Predicting subacute ruminal acidosis from milk mid-infrared estimated fatty acids and machine learning on Canadian commercial dairy herds.

Our objective was to validate the possibility of detecting SARA from milk Fourier transform mid-infrared spectroscopy estimated fatty acids (FA) and machine learning. Subacute ruminal acidosis is a common condition in modern commercial dairy herds for which the diagnostic remains challenging due to its symptoms often being subtle, nonexclusive, and not immediately apparent. This observational study aimed at evaluating the possibility of predicting SARA by developing machine learning models to be applied to farm data and to provide an estimated portrait of SARA prevalence in commercial dairy herds. A first data set composed of 488 milk samples of 67 cows (initial DIM = 8.5 ± 6.18; mean ± SD) from 7 commercial dairy farms and their corresponding SARA classification (SARA+ if rumen pH <6.0 for 300 min, else SARA-) was used for the development of machine learning models. Three sets of predictive variables: i) milk major components (MMC), ii) milk FA (MFA), and iii) MMC combined with MFA (MMCFA) were submitted to 3 different algorithms, namely Elastic net (EN), Extreme gradient boosting (XGB), and Partial least squares (PLS), and evaluated using 3 different scenarios of cross-validation. Accuracy, sensitivity, and specificity of the resulting 27 models were analyzed using a linear mixed model. Model performance was not significantly affected by the choice of algorithm. Model performance was improved by including fatty acids estimations (MFA and MMCFA as opposed to MMC alone). Based on these results, one model was selected (algorithm: EN; predictive variables: MMCFA; 60.4, 65.4, and 55.3% of accuracy, sensitivity, and specificity, respectively) and applied to a large data set comprising the first test-day record (milk major components and FA within the first 70 DIM of 211,972 Holstein cows (219,503 samples) collected from 3001 commercial dairy herds. Based on this analysis, the within-herd SARA prevalence of commercial farms was estimated at 6.6 ± 5.29% ranging from 0 to 38.3%. A subsequent linear mixed model was built to investigate the herd-level factors associated to higher within-herd SARA prevalence. Milking system, proportion of primiparous cows, herd size and seasons were all herd-level factors affecting SARA prevalence. Furthermore, milk production was positively, and milk fat yield negatively associated with SARA prevalence. Due to their moderate levels of accuracy, the SARA prediction models developed in our study, using data from continuous pH measurements on commercial farms, are not suitable for diagnostic purpose. However, these models can provide valuable information at the herd level.

Decreased lactose percentage in milk associated with quarter health disorder and hyperketolactia, a proxy for negative energy balance, in dairy cows.

Several studies have described variations in lactose content (LC) in dairy cows during udder quarter health disorder or negative energy balance (NEB). However, their joint effects on LC have never been described. This was the aim of a longitudinal observational study performed on 5 Quebec dairy farms using automatic milking systems. Quarter milk samples were collected every 14 d from 5 to 300 DIM. Quarter health status was described by combining SCC level (SCC- or SCC+: < or ≥100,000 cells/mL, respectively) and infectious status (Patho- or Patho+: absence or presence of pathogens on a milk culture, respectively). Cows with NEB in early lactation (DIM <70) were identified using milk BHB content: <0.15 mM = BHB-; 0.15 to 0.19 mM = BHB+; >0.19 mM = BHB++. A total of 14,505 quarter cisternal milk samples were collected from 380 lactating cows. The quarter LC was analyzed using a mixed linear regression model with the following fixed effects: quarter health status, parity, time interval between last milking and sampling, quarter milk yield (in kg/d), DIM, and herd. A random quarter intercept with a repeated measures correlation structure and a cow random intercept were also specified. The LC of SCC+ quarters was lower (-0.17 ± 0.013 percentage points) compared with LC of SCC- quarters for both primiparous and multiparous cows. Of the 162 bacterial species identified, only 8 species had a prevalence greater than 4.0%, and just 5 of them were associated with a reduction in LC: Staphylococcus aureus, Staphylococcus chromogenes, Streptococcus dysgalactiae, Staphylococcus epidermidis, and Staphylococcus simulans. Cows identified as BHB+ and BHB++ in early lactation had a lower LC (-0.05 ± 0.019 and -0.13 ± 0.020 percentage points, respectively) compared with BHB- cows. For BHB++ cows, in both parity groups the decrease in LC (-0.20 ± 0.025 percentage points) was higher in SCC+ quarters compared with SCC- quarters. Moreover, the additive effect of the quarter health status and NEB on milk LC was greater with larger increases in BHB. Our findings highlight the necessity to jointly take into consideration both quarter health status and milk BHB concentration when using LC as a biomarker for NEB.

Predicted essential fatty acid intakes for a group of dairy cows also apply at individual animal level.

The ruminant requirements for essential fatty acids (EFAs), particularly linoleic acid (LA) and alpha-linolenic acid (ALA), have not been fully determined, although evidence suggests that an adequate supply of polyunsaturated fatty acids (FAs) could improve immunity and reproduction in transition cows. In previous studies, we predicted EFA intake for a group of cows based on animal characteristics and milk EFA secretions. However, to support precision livestock feeding, we need to match the nutrient requirements and intakes of each cow as closely as possible. Our group-level predictions may not be accurate enough to estimate the EFA intake of an individual cow, due to inter-individual variations in EFA digestion and metabolism related to differences in feed intake, intake patterns, and the composition and functioning of the rumen microbiota. To address this issue, here we set out to establish specific equations that predict EFA intake for an individual cow based on the difference (i.e. the residuals) between observed EFA intake and the predicted EFA intake based on our group-level equations. We studied a database of individual dairy cows (26 experiments; 503 datapoints from three research teams) and we predicted the residuals from (1) dietary and animal-related factors (i.e. full predictions) and (2) animal-related factors only (i.e. field predictions), which are considered more field-amenable. The variance of predicted LA and log ALA intake was explained to 68% by observed LA intake and 66% by observed log ALA intake, respectively. The residuals of LA intake were predicted by dietary ALA content, total FA intake, BW, milk yield and fat content in full predictions, and by BW, feeding level, milk yield and fat content, and sum of milk C4:0 to C14:0 FA in field predictions. The log residuals of ALA intake were predicted by dietary NDF and total FA contents, NDF intake, BW, milk protein, LA and ALA contents, and fat yield in full predictions, and by BW, DM intake, milk LA and ALA contents, and fat yield in field predictions. The field predictions showed a moderate loss of accuracy compared to full predictions based on RMSE of prediction (from 38 to 54 g/d for LA and from 0.090 to 0.12 log (g/d) for ALA). This work is the first to predict the EFA intake of an individual cow based on previously established group-level predictions of EFA intake adjusted for dietary and animal-related factors.

Comparing dehulled hemp meal and canola meal as a protein supplement for lactating dairy cows.

Effects of replacing canola meal with dehulled hemp meal in the diet of lactating dairy cows on the dry matter intake (DMI), milk production, milk fatty acid profile, blood metabolites, total-tract nutrient digestibility, and transfer of cannabinoids were determined in 12 lactating, nonpregnant Holstein cows. These cows were used in a 3 × 3 Latin square design with three 3-wk experimental periods consisting of 2 wk of adaptation and 1 wk of sampling. Cows received basal partial mixed rations supplemented with either 15% dry matter (DM) canola meal (CM15), 15% DM dehulled hemp meal (HM15), or 7.5% DM dehulled hemp meal and 7.5% DM canola meal (CM7.5HM7.5). Diets were formulated to be isoenergetic and isonitrogenous, but the HM15 and CM7.5HM7.5 diets contained, on average 1.2 percentage units more crude protein (CP) that the CM15 diet. The CP of the dehulled hemp meal contained less soluble protein than that of canola meal. Hence, the intake of soluble protein did not differ among diets. Canola meal contained less crude fat than hemp seed meal (3.46% vs. 8.25% DM). The lipid fraction of canola meal fat contained more oleic acid (C18:1 cis-9; 47.3 vs. 14.9 g/100 g of fatty acids, FA) and vaccenic acid (18:1 cis-11; 13.7 vs. 1.2 g/100 g of FA) and less linoleic acid (C18:2n-6; 21.9 vs. 55.7 g/100 g of FA) and α linolenic acid (C18:3n-3; 3.2 vs. 8.9 g/100 g of FA) than the lipid fraction of hemp seed meal. The hemp seed meal contained 4.9 µg/g cannabidiol, 5.1 µg/g cannabidiolic acid, and 0.1 µg/g tertahydroxycannabinolic acid A. Treatments did not differ in DMI, yields of milk, milk protein and milk fat, total-tract neutral detergent fiber digestibility, and blood plasma concentrations of ß-hydroxybutyrate and nonesterified FA. Apparent total-tract DM digestibility was lowest in the HM15 treatment, whereas the CP digestibility and the concentrations of urea in blood, urine, and milk were lowest in the CM15 treatment. Cannabinoids were not detected in urine, milk, and blood plasma. Replacing canola meal with hemp seed meal increased milk fat contents of polyunsaturated fatty acids (PUFA), which were 3.42, 3.90, and 4.25 g/100 g of FA for the CM15, CM7.5HM7.5, and HM15 treatments, respectively. Especially, the milk fat contents of 18:2n-6 (1.99 vs. 1.56 g/100 g FA) and 18:3n-3 (0.31 vs. 0.43 g/100 g FA) were increased by hemp meal feeding. Especially, the milk fat contents of 18:2n-6 (1.99 vs. 1.56 g/100 g FA) and 18:3n-3 (0.31 vs. 0.43 g/100 g FA) were increased by hemp meal feeding. Our data show that hemp seed meal is a suitable and safe replacement for canola meal as a feed for lactating dairy cows and that this replacement increases CP digestibility and urea in urine, milk, and blood plasma, as well the PUFA content of milk fat.

Efficacy and safety of nivolumab for patients with pre-treated type B3 thymoma and thymic carcinoma: results from the EORTC-ETOP NIVOTHYM phase II trial.

BACKGROUND: Thymic malignancies are rare intrathoracic tumors, which may be aggressive and difficult to treat. They represent a therapeutic challenge in the advanced/metastatic setting, with limited treatment options after the failure of first-line platinum-based chemotherapy. They are frequently associated with autoimmune disorders that also impact oncological management. MATERIALS AND METHODS: NIVOTHYM is an international, multicenter, phase II, two-cohort, single-arm trial evaluating the activity and safety of nivolumab [240 mg intravenously (i.v.) q2 weeks] alone or with ipilimumab (1 mg /kg i.v. q6 weeks) in patients with advanced/relapsed type B3 thymoma or thymic carcinoma, after exposure to platinum-based chemotherapy. The primary endpoint is progression-free survival rate at 6 months (PFSR-6) based on RECIST 1.1 as per independent radiological review. RESULTS: From April 2018 to February 2020, 55 patients were enrolled in 15 centers from 5 countries. Ten patients (18%) had type B3 thymoma and 43 (78%) had thymic carcinoma. The majority were male (64%), and the median age was 58 years. Among the 49 eligible patients who started treatment, PFSR-6 by central review was 35% [95% confidence interval (CI) 22% to 50%]. The overall response rate and disease control rate were 12% (95% CI 5% to 25%) and 63% (95% CI 48% to 77%), respectively. Using the Kaplan-Meier method, median progression-free survival and overall survival by local assessment were 6.0 (95% CI 3.1-10.4) months and 21.3 (95% CI 11.6-not estimable) months, respectively. In the safety population of 54 patients, adverse events (AEs) of grade 1/2 were observed in 22 (41%) patients and grade 3/4 in 31 (57%) patients. Treatment-related AEs of grade 4 included one case of neutropenia, one case of immune-mediated transaminitis, and two cases of myocarditis. CONCLUSIONS: Nivolumab monotherapy demonstrated an acceptable safety profile and objective activity, although it has been insufficient to meet its primary objective. The second cohort of NIVOTHYM is currently ongoing to assess the combination of nivolumab plus ipilimumab.

Increased dietary vitamin D3 and calcium partially alleviate heat stress symptoms and inflammation in lactating Holstein cows independent of dietary concentrations of vitamin E and selenium.

Twelve multiparous Holstein cows (42.2 ± 5.6 kg of milk/d; 83 ± 27 d in milk) were used in a split-plot design testing the effects of mineral and vitamin supplementation on the time course of animal performance, metabolism, and inflammation markers during heat stress. The main plot was the average concentrations of dietary vitamin E and Se (adequate: 11.1 IU/kg of vitamin E and 0.55 mg/kg of Se, and high: 223 IU/kg of vitamin E and 1.8 mg/kg of Se, respectively). Within each plot, cows were randomly assigned to (1) heat stress (HS) with adequate concentrations of vitamin D3 and Ca (1,012 IU/kg and 0.73%, respectively), (2) HS with high concentrations of vitamin D3 and Ca (HS+D3/Ca; 3,764 IU/kg and 0.97%, respectively), or (3) pair-feeding (PF) in thermoneutrality with adequate concentrations of vitamin D3 and Ca (1,012 IU/kg and 0.73% Ca) in a Latin square design with 14-d periods and 7-d washouts. The highest rectal temperature was recorded at 1700 h for HS (39.4°C; mean of d 1 to 14), being 1.2 and 0.8°C greater than for PF and HS+D3/Ca, respectively. Respiratory rate and water intake were higher in HS (73 breaths/min and 115 L/d, respectively) relative to PF (28 breaths/min and 76 L/d). Heat stress decreased dry matter intake progressively, reaching a nadir on d 5 to 7 (33% reduction) and was not different between treatments. Milk yield decreased progressively in all treatments, but remained greater in PF relative to HS from d 3 to 14 (10%), whereas HS and HS+D3/Ca were not different. Milk fat, protein, and lactose concentrations and yields were lower in HS relative to PF from d 3 to 14, but not different between HS and HS+D3/Ca. Relative to PF, preprandial insulin concentrations were increased in HS, whereas plasma nonesterified fatty acids were decreased on d 7 and 14. Plasma lipopolysaccharide-binding protein concentrations increased in HS cows on d 7 and 14, respectively, relative to PF, whereas they were reduced in HS + D3/Ca on d 14. Plasma C-reactive protein, tumor necrosis factor-α, and fecal calprotectin were increased in HS relative to both PF and HS+D3/Ca on d 7 and 14. Rectal temperature was positively associated with plasma lipopolysaccharide-binding protein (r = 0.72), tumor necrosis factor-α (r = 0.74), C-reactive protein (r = 0.87), and with milk somatic cells (r = 0.75). Plasma 8-hydroxy-2-deoxyguanosine concentrations presented a 3-way interaction, where 8-hydroxy-2-deoxyguanosine was lower in HS than in PF on d 7 and 14, and lower in HS+D3/Ca relative to HS on d 14 in the adequate vitamin E and Se treatment, but no effects were observed in the high vitamin E and Se group. Plasma superoxide dismutase concentrations increased over time, and were higher in HS relative to PF on d 14, whereas HS+D3/Ca was similar to HS. Heat stress markedly reduced milk production and milk components while increasing markers of leaky gut and inflammation. In contrast, vitamin D3 and Ca supplementation reduced hyperthermia (d 7-14), markers of leaky gut, and inflammation independent of dietary concentrations of vitamin E and Se.

Relationship between farm management strategies, reticuloruminal pH variations, and risks of subacute ruminal acidosis.

Low reticuloruminal pH (rpH), often observed in subacute ruminal acidosis (SARA), may negatively affect rumen health and animal performance. To investigate the variability of rpH and the prevalence of SARA on commercial farms, we conducted an observational study on 110 early-lactation Holstein cows of different parities from 12 farms selected to cover a broad range of farm management strategies. The rpH of each cow was continuously monitored for 50 d using wireless boluses. To study the effects of animal and farm management characteristics on rpH, we used a multivariable mixed model analysis with the animal and farm as random effects. Automatic milking system and presence of corn silage in the ration were associated with a decrease in rpH of 0.37 and 0.20 pH units, respectively, whereas monensin supplementation was associated with an increase of 0.27 pH units. The rpH increased by 0.15 pH units during the first 60 d in milk. We defined a SARA-positive day as rpH below 5.8 (SARA5.8) or 6.0 (SARA6.0) for at least 300 min for 1 d. Using those definitions, during our study, a total of 38 (35%) and 65 (59%) cows experienced at least one episode of SARA5.8 and SARA6.0, respectively. The proportion of cows with at least one SARA-positive day varied among farms from 0 to 100%. Automatic milking system was associated with an increased risk of SARA5.8 (odds ratio: 10) and SARA6.0 (odds ratio: 11). The use of corn silage was associated with an increased risk of SARA5.8 (odds ratio: 21), whereas the use of monensin was associated with a decreased risk of SARA5.8 (odds ratio: 0.02). Our study shows that rpH is quite variable among farms, but also among animals on the same farm. We also show that multiple animal and farm characteristics are associated with rpH variability and the risk of SARA under commercial conditions.

Effects of direct-fed Bacillus subtilis and Bacillus licheniformis on production performance and milk fatty acid profile in dairy cows.

The aim of the study was to determine the effect of a Bacillus-based direct-fed microbial on performance of mid-lactating Holstein dairy cows and on their milk fatty acid composition. Six multiparous cows fitted with a rumen cannula were used in a randomized replicated crossover design. Cows received 200 g/d of either whey powder as a control or BioPlus 2B (Chr. Hansen), a commercial direct-fed microbial providing Bacillus subtilis and Bacillus licheniformis, representing a daily dose of 6.4 × 1011 cfu, and using whey powder as a carrier. The 2 experimental periods lasted 14 d and were separated by a 7-d washout interval. Samples were collected on d 0, 13, and 14 of each period. Data from d 0 were used as covariate. Significance was declared at P ≤ 0.05 and tendency at 0.05

Combined biotin, folic acid, and vitamin B12 supplementation given during the transition period to dairy cows: Part II. Effects on energy balance and fatty acid composition of colostrum and milk.

Biotin (B8), folate (B9), and vitamin B12 (B12) are involved in several metabolic reactions related to energy metabolism. We hypothesized that a low supply of one of these vitamins during the transition period would impair metabolic status. This study was undertaken to assess the interaction between B8 supplement and a supplementation of B9 and B12 regarding body weight (BW) change, dry matter intake, energy balance, and fatty acid (FA) compositions of colostrum and milk fat from d -21 to 21 relative to calving. Thirty-two multiparous Holstein cows housed in tie stalls were randomly assigned, according to their previous 305-d milk yield, to 8 incomplete blocks in 4 treatments: (1) a 2-mL weekly i.m. injection of saline (0.9% NaCl; B8-/B9B12-); (2) 20 mg/d of dietary B8 (unprotected from ruminal degradation) and 2-mL weekly i.m. injection of 0.9% NaCl (B8+/B9B12-); (3) 2.6 g/d of dietary B9 (unprotected) and 2-mL weekly i.m. injection of 10 mg of B12 (B8-/B9B12+); (4) 20 mg/d of dietary B8, 2.6 g/d of dietary B9, and 2-mL weekly i.m. injection of 10 mg of B12 (B8+/B9B12+) in a 2 × 2 factorial arrangement. Colostrum was sampled at first milking. and milk samples were collected weekly on 2 consecutive milkings and analyzed for FA composition. Body condition score and BW were recorded every week throughout the trial. Within the first 21 d of lactation, B8-/B9B12+ cows had an increased milk yield by 13.5% [45.5 (standard error, SE: 1.8) kg/d] compared with B8-/B9B12- cows [40.1 (SE: 1.9)], whereas B8 supplement had no effect. Even though body condition score was not affected by treatment, B8-/B9B12+ cows had greater BW loss by 24 kg, suggesting higher mobilization of body reserves. Accordingly, milk de novo FA decreased and preformed FA concentration increased in B8-/B9B12+ cows compared with B8-/B9B12- cows. In addition, cows in the B8+/B9B12- group had decreased milk de novo FA and increased preformed FA concentration compared with B8-/B9B12- cows. Treatment had no effect on colostrum preformed FA concentration. Supplemental B8 decreased concentrations of ruminal biohydrogenation intermediates and odd- and branched-chain FA in colostrum and milk fat. Moreover, postpartum dry matter intake for B8+ cows tended to be lower by 1.6 kg/d. These results could indicate ruminal perturbation caused by the B8 supplement, which was not protected from rumen degradation. Under the conditions of the current study, in contrast to B8+/B9B12- cows, B8-/B9B12+ cows produced more milk without increasing dry matter intake, although these cows had greater body fat mobilization in early lactation as suggested by the FA profile and BW loss.

Consolidation nivolumab and ipilimumab versus observation in limited-disease small-cell lung cancer after chemo-radiotherapy - results from the randomised phase II ETOP/IFCT 4-12 STIMULI trial.

BACKGROUND: Concurrent chemotherapy and thoracic radiotherapy followed by prophylactic cranial irradiation (PCI) is the standard treatment in limited-disease small-cell lung cancer (LD-SCLC), with 5-year overall survival (OS) of only 25% to 33%. PATIENTS AND METHODS: STIMULI is a 1:1 randomised phase II trial aiming to demonstrate superiority of consolidation combination immunotherapy versus observation after chemo-radiotherapy plus PCI (protocol amendment-1). Consolidation immunotherapy consisted of four cycles of nivolumab [1 mg/kg, every three weeks (Q3W)] plus ipilimumab (3 mg/kg, Q3W), followed by nivolumab monotherapy (240 mg, Q2W) for up to 12 months. Patient recruitment closed prematurely due to slow accrual and the statistical analyses plan was updated to address progression-free survival (PFS) as the only primary endpoint. RESULTS: Of the 222 patients enrolled, 153 were randomised (78: experimental; 75: observation). Among the randomised patients, median age was 62 years, 60% males, 34%/65% current/former smokers, 31%/66% performance status (PS) 0/1. Up to 25 May 2020 (median follow-up 22.4 months), 40 PFS events were observed in the experimental arm, with median PFS 10.7 months [95% confidence interval (CI) 7.0-not estimable (NE)] versus 42 events and median 14.5 months (8.2-NE) in the observation, hazard ratio (HR) = 1.02 (0.66-1.58), two-sided P = 0.93. With updated follow-up (03 June 2021; median: 35 months), median OS was not reached in the experimental arm, while it was 32.1 months (26.1-NE) in observation, with HR = 0.95 (0.59-1.52), P = 0.82. In the experimental arm, median time-to-treatment-discontinuation was only 1.7 months. CTCAE v4 grade ≥3 adverse events were experienced by 62% of patients in the experimental and 25% in the observation arm, with 4 and 1 fatal, respectively. CONCLUSIONS: The STIMULI trial did not meet its primary endpoint of improving PFS with nivolumab-ipilimumab consolidation after chemo-radiotherapy in LD-SCLC. A short period on active treatment related to toxicity and treatment discontinuation likely affected the efficacy results.

Milk production and efficiency of utilization of nitrogen, metabolizable protein, and amino acids are affected by protein and energy supplies in dairy cows fed alfalfa-based diets.

Alfalfa has a lower fiber digestibility and a greater concentration of degradable protein than grasses. Dairy cows could benefit from an increased digestibility of alfalfa fibers, or from a better match between nitrogen and energy supplies in the rumen. Alfalfa cultivars with improved fiber digestibility represent an opportunity to increase milk production, but no independent studies have tested these cultivars under the agroclimatic conditions of Canada. Moreover, decreasing metabolizable protein (MP) supply could increase N use efficiency while decreasing environmental impact, but it is often associated with a decrease in milk protein yield, possibly caused by a reduced supply of essential AA. This study evaluated the performance of dairy cows fed diets based on a regular or a reduced-lignin alfalfa cultivar and measured the effect of energy levels at low MP supply when digestible His (dHis), Lys (dLys), and Met (dMet) requirements were met. Eight Holstein cows were used in a double 4 × 4 Latin square design, each square representing an alfalfa cultivar. Within each square, 4 diets were tested: the control diet was formulated for an adequate supply of MP and energy (AMP_AE), whereas the 3 other diets were formulated to be deficient in MP (DMP; formulated to meet 90% of the MP requirement) with deficient (94% of requirement: DMP_DE), adequate (99% of requirement: DMP_AE), or excess energy supply (104% of requirement; DMP_EE). Alfalfa cultivars had no significant effect on all measured parameters. As compared with cows receiving AMP_AE, the dry matter intake of cows fed DMP_AE and DMP_EE was not significantly different but decreased for cows fed DMP_DE. The AMP_AE diet provided 103% of MP and 108% of NEL requirements whereas DMP_DE, DMP_AE, and DMP_EE diets provided 84, 87, and 87% of MP and 94, 101, and 107% of NEL requirements, respectively. In contrast to design, feeding DMP_EE resulted in a similar energy supply compared with AMP_AE, although MP supply has been effectively reduced. This resulted in a maintained milk and milk component yields and improved the efficiency of utilization of N, MP, and essential AA. The DMP diets decreased total N excretion, whereas DMP_AE and DMP_EE diets also decreased milk urea-N concentration. Reducing MP supply without negative effects on dairy cow performance is possible when energy, dHis, dLys, and dMet requirements are met. This could reduce N excretion and decrease the environmental impact of milk production.

Potassium carbonate as a supplement to improve milk fat concentration and yield in early-lactating dairy goats fed a high-starch, low-fiber diet.

This study investigated the use of K2CO3 as dietary buffer to prevent or to recover from low milk fat production when early-lactating dairy goats are fed a high-starch, low-fiber (HSLF) diet. At kidding, 30 Alpine goats housed in pens with Calan gate feeders received a total mixed ration with a forage-to-concentrate ratio of 55:45 on a dry matter (DM) basis for a baseline period of 27 ± 4 d. Goats (milk yield, 4.14 ± 0.88 kg/d; milk fat, 4.28 ± 0.52%; mean ± SD) were then assigned to 1 of 10 blocks according to parity (first vs. second or more) and milk fat concentration, and fed a HSLF diet containing 45% forages and 55% concentrates for 2 experimental periods of 28 d. Treatments were identified as (1) control, in which the HSLF diet was fed throughout both periods; (2) preventive, in which the HSLF diet supplemented with K2CO3 (1.6% of DM) was fed during both periods; and (3) recovery, in which the HSLF diet was fed during the first period (P1) and the HSLF diet supplemented with K2CO3 was fed during the second period (P2). Data from P1 and P2 were analyzed separately. In P1, preplanned contrasts were used to evaluate the preventive effect of K2CO3 (control and recovery, both groups receiving the same diet during this period, vs. preventive), and in P2, to assess the potential of K2CO3 to alleviate an already existing state of low milk fat (control vs. recovery and preventive vs. recovery). Feeding the HSLF diet in P1 moderately decreased milk fat concentration (-16%) and yield (-13%) as compared with baseline. Dietary addition of K2CO3 decreased DM intake by 12 and 14% in P1 and P2, respectively. Ruminal pH was not different among treatments. There was also no significant difference in milk yield (4.13 and 3.71 kg/d on average in P1 and P2, respectively) for any tested contrasts. In P1, milk fat concentration and yield did not differ among goats fed control (3.58% and 151 g/d, respectively) and preventive (3.67% and 148 g/d, respectively) diets. In P2, milk fat concentration and yield did not differ among goats fed the control diet (3.38% and 137 g/d, respectively), and diets where K2CO3 was used as preventive (3.44% and 126 g/d, respectively) or recovery treatment (3.25% and 113 g/d, respectively). Supplementing a high-concentrate diet with 1.6% K2CO3 was therefore not effective in either preventing or suppressing already existing conditions of low milk fat production in dairy goats.

Effects of abomasal infusions of fatty acids and 1-carbon donors on apparent fatty acid digestibility and incorporation into milk fat in cows.

Our primary objective was to determine the effects of the abomasal infusion of 16-carbon (16C) and 22-carbon (22C) fatty acids (FA) on apparent FA digestibility, plasma FA concentrations, and their incorporation into milk fat in cows. Our secondary objective was to study the effects of 1-carbon donors choline and l-serine on these variables. Five rumen-cannulated Holstein cows (214 ± 4.9 d in milk; 3.2 ± 1.1 parity) were enrolled in a 5 × 5 Latin square experiment with experimental periods lasting 6 d. Abomasal infusates consisted of (1) palmitic acid (PA; 98% 16:0 of total fat), (2) PA + choline chloride (PA+CC; 50 g/d of choline chloride), (3) PA + l-serine (PA+S; 170 g/d of l-serine), (4) behenic acid (BA; 92% 22:0 of total fat), and (5) docosahexaenoic acid algal oil (DHA; 47.5% DHA of total fat). Emulsions were formulated to provide 301 g/d of total FA and were balanced to provide a minimum of 40 and 19 g/d of 16:0 and glycerol, respectively, to match the content found in the infused algal oil. Apparent digestibility of FA was highest in DHA, intermediate in PA, and lowest in BA. Digestibility of 16C FA was lowest in BA and highest in PA. The digestibility of 22C FA was highest in DHA relative to BA (99 vs. 58%), whereas 1-carbon donors had no effect on 22C FA digestibility. Plasma 16C FA concentrations were greatest with PA treatment, and 22C FA concentrations were ~3-fold greater in DHA-treated cows relative to all other treatments. Milk fat 16:0 content was highest in PA relative to BA and DHA (e.g., 37 vs. 27% in PA and DHA), whereas the milk yield of 16:0 was higher in PA relative to DHA (i.e., 454 vs. 235 g/d). Similarly, milk 22:0 content and yield were ~10-fold higher in BA relative to all other treatments, whereas DHA treatment resulted in higher content and yield of 22:6 in milk fat relative to all other treatments (41- and 38-fold higher, respectively). Consequently, the content of FA >16C (i.e., preformed) was higher in milk fat from cows infused with BA and DHA relative to PA. De novo FA content in milk did not differ between PA, PA+CC, and PA+S (~16% of milk fat) but was higher in BA and DHA treatments (19 and 21%, respectively). We conclude that FA carbon chain length and degree of saturation affected FA digestibility and availability for absorption as well as their incorporation into milk fat. The abomasal infusion of choline chloride and l-serine did not modify these variables relative to infusing palmitic acid alone.

Effects of a dietary supplement enriched in palmitoleic acid on fatty acid composition of follicular fluid, granulosa cell metabolism, and oocyte developmental capacity in early lactation dairy cows.

In high-yielding dairy cows, some fertility traits can be influenced by the fatty acid (FA) composition of the follicular fluid during early lactation. The first objective of the current study was to evaluate the potential of dietary supplements enriched in specific FA to influence the FA composition of follicular fluid lipid classes in early lactation dairy cows. The second objective was to determine the influence of the resulting follicular fluid FA composition on the folliculogenesis, lipid and energy metabolism of granulosa cells, as well as oocyte quality and embryo development. Twenty Holstein multiparous cows in late gestation were randomly assigned to 200 g/d of FA supplements enriched in (1) palmitic acid (control treatment; 82% 16:0; PA) in the rumen or (2) palmitoleic acid (sea buckthorn oil; 27% cis-9 16:1, 28% 16:0, 22% cis-9 18:1, and 11% cis-9,cis-12 18:2; SBT) in the abomasum. The treatment period ranged from 20 ± 5 d precalving to 67 ± 2 d postcalving. Cumulus-oocyte complexes, granulosa cells, and follicular fluid were recovered from 2 sequential sessions of ovum pick-up (OPU-1 and OPU-2) at 46 and 67 ± 2 d postcalving (mean ± standard deviation). On the same days, blood samples were collected. Milk performance was recorded, and feed and milk samples were collected from d 8 to 10 ± 3 (onset of lactation), d 35 to 37 ± 2 (before OPU-1), and d 63 to 65 ± 2 (before OPU-2). Treatments did not affect milk yield or fat concentration throughout the experimental trial. Compared with PA, SBT increased the cis-9 16:1 concentration in milk fat, in plasma esterified lipid classes (phospholipids, cholesterol esters, and triacylglycerols), and in follicular fluid phospholipids and cholesterol esters at OPU-1. Abundance of mRNA for stearoyl-CoA desaturase 1 and 5, and perilipin 2 in granulosa cells was not different between treatments, but an increase in the level of stearoyl-CoA desaturase 5 was observed between the 2 OPU periods. Treatments did not affect oocyte quality and developmental capacity or embryo lipid metabolism when cultivated in vitro. These results suggest that limited modifications in the FA composition of the oocyte microenvironment via dietary lipid supplements enriched in specific FA had no major effects on granulosa cell metabolism and oocyte developmental capacity in early lactation cows.

Characterization of raft microdomains in bovine mammary tissue during lactation: How they are modulated by fatty acid treatments.

The objective of the current study was first to characterize lipid raft microdomains isolated as detergent-resistant membranes (DRM) from mammary gland tissue, and second to determine how dietary fatty acids (FA) such as conjugated linoleic acid (CLA), 19:1 cyclo, and long-chain n-3 polyunsaturated FA affect lipid raft markers of mammary cells, and to finally establish relationships between these markers and lactation performance in dairy cows. Eight Holstein cows were used in a replicated 4 × 4 Latin square design with periods of 28 d. For the first 14 d, cows received daily an abomasal infusion of (1) 406 g of a saturated FA supplement (112 g of 16:0 + 230 g of 18:0) used as a control; (2) 36 g of a CLA supplement (13.9 g of trans-10,cis-12 18:2) + 370 g of saturated FA; (3) 7 g of Sterculia fetida oil (3.1 g of 19:1 cyclo, STO) + 399 g of saturated FA; or (4) 406 g of fish oil (55.2 g of cis-5,cis-8,cis-11,cis-14,cis-17 20:5 + 59.3 g of cis-4,cis-7,cis-10,cis-13,cis-16,cis-19 22:6, FO). Mammary biopsies were harvested on d 14 of each infusion period and were followed by a 14-d washout interval. Cholera toxin subunit B, which specifically binds to ganglioside M-1 (GM-1), a lipid raft marker, was used to assess its distribution in DRM. Infusions of CLA, STO, and FO were individually compared with the control, and significance was declared at P ≤ 0.05. Milk fat yield was decreased with CLA and FO, but was not affected by STO. Milk lactose yield was decreased with CLA and STO, but was not affected by FO. Mammary tissue shows a strong GM-1-signal enrichment in isolated DRM from mammary gland tissue. Caveolin (CAV) and flotillin (FLOT) are 2 proteins considered as lipid raft markers and they are present in DRM from mammary gland tissue. Distributions of GM-1, CAV-1, and FLOT-1 showed an effect of treatments determined by their subcellular distributions in sucrose gradient fractions. Regardless of treatments, data showed positive relationships between the yield of milk fat, protein, and lactose, and the abundance GM-1 in DRM fraction. Milk protein yield was positively correlated with relative proportion of FLOT-1 in the soluble fraction, whereas lactose yield was positively correlated with relative proportion of CAV-1 in the DRM fractions. Infusion of CLA decreased mRNA abundance of CAV-1, FLOT-1, and FLOT-2. Regardless of treatments, a positive relationship was observed between fat yield and mRNA abundance of FLOT-2. In conclusion, although limited to a few markers, results of the current experiment raised potential links between variation in specific biologically active component of raft microdomains in bovine mammary gland and lactation performances in dairy cows.

Effects of dietary deoiled soy lecithin supplementation on milk production and fatty acid digestibility in Holstein dairy cows.

Deoiled soy lecithin is a feed additive enriched in phospholipids. Our study evaluated the effects of dietary deoiled soy lecithin supplementation on (1) milk production and composition, (2) plasma and milk fatty acid (FA) content and yield, and (3) apparent FA digestibility and absorption in lactating dairy cows fed fractionated palm fat. In a split-plot Latin square design, 16 Holstein cows (160 ± 7 days in milk; 3.6 ± 1.2 parity) were randomly allocated to a main plot receiving a corn silage and alfalfa haylage-based diet with palm fat containing either moderate (MPA) or high palmitic acid (HPA) content at 1.75% of ration dry matter (72 or 99% palmitic acid, respectively; n = 8/palm fat diet). On each palm fat diet, deoiled soy lecithin was top-dressed at 0, 0.12, 0.24, or 0.36% of ration dry matter in a replicated 4 × 4 Latin square design. Following a 14-d covariate period, lecithin supplementation spanned 14 d, with milk and blood collected during the final 3 d. Milk composition and pooled plasma markers were measured. The statistical model included the fixed effects of palm fat type, lecithin dose, period, and the interaction between palm fat type and lecithin dose. The random effect of cow nested within palm fat group was also included. Lecithin linearly decreased dry matter intake. In cows fed HPA, lecithin feeding reduced milk fat content and tended to decrease milk fat yield. Although no changes in milk yield were observed, a quadratic reduction in 3.5% fat-corrected milk was observed with increasing lecithin dose. Lecithin linearly increased energy-corrected milk efficiency in cows fed MPA. Lecithin supplementation also decreased milk urea nitrogen, relative to unsupplemented cows. The proportion of 16-carbon FA in milk fat decreased linearly with lecithin dose, whereas 18-carbon FA increased linearly. Lecithin reduced de novo FA (<16-carbon) content and tended to increase preformed FA (>16-carbon) content in a linear manner. Compared with MPA, HPA diets reduced apparent total and 16-carbon FA digestibility and absorption. Deoiled soy lecithin feeding did not modify FA digestibility or absorption. Our observations suggest that soy lecithin feeding modifies rumen digestion to reduce dry matter intake and change milk composition.

Short communication: Effects of dietary deoiled soy lecithin supplementation on circulating choline and choline metabolites, and the plasma phospholipid profile in Holstein cows fed palm fat.

Dietary lecithin is a source of choline. Our objective was to evaluate the effects of dietary deoiled soy lecithin feeding on circulating choline, choline metabolites, and the plasma phospholipid profile in lactating dairy cows fed fractionated palm fatty acids. In a split-plot Latin square design, 16 Holstein cows (160 ± 7 d in milk; 3.6 ± 1.2 parity) were randomly allocated to a main plot receiving a corn silage and alfalfa haylage-based diet with palm fat containing either moderate or high palmitic acid content at 1.75% of ration dry matter (moderate and high palmitic acid containing 72 or 99% palmitic acid in fat supplement, respectively; n = 8/palm fat diet). Within each palm fat group, deoiled soy lecithin was top-dressed at 0, 0.12, 0.24, or 0.36% of ration dry matter in a replicated 4 × 4 Latin square design with 14-d experimental periods. A 14-d covariate period was used to acclimate cows to palm fat feeding without lecithin supplementation. Blood sampling occurred during the final 3 d of each experimental period. Plasma choline and choline metabolites were quantified using liquid chromatography and mass spectrometry. Plasma phospholipids were profiled using time-of-flight mass spectrometry. Whereas no effects of treatments were detected for plasma choline or methionine, lecithin feeding increased the plasma concentrations of choline metabolites trimethylamine N-oxide and dimethylglycine (24 and 11%, respectively). Plasma phosphatidylcholine (PC) and sphingomyelin (SM) concentrations increased with deoiled lecithin feeding (e.g., PC 16:0/22:6 and SM d18:1/18:3). Lecithin supplementation also increased plasma lysophosphatidylcholine (LPC) concentrations (e.g., LPC 18:0) while reducing plasma phosphatidylethanolamine (PE) concentrations (e.g., PE 16:0/20:5). Although increases in microbial-derived trimethylamine N-oxide suggest gastrointestinal lecithin degradation, elevations in plasma dimethylglycine, PC, LPC, and SM suggest that choline availability was improved by lecithin feeding in cows, thus supporting enhanced endogenous phospholipid synthesis.

Effect of dietary lipids and other nutrients on milk odd- and branched-chain fatty acid composition in dairy ewes.

Milk odd- and branched-chain fatty acids (OBCFA) are largely derived from bacteria leaving the rumen, which has encouraged research on their use as biomarkers of rumen function. Targeted research has examined relationships between these fatty acids (FA) and dietary components, but interactions between the effects of lipids and other nutrients on milk OBCFA are not well characterized yet. Furthermore, factors controlling milk OBCFA in sheep are largely unknown. Thus, the present meta-analysis examined relationships between diet composition and milk OBCFA using a database compiled with lot observations from 14 trials in dairy ewes fed lipid supplements. A total of 47 lots received lipid supplements, whereas their respective controls (27 lots) were fed the same basal diets without lipid supplementation. Relationships between milk OBCFA and dietary components were first assessed through a principal component analysis (PCA) and a correlation analysis. Then, responses of milk OBCFA to variations in specific dietary components (selected on the basis of the PCA) were examined in more detail by regression analysis. According to the loading plot, dietary unsaturated C18 FA loaded opposite to major milk OBCFA (e.g., 15:0, 15:0 anteiso, and 17:0) and were strongly correlated with principal component 1, which described 46% of variability. Overall, regression equations supported this negative, and generally linear, relationship between unsaturated C18 FA levels and milk OBCFA. However, the influence of C20-22 n-3 polyunsaturated FA and saturated FA was more limited. The PCA also suggested that dietary crude protein is not a determinant of milk OBCFA profile in dairy ewes, but significant relationships were observed between some OBCFA and dietary fiber or starch, consistent with a potential role of these FA as biomarkers of rumen cellulolytic and amylolytic bacteria. In this regard, regression equations indicated that iso FA would show opposite responses to increasing levels of acid detergent fiber (positive linear coefficients) and starch (negative linear coefficients). Lipid supplementation would not largely affect these associations, supporting the potential of OBCFA as noninvasive markers of rumen function under different feeding conditions (i.e., with or without lipid supplementation). Because consumption of these FA may have nutritional benefits for humans, the use of high-fiber/low-starch rations might be recommended to maintain the highest possible content of milk OBCFA in dairy sheep.

Transient reductions in milk fat synthesis and their association with the ruminal and metabolic profile in dairy cows fed high-starch, low-fat diets.

Sub-acute ruminal acidosis (SARA) is sometimes observed along with reduced milk fat synthesis. Inconsistent responses may be explained by dietary fat levels. Twelve ruminally cannulated cows were used in a Latin square design investigating the timing of metabolic and milk fat changes during Induction and Recovery from SARA by altering starch levels in low-fat diets. Treatments were (1) SARA Induction, (2) Recovery and (3) Control. Sub-acute ruminal acidosis was induced by feeding a diet containing 29.4% starch, 24.0% NDF and 2.8% fatty acids (FAs), whereas the Recovery and Control diets contained 19.9% starch, 31.0% NDF and 2.6% FA. Relative to Control, DM intake (DMI) and milk yield were higher in SARA from days 14 to 21 and from days 10 to 21, respectively (P < 0.05). Milk fat content was reduced from days 3 to 14 in SARA (P < 0.05) compared with Control, while greater protein and lactose contents were observed from days 14 to 21 and 3 to 21, respectively (P < 0.05). Milk fat yield was reduced by SARA on day 3 (P < 0.05), whereas both protein and lactose yields were higher on days 14 and 21 (P < 0.05). The ruminal acetate-to-propionate ratio was lower, and the concentrations of propionate and lactate were higher in the SARA treatment compared with Control on day 21 (P < 0.05). Plasma insulin increased during SARA, whereas plasma non-esterified fatty acids and milk ß-hydroxybutyrate decreased (P < 0.05). Similarly to fat yield, the yield of milk preformed FA (>16C) was lower on day 3 (P < 0.05) and tended to be lower on day 7 in SARA cows (P < 0.10), whereas yield of de novo FA (<16C) was higher on day 21 (P < 0.01) in the SARA group relative to Control. The t10- to t11-18:1 ratio increased during the SARA Induction period (P < 0.05), but the concentration of t10-18:1 remained below 0.5% of milk fat, and t10,c12 conjugated linoleic acid remained below detection levels. Odd-chain FA increased, whereas branched-chain FA was reduced during SARA Induction from days 3 to 21 (P < 0.05). Sub-acute ruminal acidosis reduced milk fat synthesis transiently. Such reduction was not associated with ruminal biohydrogenation intermediates but rather with a transient reduction in supply of preformed FA. Subsequent rescue of milk fat synthesis may be associated with higher availability of substrates due to increased DMI during SARA.

Tall fescue as an alternative to timothy fed with or without alfalfa to dairy cows.

Tall fescue might be an alternative to timothy in northeastern North America because of its tolerance of recurring drought periods and its good summer regrowth, but is not always considered as an option in dairy rations because of its possible lack of palatability. The objective of this study was to evaluate the effects on the performance of lactating dairy cows of (1) replacing timothy silage by tall fescue silage, offered as sole forage in the diet or in combination with alfalfa silage, and (2) feeding tall fescue as silage (35% dry matter, DM) or haylage (55% DM). Experimental diets with a forage-to-concentrate ratio of 70:30 were (1) 100% timothy silage (TS); (2) 100% tall fescue silage (TFS); (3) 55:45 timothy:alfalfa silages (TS + AS); (4) 55:45 tall fescue:alfalfa silages (TFS + AS); and (5) 100% tall fescue haylage (TFH). Fifteen Holstein cows in mid-lactation (5 fitted with a rumen fistula) were randomly assigned to treatments in a triple 5 × 5 Latin square design with treatment periods of 21 d. Preplanned contrasts were timothy versus tall fescue silages, sole grass species versus grass-alfalfa, interaction between sole grass species and grass-alfalfa, and TFS versus TFH. Grass species did not affect dry matter intake (DMI) or milk yield and fat concentration. Milk protein concentration was not affected by grass species when offered in combination with alfalfa, but it was higher with the TS diet than the TFS diet when offered as sole forages. Adding alfalfa to either tall fescue or timothy silage resulted in greater DMI and milk yield, but lower milk fat concentration, than when the grass silages were the sole forage in the diet. The molar proportion of propionate in the rumen was greater when cows were fed diets with tall fescue silage compared with timothy silage, which resulted in a lower acetate-to-propionate ratio. Milk fat concentrations of fatty acids from microbial origin, namely branched-chain fatty acids, were greater when grass silage, and especially timothy silage, were fed as sole forages rather than with alfalfa silage. Feeding TFH rather than TFS caused a decrease in DMI and tended to lower milk protein concentration, but did not affect milk yield. A more fibrolytic fermentation profile was observed in rumen of cows fed TFH compared with TFS, as indicated by the increase in the molar proportion of acetate and the higher acetate-to-propionate ratio in rumen fluid, and a concomitant increase in branched-chain fatty acid concentration in milk fat. Tall fescue as silage or haylage is a valuable alternative to timothy silage for lactating dairy cows.