Diego Antonio Mattiauda

The objective of this study was to evaluate the effects of sodium monensin (MON) and a phytochemical mixture (PHY) in dairy cows grazing alfalfa and supplemented with total mixed rations (TMR) on the: 1) neutral detergent fiber (NDF) degradability of alfalfa hay (AH), 2) in-situ organic matter digestibility (ISDom) of different feeds (four cultivated pastures, AH, pre- and postpartum TMR, and a simulated diet of alfalfa+postpartum TMR), and 3) ruminal fermentation profile. Nine rumen-fistulated Holstein cows were randomly assigned to one of three treatments: control (C), MON (0.30 g/cow/day), or PHY (50 g/cow/day). Additives were incorporated into the concentrate portion of the TMR from 30 days prepartum to 60 days postpartum. NDF degradation kinetics of AH and ISDom were determined between days 56 and 60 postpartum. Rumen fluid was collected at 0, 4, 8, 16, and 24 h after feeding to measure pH, ammonia nitrogen (NH3-N), volatile fatty acids (VFA), and protozoa counts. Both additives reduced the ISDom of the prepartum TMR (P<0.05) and the NDF degradation rate of AH (P<0.05) without affecting its potential degradability. They also promoted a more gluconeogenic VFA profile (P<0.05) and decreased protozoa counts (P<0.05). PHY further reduced NH3-N concentrations compared with MON and C (P<0.05). In conclusion, MON and PHY improved ruminal fermentation efficiency without affecting the potential for NDF degradation and PHY additionally enhanced nitrogen utilization, highlighting its potential as a natural alternative to MON in pasture-based dairy systems supplemented with mixed rations.

Sward structure and post-grazing heights (SH) significantly influence plant growth and animal intake, crucial for dairy grazing systems. However, these interactions are dynamic and vary with season, resource heterogeneity, and defoliation patterns. Seasonal effects of control (TC), medium (TM), and lax (TL) post-grazing SH of grazed Lolium arundinaceum-based pasture on forage production and utilization, herbage mass, green cover, and chemical composition were tested during autumn-winter and spring seasons and among tall (TP), medium (MP), and short (SP) patches in spring. Thirty-six lactating Holstein cows were randomized evenly to TC, TM, and TL grazing treatments to achieve 6, 9, and 12 cm of post-grazing SH during autumn-winter, and 9, 12, and 15 cm in spring. Forage production was higher on TL than TM and TC, yet utilization was similar across all treatments. The TP relative to MP on SP increased for TL compared to TC and TM. The TP-TC presented higher leaf-density and leaf-proportion, than TP-TL, without modifying leaf canopy distribution of superior-medium horizons among treatments. Grazing management modulated forage production and structural heterogeneity across SH treatments. Critically, monitoring patch-level dynamics—rather than mean height—is essential for optimizing production and harvest efficiency in temperate systems by improving grazing horizon accessibility.

This study evaluated the effects of three treatments in dairy cows under pasture‐based systems during the transition and early lactation periods: one group supplemented with a phytochemical mix (polyphenols, curcuminoids, piperine, and trans‐cinnamaldehyde, PHY), another group supplemented with monensin (MON), and a third group with no additive, used as the control (CTL). Sixty Holstein cows (primiparous and multiparous) were assigned to these treatments from 30 days prepartum to 60 days postpartum. Productive, metabolic, endocrine, hematological, and reproductive parameters were analyzed. Results showed that both PHY and MON increased milk yield in primiparous cows compared to CTL, whereas no treatment differences were observed in multiparous cows. MON supplementation was associated with higher serum cholesterol concentrations, particularly in primiparous cows. Total leukocyte counts did not differ between treatments; however, a treatment effect was observed for monocytes in multiparous cows. Energy balance indicators (nonesterified fatty acids, beta‐hydroxybutyrate, and glucose) and calcium and phosphorus were not significantly influenced by treatments and remained within physiological ranges. In conclusion, both MON and the phytochemical mix supported adaptation during the transition period, although their effects differed by parity and physiological response. MON was more closely associated with lipid metabolism, while the phytochemical mix may have contributed to subtle immune‐related adjustments, warranting further investigation.

Phytochemicals are a potential alternative to antibiotic growth promoters. This study evaluated the effects of phytochemicals (curcuminoids, trans-cinnamaldehyde, and piperine) and monensin on performance and ruminal fermentation during the transition period in grazing dairy cows. In a complete randomized design, 60 Holstein cows (36 multiparous, 24 primiparous; 9 fistulated) were assigned to (1) control (CTL), (2) monensin (MON, 0.30 g/cow/day), or (3) phytochemicals (PHY, 50 g/cow/day) treatment from 30 days prepartum to 60 days postpartum. Prepartum, cows received a total mixed ration (TMR); postpartum, they grazed between a.m. and p.m. milking and were supplemented with TMR. Ruminal fermentation was evaluated at −7, 30, and 60 days postpartum. Prepartum dry matter intake was lower in MON primiparous cows than in CTL and PHY. Additives increased milk yield and lactose percentage in primiparous cows. PHY cows had lower acetate, higher propionate, and reduced acetate-to-propionate and ketogenic-to-glucogenic ratios at 60 days postpartum. MON reduced prepartum protozoa, while PHY increased prepartum branched-chain volatile fatty acids (BCVFAs). Both additives decreased BCVFA and protozoa postpartum. Additives reduced ammonia at 30 days, but only PHY persisted at 60 days. MON and PHY improved primiparous performance, enhanced ruminal fermentation, and promoted glucogenic fermentation while reducing ammonia and protozoa.

In mixed systems (pasture plus TMR), it is essential to provide the cows with good housing conditions at times of supplementation during confinement. However, given that there are different types of confinement for high‐producing cows in pastoral‐based systems, it is necessary to determine how such confinement conditions can affect their welfare. The aim of this study was to determine if the type of confinement (compost barn (CB) versus outdoor soil‐bedded (OD)) used in mixed systems affects the welfare of dairy cows through behavioral and biochemical indicators. Holstein cows ( n = 32) calving in autumn were assigned to two treatments (CB or OD) at calving. During confinement (half a day) in CB, the cows were kept indoors with a compost bed (13.5 m ² /cow), including ventilation, while OD cows were kept in the open space with a dirt floor and shaded area (4.8 m ² /cow). Confinement and grazing behavior (eating, ruminating, drinking, lying, standing, and walking) and the number of agonistic interactions in confinement were recorded every 10 min, on 3 days within a week for 5 months. Blood was collected to determine the concentration of creatine kinase, total proteins, and albumin during lactation. During confinement, cows in CB were found to be more frequently eating ( p = 0.07), drinking ( p < 0.0001), and lying down ( p = 0.003) than those in OD, while OD cows were more time ruminating ( p = 0.0005), standing ( p = 0.02), and walking ( p < 0.0001). During pasture access, cows in CB were more time eating ( p = 0.01) and standing ( p = 0.0003), while they were less lying ( p = 0.01) than cows in the OD and no differences were found in ruminating, drinking, and walking behaviors. CB cows tended to present more agonist interactions than in OD cows ( p = 0.09). Cows in CB had higher total proteins ( p = 0.02) and globulins ( p = 0.006) than cows in OD. In conclusion, the type of confinement differentially affected the different behavioral indicators (lying, standing, walking, rumination, and agonist interactions), as well as blood concentration of total protein and globulins. Although CB did not have all the behavioral indicators of welfare in its favor for autumn‐calving cows (ruminating and agonist interactions), blood indicators (total protein and globulins) highlight advantages of CB in relation to OD.

The objective of the project was to identify feeding strategies under grazing, to improve the efficiency of the use of feeding resources, especially the pasture. The research strategy involved 4 experiments, where effect of access time to pasture and time of grazing allocation and timing of corn silage supplementation on productive and ruminal fermentation variables was studied. Milk yield and herbage dry matter intake (HDMI) was higher for cows that grazed 8 h compared to 4 h, and there were no differences for the time of grazing allocation. However, cows that grazed from 11-15 h (T11-15) spent less time grazing with a greater bite mass and intake rate than cows that grazed from 7-11 h, and could explain the higher milk protein production. Ruminal pH of T11-15 dropped faster than T7-11 cows, which was in line with the higher VFA and ammonia concentrations observed in T11-15. Milk fat concentration and yield were higher in cows that received corn silage divided twice a day than those who received it at one time consistent with the higher HDMI observed. The timing of corn silage supplementation related to grazing session affected ruminal kinetics in terms of pH, ammonium and VFA concentration, and liquid/solid ratio fractions. Corn silage before grazing worked as a buffer for ruminal fermentation, but at the same time as a satiety signal and impact on rumen fill and fermentation due to changes in grazing and ruminating pattern and total DMI. The research strategy allowed us to understand how the grazing dairy cows modify ingestion and digestion on a daily basis, when they are exposed to a limited amount of feeding resources in different setups, showing high plasticity and adaptation on both: ingestion and digestion. A new window of opportunities has been opened after these results, to improve efficiency of the use of feeding resources applying alternative feeding strategies.