.5 v 37.2 g/100 g total FA), and higher concentrations of some long-chain fatty acids (C20:0, C20:1, C20:3n3, C21:0, C22:0, C22:6n3 and C23:0), than when fed on Control. There was no effect of treatment on dry matter intake (DMI; mean 23.4 kg/d), so feed efficiency was higher (1.83 v 1.76 kg ECM/kg DMI) for Envirolac than Control. There was no effect of treatment on dry matter digestibility (0.73), methane production (433 g/d), methane yield (19.3 g/kg DMI) or methane intensity (10.9 g/kg ECM). Feed carbon footprint of Envirolac was calculated to be 1028 g CO2eq/kg DM, which is 0.46 of the value for a calcium soap (2830 g CO2eq/kg DM), and reduced feed carbon footprint per kg ECM milk production by 11 %. This study demonstrates that Envirolac can replace palm-based fat supplements in dairy diets to improve feed efficiency and reduce the carbon footprint of milk production.

Supplementation with Combined Additive Improved the Production of Dairy Cows and Their Offspring with Maintenance of Antioxidative Stability.

Oxidative stress damage in periparturient cows decreases both production and their health; supplementation with complex additives during the periparturient period has been used as an important strategy to enhance the antioxidant status and production of dairy cows. The periparturient cows not only risk a negative energy balance due to reduced dry matter intake but also represent a sensitive period for oxidative stress. Therefore, we have developed an immunomodulatory and nutritional regulation combined additive (INC) that hopefully can improve the immune status and production of cows during the periparturient period and their offspring health and growth by improving their antioxidant stress status. The INC comprised a diverse array of additives, including water-soluble and fat-soluble vitamins, Selenomethionine, and active dry Saccharomyces cerevisiae. Forty-five multiparous Holstein cows were randomly assigned to three treatments: CON (no INC supplementation, n = 15), INC30 (30 g/d INC supplementation, n = 15), and INC60 (60 g/d INC supplementation, n = 15) based on last lactation milk yield, body condition score, and parity. Newborn calves were administered 4 L of maternal colostrum originating from the corresponding treatment and categorized based on the treatment received by their respective dams. The INC not only served to maintain the antioxidative stress system of dairy cows during the periparturient period but also showed a tendency to improve the immune response (lower tumor necrosis factor and interleukin-6) during the perinatal period. A linear decrease in concentrations of alkaline phosphatase postpartum and β-hydroxybutyrate was observed with INC supplementation. Milk fat yield, milk protein yield, and energy-corrected milk yield were also increased linearly with increasing additive supplementation. Calves in the INC30 group exhibited greater wither height and chest girth but no significant effect on average daily gain or body weight. The diarrhea frequency was linearly decreased with the incremental level of INC. Results indicate that supplementation with INC in peripartum dairy cows could be a major strategy to improve immune response, decrease inflammation, maintain antioxidant stress status in transition dairy cows, and have merit in their calves. In conclusion, this study underlines the benefits of INC supplementation during the transition period, as it improved anti-inflammatory capacity, could positively impact antioxidative stress capacity, and eventually enhanced the production performance of dairy cows and the health and growth of calves.