Effects of feeding difructose anhydride on the mineral status and milking performance of transition cows.

The objective of this study was to assess the potential effect of difructose anhydride III (DFAIII) on calcemia, magnesemia, and milking performance in dairy cows. A total of 66 multiparous Holstein cows in late pregnancy (gestation days, mean ± SD = 253.8 ± 2.13 d) were blocked according to their expected calving date and randomly assigned to either receiving no supplementation (control) or receiving 40 g/d of DFAIII (DFA) between -14 and +7 d relative to calving following a complete randomized block design. Cows in the control group received 640 g/d of a pellet containing no DFAIII, whereas DFA cows received the same pellet but containing 6.25% DFAIII. Pellets of each treatment were top-dressed on a daily basis while cows were dry and were fed via an automatic feeding system twice daily (320 g each feeding) during milking. Dry cows were fed once a day, whereas lactating cows were fed twice daily. Dry matter intake was individually monitored on a daily basis. Cows were milked twice daily and milk production and milk protein and fat contents recorded at every milking. Cows were kept on the study until they reached 21 d postpartum. Cows were weighed at dry-off (∼45 d before study enrollment) and twice daily after calving at the exit of the milking parlor. Cows were blood sampled for subsequent determination of serum Ca and Mg concentrations 3 d before the expected calving date and at 6, 12, 24, and 48 h and 7 and 14 d after calving. We found no differences in DMI before calving, but DFA cows consumed more feed than control cows at ∼15 DIM. All cows lost BW after calving, but DFA cows lost slightly less BW during the first 5 DIM than control cows. Cows on DFAIII produced more milk at ∼10 DIM compared with control cows, and DFAIII cows produced more milk protein than control cows 3 d after calving. Serum Ca concentrations were not affected by DFAIII supplementation; however, serum Mg concentrations at 6, 12, and 24 h after calving were greater in DFA than in control cows. In all, DFAIII did not affect postpartum calcemia but improved magnesemia between 6 and 24 h after calving. Milk production in DFA cows was improved around 10 d after calving and milk protein yield after 3 d postpartum compared with control cows. The mechanism leading to increased Mg availability is not clear and warrants further research.

Changes in milk production and estimated income over feed cost of group-housed dairy cows when moved between pens.

Several studies have shown advantages of feeding cows in groups according to their nutrient requirements. However, there are concerns about losing milk when cows change from a high- to a low-nutrient diet. Data from 1,960 cows from 3 herds were analyzed to assess the impact on milk yield and estimated income over feed cost (IOFC) when moving cows between pens and rations. Pen feed intake and individual body weight and milk yield were recorded daily for 21 d before and 21 d after every pen movement. The data included 2,142 pen movements, and for each movement, milk production was recorded for 21 d before and 21 d after the change. Within farm, group, and cow, milk yield during the 21 d preceding a pen movement was used to predict milk yield for the subsequent 21 d using linear regression. Individual dry matter intake was estimated based on cow performance and diet composition, and then individual IOFC was calculated. Differences between actual and predicted milk yield and IOFC during the 21 d following a movement were determined and contrasted against zero using t-tests. In all 3 farms, every pen movement involved a change from a more expensive ration with more energy and protein than the one fed after the movement. On average, in all cases but one, observed milk yield was lower than the forecasted milk yield had cows not been moved. However, IOFC, on average, was positive in all cases except for 2 pen movements on 2 farms. Reasons for the improved IOFC with lower milk yield were due to a nutrient cost advantage, whereas, when IOFC decreased, differences in nutrient supply and dietary cost were not able to offset differences in milk yield. Moving cows according to milk production level does not result in economic advantages when the unit cost of nutrients is greater in the original than in the receiving ration. However, when the cost and nutrient difference between the diets offset potential losses in milk, forming groups according to production is advantageous.

Effects on rumen pH and feed intake of a dietary concentrate challenge in cows fed rations containing pH modulators with different neutralizing capacity.

Forty-five Holstein lactating cows (41 ± 8.8 kg/d of milk yield, 96 ± 35.6 days in milk, and 607 ± 80.4 kg of body weight) were enrolled in this study to assess the effects of diets supplemented with sodium bicarbonate or a magnesium-based product and their corresponding differences in dietary cation-anion difference (DCAD) on rumen pH, rumen microbial population, and milk performance of dairy cattle exposed to an induced decrease in rumen pH through a dietary challenge. Cows were randomly allocated to 3 total mixed rations (TMR) differing in the type of supplement to modulate rumen pH: (1) control, no supplementation; (2) SB, supplemented with 0.82% of sodium bicarbonate with a neutralizing capacity (NC) of 12 mEq/g; and (3) MG, supplemented with 0.25% of magnesium oxide (pHix-Up, Timab Magnesium) with a NC of 39 mEq/g. Thus, SB and MG rations had, in theory, the same NC. The 3 TMR differed for control, SB, and MG in their DCAD-S (calculated considering Na, K, Cl, and S), which was on average 13.2, 21.2, and 13.7 mEq/100 g, respectively, or DCAD-Mg (calculated accounting for Mg, Ca, and P), which was 31.4, 41.2, and 35.2 mEq/100 g, respectively. The study lasted 63 d, with the first 7 d serving as a baseline, followed by a fortnightly progressive decrease of dietary forage-to-concentrate ratio (FCR) starting at 48:52, then 44:56, then 40:60, and finishing at 36:64. Individual dry matter intake (DMI) was recorded daily. Seven cows per treatment were equipped with electronic rumen boluses to monitor rumen pH. Control and SB cows consumed less dry matter (DM; 23.5 ± 0.31 kg/d) than MG cows (25.1 ± 0.31 kg/d) when fed dietary FCR of 44:56 and 40:60. Energy-corrected milk decreased from 40.8 ± 1.21 to 39.5 ± 1.21 kg/d as dietary FCR decreased, independently of dietary treatments. Rumen pH decreased and the proportion of the day with rumen pH <5.8 increased as dietary FCR decreased, and at low dietary FCR (i.e., 36:64) rumen pH was greater in MG cows than in control and SB cows. Reducing the DCAD-S from 28 to 18 mEq/100 g or the DCAD-Mg from 45 to 39 mEq/kg had no effects on DMI or milk yield. Cows supplemented with ∼62 g/d of magnesium oxide (pHix-Up) maintained a greater rumen pH and consumed more DM than cows supplemented with ∼200 g/d of sodium bicarbonate when fed a diet with low FCR.

Symposium review: Decomposing efficiency of milk production and maximizing profit.

The dairy industry has focused on maximizing milk yield, as it is believed that this maximizes profit mainly through dilution of maintenance costs. Efficiency of milk production has received, until recently, considerably less attention. The most common method to determine biological efficiency of milk production is feed efficiency (FE), which is defined as the amount of milk produced relative to the amount of nutrients consumed. Economic efficiency is best measured as income over feed cost or gross margin obtained from feed investments. Feed efficiency is affected by a myriad of factors, but overall they could be clustered as follows: (1) physiological status of the cow (e.g., age, state of lactation, health, level of production, environmental conditions), (2) digestive function (e.g., feeding behavior, passage rate, rumen fermentation, rumen and hindgut microbiome), (3) metabolic partitioning (e.g., homeorhesis, insulin sensitivity, hormonal profile), (4) genetics (ultimately dictating the 2 previous aspects), and (5) nutrition (e.g., ration formulation, nutrient balance). Over the years, energy requirements for maintenance seem to have progressively increased, but efficiency of overall nutrient use for milk production has also increased due to dilution of nutrient requirements for maintenance. However, empirical evidence from the literature suggests that marginal increases in milk require progressively greater marginal increases in nutrient supply. Thus, the dilution of maintenance requirements associated with increases in production is partially overcome by a progressive diminishing marginal biological response to incremental energy and protein supplies. Because FE follows the law of diminishing returns, and because marginal feed costs increase progressively with milk production, profits associated with improving milk yield might, in some cases, be considerably lower than expected.

Short communication: Recombinant mammary serum amyloid A3 as a potential strategy for preventing intramammary infections in dairy cows at dryoff.

Mammary serum amyloid A3 (M-SAA3) has shown potential in stimulating innate immunity during intramammary infections, at calving and at dryoff. In this study, we produced recombinant caprine M-SAA3 to test its ability to reduce intramammary infections with Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and Escherichia coli, which are all common mastitis-producing pathogens. Recombinant production of M-SAA3 (followed by lipopolysaccharide removal to avoid lipopolysaccharide-nonspecific stimulation of the immune system) was successfully achieved. Mammary serum amyloid A3 stimulated the expression of IL-8 in a dose-dependent manner in primary mammary cultures. Although a direct killing effect on Staph. aureus by M-SAA3 was not detected, this acute phase protein was able to reduce Staph. aureus, Strep. uberis, and Strep. dysgalactiae infections by up to 50% and induced a reduction in E. coli counts of 67%. In general, the best concentration of caprine M-SAA3 for inhibiting infections was the lowest concentration tested (10 µg/mL), although higher concentrations (up to 160 µg/mL) increased its antimicrobial potential against some pathogens.

Modulation of rumen pH by sodium bicarbonate and a blend of different sources of magnesium oxide in lactating dairy cows submitted to a concentrate challenge.

With the objective of evaluating the potential effects of sodium bicarbonate or a magnesium-based product on rumen pH and milk performance of dairy cattle exposed to a dietary challenge, 30 lactating Holstein cows (648 ± 67 kg of body weight; 44.4 ± 9.9 kg/d of milk yield; 155 ± 75 d in milk) were blocked by parity (9 primiparous and 21 multiparous) and randomly distributed to 3 treatment groups. One group received a total mixed ration (TMR) that acted as a control (CTR), a second group (SB) received the same TMR but with an additional supplementation of 0.8% of sodium bicarbonate, and a third group (MG) received the same TMR as CTR but an additional supplementation of 0.4% of a magnesium-based product (pHix-Up, Timab, Dinard, France). After 1 wk of exposure to this TMR, all 3 rations were supplemented with 1 kg/d of barley, which was then increased 1 kg/wk until reaching 3 kg/d of barley during wk 4 of the study. Every kilogram of barley replaced 1 kg of forage in the diet. Individual feed intake and behavior were monitored using electronic feed bins. Seven cows per treatment were equipped with an intraruminal bolus that recorded pH every 15 min. As the severity of the barley challenge increased, dry matter intake decreased, but this decrease was more pronounced in SB cows than in MG cows, with an intermediate response for CTR cows. The MG cows produced more milk when challenged with 2 or 3 kg/d of additional barley than when challenged with 1 kg/d, whereas CTR cows produced less milk with the 3 kg/d challenge compared with 1 or 2 kg/d, and the SB cows maintained milk production. Milk fat content decreased with barley challenges, with CTR cows experiencing a more severe decrease than SB cows, which maintained stable butterfat values throughout the study, and MG cows showed a decline in milk fat content only with the 3 kg/d of additional barley. Meal size was also reduced as the severity of barley challenge increased, and this reduction was more modest in MG cows than in SB cows. The number of daily meals consumed by SB and MG cows was more constant than that recorded in CTR cows. Cows on the CTR and SB treatments showed a marked decrease in rumen pH with the 3 kg/d of additional barley, whereas MG cows maintained stable rumen pH during the barley challenges and had greater average rumen pH (5.93 ± 0.04) than CTR cows (5.83 ± 0.04) with the 3 kg/d of additional barley; SB cows showed intermediate values (5.85 ± 0.04). Last, MG cows spent less time (32.3 ± 6.1%) with rumen pH ≤5.8 when exposed to the 3 kg/d of barley challenge than CTR and SB cows (50.7 ± 5.02%). In conclusion, supplementation with MG prevents the decline in dry matter intake and milk production induced by a rumen challenge, whereas supplementation with SB prevents the decay in milk production but does not prevent the decrease in feed intake. These changes were probably due to the ability of the MG treatment to prevent a reduction in rumen pH when challenging cows with 3 kg/d of additional barley in the ration.

Trends in recombinant protein use in animal production.

Recombinant technologies have made possible the production of a broad catalogue of proteins of interest, including those used for animal production. The most widely studied proteins for the animal sector are those with an important role in reproduction, feed efficiency, and health. Nowadays, mammalian cells and fungi are the preferred choice for recombinant production of hormones for reproductive purposes and fibrolytic enzymes to enhance animal performance, respectively. However, the development of low-cost products is a priority, particularly in livestock. The study of cell factories such as yeast and bacteria has notably increased in the last decades to make the new developed reproductive hormones and fibrolytic enzymes a real alternative to the marketed ones. Important efforts have also been invested to developing new recombinant strategies for prevention and therapy, including passive immunization and modulation of the immune system. This offers the possibility to reduce the use of antibiotics by controlling physiological processes and improve the efficacy of preventing infections. Thus, nowadays different recombinant fibrolytic enzymes, hormones, and therapeutic molecules with optimized properties have been successfully produced through cost-effective processes using microbial cell factories. However, despite the important achievements for reducing protein production expenses, alternative strategies to further reduce these costs are still required. In this context, it is necessary to make a giant leap towards the use of novel strategies, such as nanotechnology, that combined with recombinant technology would make recombinant molecules affordable for animal industry.

Robotic milking: Feeding strategies and economic returns.

Cows in herds equipped with conventional milking parlors follow a structured, consistent, and social milking and feeding routine. Furthermore, in most cases cows in conventional herds receive all their nutrients from a total mixed ration, whereas in herds equipped with robotic or automatic milking systems (AMS) a fraction of their nutrients is provided during milking, mainly as a means to attract cows to the milking system. In this regards, AMS present both a challenge and an opportunity for feeding cows. The main challenge resides in maintaining a minimum and relatively constant milking frequency in AMS. However, milking frequency is dependent on many factors, including the social structure of the herd, the farm layout design, the type of traffic imposed to cows, the type of flooring, the health status of the cow (especially lameness, but also mastitis, metritis, among others), the stage of lactation, the parity, and the type of ration fed at the feed bunk and the concentrate offered in the AMS. Uneven milk frequency has been associated with milk losses and increased risk of mastitis, but most importantly it is a lost opportunity for milking the cow and generating profit. On the other hand, the opportunity from AMS resides in the possibility of milking more frequently and feeding cows more precisely or more closely to their nutrient needs on an individual basis, potentially resulting in a more profitable production system. But, feeding cows in the parlor or AMS has many challenges. On one side, feeding starchy, highly palatable ingredients in large amounts may upset rumen fermentation or alter feeding behavior after milking, whereas feeding high-fiber concentrates may compromise total energy intake and limit milking performance. Nevertheless, AMS (and some milking parlors, especially rotary ones) offer the possibility of feeding the cows to their estimated individual nutrient needs by combining different feeds on real time with the aim of maximizing profits rather than milk yield. This approach requires that not only the amount of feed offered to each cow but also the composition of the feed vary according to the different nutrient needs of the cows. This review discusses the opportunities and pitfalls of milking and feeding cows in an AMS and summarizes different feeding strategies to maximize profits by managing the nutrition of the cows individually.

A combination of lactic acid bacteria regulates Escherichia coli infection and inflammation of the bovine endometrium.

Uterine function in cattle is compromised by bacterial contamination and inflammation after calving. The objective of this study was to select a combination of lactic acid bacteria (LAB) to decrease endometrium inflammation and Escherichia coli infection. Primary endometrial epithelial cells were cultured in vitro to select the most favorable LAB combination modulating basal tissue inflammation and E. coli infection. Supernatants were obtained to determine expression of pro-inflammatory cytokines, and E. coli infection was evaluated after harvesting the tissue and plate counting. The selected LAB combination was tested in uterus explants to assess its capacity to modulate basal and acute inflammation (associated with E. coli infection). The combination of Lactobacillus rhamnosus, Pediococcus acidilactici, and Lactobacillus reuteri at a ratio of 25:25:2, respectively, reduced E. coli infection in vitro with (89.77%) or without basal tissue inflammation (95.10%) compared with single LAB strains. Lactic acid bacteria treatment reduced CXCL8 and IL1B expression 4.7- and 2.2-fold, respectively, under acute inflammation. Ex vivo, the tested LAB combination reduced acute inflammation under E. coli infection, decreasing IL-8, IL-1ß, and IL-6 up to 2.2-, 2.5-, and 2.2-fold, respectively. In the total inflammation model, the LAB combination decreased IL-8 1.6-fold and IL-6 1.2-fold. Ultrastructural evaluation of the tissue suggested no direct interaction between the LAB and E. coli, although pathological effects of E. coli in endometrial cells were greatly diminished or even reversed by the LAB combination. This study shows the promising potential of LAB probiotics for therapeutic use against endometrial inflammation and infection.

Influence of milk processing temperature on growth performance, nitrogen retention, and hindgut's inflammatory status and bacterial populations in a calf model.

This research communication describes a study aimed at evaluating the effects of heat treatment of milk on growth performance, N retention, and hindgut's inflammatory status and bacterial populations using young dairy calves as a model. Twenty-one Holstein calves were randomly allocated to one of three treatments: raw milk (RM), pasteurised milk (PAST), or UHT milk (UHT). Calves were submitted to a N balance study, and a biopsy from the distal colon and a faecal sample were obtained from 5 animals per treatment to determine expression of several genes and potential changes in the hindgut's bacterial population. Milk furosine content was 33-fold greater in UHT than in RM and PAST milks. Calves receiving RM grew more than those fed UHT, and urinary N excretion was greatest in calves fed UHT. Quantification of Lactobacillus was lower in calves consuming PAST or UHT, and Gram negative bacteria were greater in UHT than in PAST calves. The expression of IL-8 in the hindgut's mucosa was lowest and that of IL-10 tended to be lowest in RM calves, and expression of claudin-4 tended to be greatest in UHT calves. In conclusion, the nutritional value of UHT-treated milk may be hampered because it compromises growth and increases N excretion in young calves and may have deleterious effects on the gut's bacterial population and inflammation status.

Back to basics: Precision while mixing total mixed rations and its impact on milking performance.

Details from every mixing load of total mixed ration (TMR) fed to ∼19,000 cows distributed in 92 pens from 21 farms, along with individual milk yield of each cow in every pen and farm, were collected from a feeding and management system (algoMilk; www.algomilk.com) between 2020 and 2022 on a daily basis to assess the impact of quality of mixing TMR on animal performance. Divergence between expected and actual amounts of ingredients mixed in every load was calculated and expressed as a percentage relative to expected amounts. Ingredients were classified as (1) energy grains (i.e., corn, wheat), (2) protein sources (i.e., soybean meal, canola meal), (3) hays (i.e., alfalfa hay), (4) grain silages (i.e., corn silage), (5) nongrain silages (i.e., alfalfa silage), (6) minerals (i.e., salt, sodium bicarbonate), and (7) straw (i.e., wheat straw). Milk yield was averaged within farm and pen on a weekly basis, and mixing divergences were also averaged by load or by ingredient type and week within pen and farm. The weekly standard deviation (SD) of mixing divergences was calculated for every pen and farm. The average divergence of the total amount of TMR prepared was 1.52 ± 0.017% (mean ± SD), which means that, in general, mixing errors were caused by adding an excess of one or more ingredients. Energy grains (1.20 ± 0.037%), grain silages (1.78 ± 0.023%), hays (2.29 ± 0.044%), and protein sources (1.82 ± 0.043%) were mixed in excessive amounts (mean ± SD), whereas nongrain silages (-1.5 ± 0.037%), molasses (-3.05 ± 0.067%), minerals (96.9 ± 0.084%), and straw (-0.6 ± 0.063%) were mixed (mean ± SD) in lower amounts than expected. Divergence in the total amount of TMR was weakly quadratically (concave) correlated (R2 = 0.04) with milk yield. Similarly, divergence in the amounts of grains, protein sources, hay, silages, minerals, and molasses mixed in the TMR wagon in relation to the formulated ration was also weakly and quadratically (concave) with milk yield. Minimizing mixing errors may have positive effects on milking performance.

Key performance indicators used by dairy consultants during the evaluation of reproductive performance during routine visits.

Dairy farms need thorough and efficient reproduction control. Consultants specialized in reproduction use key performance indicators (KPI) to monitor the reproductive performance of farms and must be able to decipher between the approach in a first visit and routine visits. A total of 49 consultants specialized in dairy reproduction from 21 countries responded to an online survey conducted to determine the most suitable parameters during routine visits every 2 to 4 weeks. The survey was comprised of 190 questions, 178 of them rated from 0 (irrelevant) to 10 (maximum importance) points. The questions were divided into five sections: (1) consultant and farm model, (2) general data of the farm, (3) cow reproduction, (4) postpartum and metabolic disease, and (5) heifer reproduction. The median, interquartile range, minimum and maximum values, and 95% confidence interval were determined for each question. Afterward, a multivariate analysis, using between-group linkage via Ward's hierarchical clustering was conducted to generate clusters of consultants according to their response pattern. Finally, a chi-square test was conducted to assess the association between years of experience of the consultant and farm size within the clusters generated in each section of the questionnaire. The majority of the consultants considered 34 parameters to be highly important (rated 8-10) to analyze during routine visits. The consultants used several KPI (in variable quantitative range) to evaluate any of the presented sections and considered that all the five sections are critical to control. They are aware of using KPI that reflect heat detection, fertility, and farming efficiency as well as KPI that can provide information on reproductive efficiency in the near future for cows, such as postpartum and metabolic diseases. However, parameters that are relatively old and ineffective, in terms of reproductive performance control, are still highly regarded by the majority of consultants in a routine-visit scenario. Farm size and years of experience of the consultant did not influence the type or number of parameters chosen as KPI during routine visits. The parameters rated with the highest importance (rate 10) that could be considered for an easy, fast, and universal use in routine visits to assess the reproductive status were: First service CR (%), Overall pregnancy rate (%) for cows, and age at first calving (d) for heifers.

Difructose Anhydride and Passive Immunity Effects on Passive Immune Transfer and Performance of Feeding Difructose Anhydride to Neonatal Calves.

The objective of this study was to assess the potential effects of supplementing difructose anyhdride III (DFAIII) during the first days of life on the absorption of immunoglobulin G (IgG) and growth performance of calves early in life fed colostrum with a high IgG concentration. Sixty-six healthy new-born Holstein calves were randomly assigned to three treatments consisting of no supplementation (control), supplementation of 12 g/d (DFA12), or 36 g/d (DFA36) of DFAIII during the first 7 d of life via colostrum and milk replacer (MR). Calves were separated from dams at birth and bottle-fed colostrum in two meals, each targeting 2.5 L within the first 18 h of birth. Colostrum had been previously collected from other dams (and preserved frozen) within the first 2 h of calving and had a Brix value ≥32%. Daily consumption of starter concentrate and MR (and colostrum on the first day) were individually monitored. Calves were body weighed using an electronic scale at birth and on a weekly basis thereafter until the end of study at 42 d of age. A sample of colostrum fed to each calf and a blood sample from the jugular vein of the calves were collected at 12 and 24 h of life to determine the IgG concentration. The mean colostrum IgG concentration fed in the current study was 110 ± 33.7 g/L (mean ± SD). No differences in animal performance were found among the treatments. Calves on all treatments consumed the same amount of colostrum with a similar concentration of IgG, and thus the amount of IgG consumed was also similar. Serum IgG concentrations were greater at 24 than at 12 h but did not differ among treatments. However, the apparent efficiency of absorption of colostral immunoglobulins was greater in DFA12 and DFA36 at 12 h of life than in control calves, with no differences observed at 24 h. Even when feeding high-quality colostrum, in terms of IgG concentration, supplementation with difructose anhydride III may pose an additional advantage in promoting the passive transfer of immunoglobulins in neonatal Holstein calves during the first 12 h of life.

Modulation of milking performance, methane emissions, and rumen microbiome on dairy cows by dietary supplementation of a blend of essential oils.

Cattle represent a high contribution of the livestock's greenhouse gas emissions, mainly in the form of methane. Essential oils are a group of plant secondary metabolites obtained from volatile fractions of plants that have been shown to exert changes in the rumen fermentation and may alter feed efficiency and to reduce methane production. The objective of this study was to investigate the effect on rumen microbial population, CH4 emissions and milking performance of a mixture of essential oils (Agolin Ruminant, Switzerland) incorporated daily in the ration of dairy cattle. Forty Holstein cows (644 ± 63.5 kg of BW producing 41.2 ± 6.44 kg/d of milk with 190 ± 28.3 DIM) were divided into two treatments (n = 20) for 13 wk and housed in a single pen equipped with electronic feeding gates to control access to feed and monitor individual DM intake (DMI) on a daily basis. Treatments consisted of no supplementation (Control) or supplementation of 1 g/d of a blend of essential oils (BEOs) fed in the TMR. Individual milk production was recorded using electronic milk meters on a daily basis. Methane emissions were recorded using sniffers at the exit of the milking parlour. At day 64 of the study, a sample of rumen fluid was collected from 12 cows per treatment after the morning feeding using a stomach tube. There were no differences in DMI, milk yield, or milk composition between the two treatments. However, cows on BEO exhaled less CH4 (444 ± 12.5 l/d) than cows on Control (479 ± 12.5 l/d), and exhaled less (P < 0.05) CH4/kg of DM consumed (17.6 vs 20.1 ± 0.53 l/kg, respectively) from the first week of study, with no interaction with time, which suggests a fast action of BEO of CH4 emissions. Rumen relative abundance of Entodonium increased, and those of Fusobacteria, Chytridiomycota, Epidinium, and Mogibacterium decreased in BEO compared with Control cows. Supplementing 1 g/d of BEO reduces CH4 emissions on absolute terms (l/d) and diminishes the amount of CH4 produced by unit of DM consumed by cows relatively soon after the first supplementation, and the effect is sustained over time without impacting intake or milking performance.

Key Performance Indicators Used by Dairy Consultants During the Evaluation of Reproductive Performance in a First Visit.

Reproduction plays a fundamental role in the profitability of dairy farms. Consultants use key performance indicators (KPI) to monitor the reproductive performance of the farms. They must decipher between the most suitable ones to face two different scenarios that may need the analysis of different parameters: (1) approach in a first visit, and (2) routine visits. Forty-nine consultants specialized in dairy reproduction from 21 countries responded to an online survey conducted to determine the most suitable parameters in a first visit approach. The survey was comprised of 190 questions, 178 of them rated from 0 (irrelevant) to 10 (maximum importance) points. The questions were divided into 5 sections: (1) consultant and farm model, (2) general data of the farm, (3) cow reproduction, (4) postpartum and metabolic disease, and (5) heifer reproduction. The median, interquartile range, minimum and maximum values, and 95% confidence interval (CI) were determined for each question. Afterward, a multivariate analysis, using between-group linkage via Ward's hierarchical clustering was conducted to generate clusters of consultants according to their response pattern. Lastly, a Chi-square test was conducted to assess the association between the years of experience of the consultant and farm size within the clusters generated in each section of the questionnaire. Most of the consultants considered 27 parameters to be highly important to analyze during the first visit. Consultants use several KPIs (in variable quantitative range) to evaluate any of the presented sections. Moreover, consultants preferred parameters focused on heat detection, fertility, and pregnancy achievement regarding the production cycle of a dairy cow. Consultants also showed high interest in obtaining a general overview of milk production, farming efficiency, and the heifer rearing process; but the farm size and the years of experience of the consultant influenced the type and number of parameters chosen as KPI. The parameters rated with the highest importance (rate 10) that could be considered for an easy, fast, and universal first visit to assess the reproductive status were: first service conception rate, overall pregnancy rate, and 21d pregnancy rate for cows, and age at first calving for heifers.

Longitudinal Study of Fecal Microbiota in Calves with or without Diarrhea Episodes before Weaning.

The microbiota plays an important role in the development of diarrhea in pre-weaned calves. The characterization of the fecal microbiota in health and disease can be critical to unravel the bacterial dynamics associated with diarrhea and help with its prevention and control. In this study, we aimed to detect changes in the fecal microbiota of calves that experienced early-life diarrhea episodes. Fecal samples were taken from calves remaining healthy and calves with an episode of diarrhea during the study. We sampled at arrival (12 days of age) and after one and two months of life; also, at the time of the diarrhea episode for the diarrheic calves (day 17). Samples were processed to extract total DNA, submitted to 16S rRNA gene sequencing, and bioinformatically analyzed to infer the bacterial populations. Microbiota changes through time were reported for both groups. However, we detected an earlier stabilization in the healthy group. Moreover, we detected changes within low abundant taxa that may play a role in the subsequent health status of the animals. The fecal microbiota of healthy and diarrheic calves showed different dynamics in the diversity through time that may be the reflections of the variations within low-abundant taxa.

Potential of Oral Nanoparticles Containing Cytokines as Intestinal Mucosal Immunostimulants in Pigs: A Pilot Study.

Antimicrobial resistance is a global threat that is worryingly rising in the livestock sector. Among the proposed strategies, immunostimulant development appears an interesting approach to increase animal resilience at critical production points. The use of nanoparticles based on cytokine aggregates, called inclusion bodies (IBs), has been demonstrated as a new source of immunostimulants in aquaculture. Aiming to go a step further, the objective of this study was to produce cytokine nanoparticles using a food-grade microorganism and to test their applicability to stimulate intestinal mucosa in swine. Four cytokines (IL-1ß, IL-6, IL-8, and TNF-α) involved in inflammatory response were produced recombinantly in Lactococcus lactis in the form of protein nanoparticles (IBs). They were able to stimulate inflammatory responses in a porcine enterocyte cell line (IPEC-J2) and alveolar macrophages, maintaining high stability at low pH and high temperature. In addition, an in vivo assay was conducted involving 20 piglets housed individually as a preliminary exploration of the potential effects of IL-1ß nanoparticles in piglet intestinal mucosa after a 7 d oral administration. The treated animals tended to have greater levels of TNF-α in the blood, indicating that the tested dose of nanoparticles tended to generate an inflammatory response in the animals. Whether this response is sufficient to increase animal resilience needs further evaluation.

The Potential of Metalloproteinase-9 Administration to Accelerate Mammary Involution and Boost the Immune System at Dry-Off.

The dry period is decisive for the milking performance of dairy cows. The promptness of mammary gland involution at dry-off affects not only the productivity in the next lactation, but also the risk of new intra-mammary infections since it is closely related with the activity of the immune system. Matrix metalloproteinase-9 (MMP-9) is an enzyme present in the mammary gland and has an active role during involution by disrupting the extracellular matrix, mediating cell survival and the recruitment of immune cells. The objective of this study was to determine the potential of exogenous administration of a soluble and recombinant version of a truncated MMP-9 (rtMMP-9) to accelerate mammary involution and boost the immune system at dry-off, avoiding the use of antibiotics. Twelve Holstein cows were dried abruptly, and two quarters of each cow received an intra-mammary infusion of either soluble rtMMP-9 or a positive control based on immunostimulant inclusion bodies (IBs). The contralateral quarters were infused with saline solution as negative control. Samples of mammary secretion were collected during the week following dry-off to determine SCC, metalloproteinase activity, bovine serum albumin, lactoferrin, sodium, and potassium concentrations. The soluble form of rtMMP-9 increased endogenous metalloproteinase activity in the mammary gland compared with saline quarters but did not accelerate either the immune response or involution in comparison with control quarters. The results demonstrated that the strategy to increase the mammary gland immunocompetence by recombinant infusion of rtMMP-9 was unsuccessful.

Effects of acarbose on ruminal fermentation, blood metabolites and microbial profile involved in ruminal acidosis in lactating cows fed a high-carbohydrate ration.

The objective was to evaluate the effects of an inhibitor of alpha-amylase and glucosidase (acarbose, Pfizer Limited, Corby, UK) on ruminal fermentation, blood metabolism and microbial profile in dairy cows in a 2x2 cross-over experiment. Eight Holstein cows fitted with rumen cannulas (milk yield, 24.3+/-2.35 kg/d, body weight, 622+/-54 kg, days in milk, 183+/-67, 5 multiparous and 3 primiparous) were used. Treatments were: control (no additive, CTR) and alpha-amylase and glucosidase inhibitor (0.75 g acarbose-premix/cow per d, AMI). Animals were given ad-libitum access to a high non-fibre carbohydrate (NFC) partial mixed ration (PMR) containing 17.6% crude protein, 28.3% neutral detergent fibre, and 46.5% NFC in the dry matter and supplementary concentrate during milking. Blood samples were taken to determine blood glucose, insulin and urea within the first hour after the morning feeding on two separate days in each period. Samples of ruminal contents were collected during 3 d in each period at 0, 4 and 8 h after feeding to determine volatile fatty acid and ammonia-N concentrations and to quantify protozoa, Streptococcus bovis and Megasphaera elsdenii. Rumen pH was recorded electronically at 22-min intervals during 6 d in each period. Results were analysed using a mixed-effects model. Cows on AMI treatment spent less time with ruminal pH <5.6 compared with cows in the CTR group (3.74 and 6.52+/-0.704 h/d, respectively). Cows in the AMI group had greater daily average pH compared with those in the CTR group (6.05 and 5.92+/-0.042, respectively). AMI animals tended (P=0.09) to have lower Str. bovis to Meg. elsdenii ratio than CTR (4.09 and 26.8+/-12.0, respectively). These results indicate that dietary supplementation with acarbose in dairy cattle fed high-production rations may be effective in reducing the time for which rumen pH is suboptimal, with no negative effects on ruminal fermentation and blood metabolites.

A Meta-analysis Describing the Effects of the Essential oils Blend Agolin Ruminant on Performance, Rumen Fermentation and Methane Emissions in Dairy Cows.

There is an increasing pressure to identify feed additives which increase productivity or decrease methane emissions. This paper aims to elucidate the effects of supplementing a specific essential oils blend Agolin® Ruminant on the productivity of dairy cows in comparison to non-treated animals. A total of 23 in vivo studies were identified in which Agolin was supplemented at 1 g/d per cow; then a meta-analysis was performed to determine the response ratio on milk yield, rumen fermentation, methane emissions and health. Results indicated that an adaptation period of at least 4 weeks of treatment is required. Whereas short-term studies showed minor and inconsistent effects of Agolin, long-term studies (>4 weeks of treatment) revealed that Agolin supplementation increases milk yield (+3.6%), fat and protein corrected milk (+4.1%) and feed efficiency (+4.4%) without further changes in milk composition and feed intake. Long-term treatment also decreased methane production per day (-8.8%), per dry matter intake (-12.9%) and per fat and protein corrected milk yield (-9.9%) without changes in rumen fermentation pattern. In conclusion, despite the mode of action is still unclear and the small number of studies considered, these findings show that Agolin represents an encouraging alternative to improve productivity in dairy cows.