Milk Production Responses Research Articles

In vitro and in silico assessment of cytotoxicity of dinitramine via calcium dysregulation and mitochondrial dysfunction in bovine mammary glands

The herbicide market is expanding rapidly due to the global increase in herbicide usage. Dairy cows are susceptible to herbicide exposure through the ingestion of contaminated plants, which can adversely affect the mammary gland health and reduce milk production. Dinitramine, a synthetic herbicide in the dinitroaniline family, is typically used to control weeds by inhibiting their sprouting and root development. While previous studies have demonstrated the cytotoxicity of dinitramine in aquatic organisms, research on its toxicity in cattle is limited. In this study, bovine mammary epithelial cells (MAC-T) were used to verify the detrimental effects on dairy cows, especially on the mammary glands. First, we evaluated the cytotoxic effects of dinitramine on MAC-T cells and examined various cellular responses to dinitramine treatment, including alterations in apoptotic cells, mitochondrial dysfunction, and calcium dysregulation. Moreover, the expression levels of AKT and MAPK signaling proteins were confirmed in response to dinitramine treatment. Alterations in the mRNA levels of genes related to milk production and inflammatory response following dinitramine exposure were evaluated using quantitative PCR. Finally, we assessed the binding affinity between dinitramine and the target proteins using in silico molecular docking analysis. Overall, the cumulative evidence of the various toxic effects of dinitramine on MAC-T cells suggests its potential to reduce both milk yield and quality.

Fecal egg counts and individual milk production in temperate pastoral dairy systems of Australia

Anthelmintic use in lactating dairy cattle, has been shown to result in a milk production response in some previous studies. If individual animals within a herd could be identified that would most benefit from anthelmintic treatment, this may reduce anthelmintic resistance. Australian dairy systems are predominantly pasture-based, allowing sustained exposure and immune stimulation of cattle to gastrointestinal nematodes. We assessed the relationship between milk production and early lactation fecal egg counts (FEC) to determine whether cows with higher FEC produced less milk. Ten pasture-based dairy farms in south-west Victoria, Australia, entered an observational study. Individual FECs at a minimum detectable count of 2.5 eggs per gram of feces (epg) were recorded for recently calved primiparous and multiparous cohorts on each farm. All animals were calved ≤30 d at sampling. Body condition scores were assessed at sampling and milk production data was collected from daily milk meters and herd tests to give first 100-d milk production. When separated by primiparous or multiparous status, no difference in the milk production between cows with FEC = 0 and FEC ≥2.5 epg was identified. Between farm variation was large for FEC and milk production. Fecal egg count at a minimum detectable count of 2.5 epg detected parasitism in primiparous cows post calving but the presence and magnitude of parasitism measurable by FEC was not related to milk production in pasture based Australian dairy systems. In multiparous cows, the rate detection of worm eggs at this analytical sensitivity was lower and the significance of a positive FEC at this analytical sensitivity requires further assessment to ascertain the effect on milk production. Based on our study, it seems unlikely that individual FEC results would be useful as a basis to select individual cows in southwest Victorian dairy herds for anthelmintic treatment.

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

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

Effect of increasing dietary inclusion of whole cottonseed on nutrient digestibility and milk production of high-producing dairy cows

We determined the effects increasing dietary inclusion of whole cottonseed (WCS) on nutrient digestibility and milk production responses of high-producing dairy cows. Twenty-four multiparous Holstein cows (mean ± SD; 52.7 ± 2.63 kg/d of milk; 104 ± 23 DIM) were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design with 21-d periods. Treatments were increasing doses of WCS at 0, 8, 16, and 24% DM, with WCS replacing soybean meal and hulls to maintain similar diet nutrient composition (%DM) of NDF (32%), forage NDF (21%), starch (27%), and CP (17%). Total fatty acid (FA) content of each treatment was 1.70, 2.96, 4.20, and 5.40%DM, respectively. Three preplanned contrasts were used to test the linear, quadratic, and cubic effects of increasing dietary WCS. Increasing dietary WCS from 0 to 24% DM quadratically influenced intakes of DM and NDF, with the highest value being for the 8% WCS, and intakes of 16- and 18-carbon, and total FA, with maximum values obtained up to 24% WCS. Increasing dietary WCS affected digestibility of DM (cubic) and NDF (quadratic), with the lowest values being for the 8% WCS. Increasing WCS increased 16-carbon digestibility (quadratic) but decreased digestibility of 18-carbon and total FA (both quadratic), with highest and lowest values for the 24% WCS, respectively. Increasing dietary WCS quadratically increased absorbed 16- and 18-carbon, and total FA, with maximum values obtained for 24% WCS. Increasing dietary WCS quadratically increased yields of milk, milk fat, milk protein, milk lactose, 3.5% fat corrected milk, and energy corrected milk, and linearly increased body weight gain. The source of milk FA was affected by dietary WCS, with a quadratic decrease in the yield of de novo and mixed milk FA and a quadratic increase in preformed milk FA. Increasing dietary WCS linearly increased trans-10 C18:1 milk FA content. As dietary WCS increased, plasma insulin linearly decreased, and plasma gossypol levels linearly increased. Despite the decrease in total FA digestibility, increasing dietary WCS from 0 to 24% DM increased FA absorption. Increasing dietary inclusion of WCS up to 16% DM increased milk production responses and DM intake. Under the current dietary conditions, high-producing dairy cows benefited best from a diet containing 8-16% DM inclusion of WCS.

Genetic legacy and adaptive signatures: investigating the history, diversity, and selection signatures in Rendena cattle resilient to eighteenth century rinderpest epidemics

BackgroundRendena is a dual-purpose cattle breed, which is primarily found in the Italian Alps and the eastern areas of the Po valley, and recognized for its longevity, fertility, disease resistance and adaptability to steep Alpine pastures. It is categorized as 'vulnerable to extinction' with only 6057 registered animals in 2022, yet no comprehensive analyses of its molecular diversity have been performed to date. The aim of this study was to analyse the origin, genetic diversity, and genomic signatures of selection in Rendena cattle using data from samples collected in 2000 and 2018, and shed light on the breed's evolution and conservation needs.ResultsGenetic analysis revealed that the Rendena breed shares genetic components with various Alpine and Po valley breeds, with a marked genetic proximity to the Original Braunvieh breed, reflecting historical restocking efforts across the region. The breed shows signatures of selection related to both milk and meat production, environmental adaptation and immune response, the latter being possibly the result of multiple rinderpest epidemics that swept across the Alps in the eighteenth century. An analysis of the Rendena cattle population spanning 18 years showed an increase in the mean level of inbreeding over time, which is confirmed by the mean number of runs of homozygosity per individual, which was larger in the 2018 sample.ConclusionsThe Rendena breed, while sharing a common origin with Brown Swiss, has developed distinct traits that enable it to thrive in the Alpine environment and make it highly valued by local farmers. Preserving these adaptive features is essential, not only for maintaining genetic diversity and enhancing the ability of this traditional animal husbandry to adapt to changing environments, but also for guaranteeing the resilience and sustainability of both this livestock system and the livelihoods within the Rendena valley.

Genetic analysis of phenotypic indicators for heat tolerance in crossbred dairy cattle

Climate change-induced rise in global temperatures has intensified heat stress on dairy cattle and is contributing to the generally observed low milk productivity. Selective breeding aimed at enhancing animals’ ability to withstand rising temperatures while maintaining optimal performance is crucial for ensuring future access to dairy products. However, phenotypic indicators of heat tolerance are yet to be effectively factored into the objectives of most selective breeding programs. This study investigated the response of milk production to changing heat load as an indication of heat tolerance and the influence of calving season on this response in multibreed dairy cattle performing in three agroecological zones Kenya. First-parity 7-day average milk yield (65 261 milk records) of 1 739 cows were analyzed. Based on routinely recorded weather data that were accessible online, the Temperature-Humidity Index (THI) was calculated and used as a measure of heat load. THI measurements used represented averages of the same 7-day periods corresponding to each 7-day average milk record. Random regression models, including reaction norm functions, were fitted to derive two resilience indicators: slope of the reaction norm (Slope) and its absolute value (Absolute), reflecting changes in milk yield in response to the varying heat loads (THI 50 and THI 80). The genetic parameters of these indicators were estimated, and their associations with average test-day milk yield were examined. There were no substantial differences in the pattern of milk yield response to heat load between cows calving in dry and wet seasons. Animals with ≤50% Bos taurus genes were the most thermotolerant at extremely high heat load levels. Animals performing in semi-arid environments exhibited the highest heat tolerance capacity. Heritability estimates for these indicators ranged from 0.06 to 0.33 and were mostly significantly different from zero (P < 0.05). Slope at THI 80 had high (0.64–0.71) negative correlations with average daily milk yield, revealing that high-producing cows are more vulnerable to heat stress and vice versa. A high (0.63–0.74) positive correlation was observed between Absolute and average milk yield at THI 80. This implied that low milk-producing cows have a more stable milk production under heat-stress conditions and vice versa. The study demonstrated that the slope of the reaction norms and its absolute value can effectively measure the resilience of crossbred dairy cattle to varying heat load conditions. The implications of these findings are valuable in improving the heat tolerance of livestock species through genetic selection.

Variation in individual milk production responses to supplementary protein feeding with two types of forages

The objectives of the present experiment were to investigate the effects of forage type and protein supplementation on feed intake and milk production, and between-cow variability in responses to protein supplementation. The experiment was conducted using 40 cows (28 Holstein, 12 Nordic Red, 25 multiparous, 15 primiparous). Experiment started with a covariate period of 14 d when cows received TMR (concentrate:forage, 40:60). After the covariate period four experimental diets were arranged in 2 × 2 factorial design with two forages and two concentrate CP levels. The forage treatment included grass silage (GS) and a mixture of whole-crop wheat/oats silage and grass silage (MIX; 40:60) on DM basis. The concentrate treatment included two concentrate CP levels [low CP (115 g CP/kg DM) and medium CP (166 g CP/kg DM)]. Concentrate CP concentration was increased by replacing barley and oats with rapeseed meal. The cows were fed the same forage throughout the 63-d experiment, whereas the CP treatments were compared in a switch-back design including three 21 d periods. Individual protein supplementation response was calculated based on switch-back periods. Feeding the MIX forage increased total DM intake by 1.3 kg/d compared with the GS diets but milk production was not influenced by forage type. Dry matter and nutrient intake increased with CP level similarly with forages. The production of milk components and milk urea concentration increased with CP level, whereas milk N efficiency decreased. Energy corrected milk (ECM) yield response to protein supplementation was not related to ECM yield measured during the covariate period whereas the ECM response was negatively related to calculated energy balance during covariate period. It is concluded that intake and production responses to moderate level of protein supplementation were highly variable, but the extent of variation could not be predicted from animal characteristics available in farm conditions. When the supply of metabolizable protein (MP) was simulated by the Karoline model for each animal, predicted MP concentration increased 0.8 g/kg increase in DM intake. This is compatible to increased MP requirement on DM basis with enhanced production level. Both the lack of the effects of initial production level on CP response and the higher predicted MP concentration with increased intake suggest that high yielding cows can deal with the higher MP requirement (on DM basis) without increasing dietary CP concentration.

Grounding the economic selection index for evaluation and selection of dairy cattle

The aim of the research was to develop a selection index for the evaluation and selection of dairy cattle for increasing milk production and reproductive traits. Materials of the research were data on milk production and reproduction of cows of the Ukrainian Black-and-White dairy breed in commercial farm in Kharkiv region. Studies showed that there was a certain antagonism between milk productivity and reproduction of the Ukrainian Black-and-White dairy cow. The coefficients of phenotypic correlation between milk yield, fat and protein yield and the days open ranged from +0.284 to +0.293. Selection indexes were built, which included protein, fat yield, and days open. The developed selection indexes were characterized by a high relationship with the protein yield (α&lt;0.001), much lower – with the fat yield (α&lt;0.05), while the relationship of the selection indexes with the days open was almost absent. The calculated estimates of correlation and regression coefficients made possible to predict correlated responses of milk production and reproduction traits on selection index. The results showed that the developed selection indexes allow increase the milk production of cows and at the same time to prevent decrease in the level of reproduction.

Milk production responses of dairy cows to fatty acid supplements with different ratios of palmitic and oleic acids in low- and high-fat basal diets

We evaluated the effects of fatty acid (FA) supplements with different ratios of palmitic acid (C16:0) and oleic acid (cis-9 C18:1) in low- and high-FA basal diets on production responses of lactating dairy cows. Thirty-six multiparous Holstein cows (50.2 ± 5.8 kg/d of milk; 160 ± 36 d in milk) were used in a split-plot Latin square design balanced for carryover effects. Cows were blocked by milk yield and allocated to a main plot receiving either a low-FA (LF; 1.93% FA content) basal diet (n = 18) containing cottonseed meal and cottonseed hulls or a high-FA (HF; 3.15% FA content) basal diet (n = 18) containing whole cottonseed. Within each plot, a 3 × 3 Latin square arrangement of treatments was used in 3 consecutive 21-d periods. Treatments were (1) control (CON; no FA supplementation), (2) FA supplement containing 80% C16:0 + 10% C18:1 (PA), and (3) FA supplement containing 60% C16:0 + 30% cis-9 C18:1 (PA+OA). The FA supplements were fed at 1.5% of dry matter and replaced soyhulls in CON. Preplanned contrasts were (1) overall effect of FA supplementation {CON vs. the average of the FA treatments [1/2 (PA + PA+OA)]}, and (2) the effect of the PA treatment versus the PA+OA treatment (PA vs. PA+OA). Treatment by basal diet interactions were observed for yields of milk and lactose, where FA treatments increased yields of milk and milk lactose in LF but not in HF. Basal diet had no effect on dry matter intake (DMI) or milk yield. Compared with LF, HF increased milk fat yield and 3.5% fat-corrected milk (FCM) and tended to increase milk fat content and energy-corrected milk (ECM) yield. The FA treatments decreased DMI but increased the yields of milk fat, 3.5% FCM, and ECM, compared with CON, due to increases in mixed and preformed milk FA yields. The PA+OA treatment decreased DMI and milk protein yield compared with PA. In conclusion, a high-fat basal diet increased milk fat production, and the addition of FA supplements to a low-fat basal diet increased milk lactose yield and tended to increase milk yield. Additionally, regardless of basal diet fat level, FA supplements increased production responses compared with the non-FA-supplemented control diet.

Increasing palmitic acid and reducing stearic acid content of supplemental fatty acid blends improves production performance of mid-lactation dairy cows

We determined the effects of altering the ratio of palmitic (C16:0) and stearic (C18:0) acids in supplemental fatty acid (FA) blends on production responses of mid-lactation dairy cows. Twenty-four multiparous Holstein cows (mean ± standard deviation; 47.1 ± 5.8 kg of milk yield, 109 ± 23 DIM) were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design with 21-d periods. Treatments were a control diet not supplemented with FA (CON), and 3 diets incorporating 1.5% of dry matter (DM) FA supplement blends containing 30% C16:0 + 50% C18:0, 50% C16:0 + 30% C18:0, and 80% C16:0 + 10% C18:0. Additionally, the FA blends were balanced to contain 10% of oleic acid (cis-9 C18:1). The FA blends replaced soyhulls in the CON diet. Diets were formulated to contain (% of DM) 31.0% neutral detergent fiber, 27.0% starch, and 16.9% crude protein. The statistical model included the random effect of cow within square and the fixed effects of period, treatment, and their interaction. Preplanned contrasts included CON versus overall effect of FA supplementation and the linear and quadratic effects of increasing C16:0 in FA blends. Overall FA treatment had no effect on dry matter intake (DMI), but increasing C16:0 linearly increased DMI. Compared with CON, overall FA treatment increased yields of milk, 3.5% of fat-corrected milk, energy-corrected milk, and milk fat but did not affect milk protein yield. Increasing C16:0 linearly increased milk fat yield and tended to linearly increase the yields of 3.5% of fat-corrected milk and energy-corrected milk. Fatty acid supplementation decreased the yield of de novo milk FA but increased yields of mixed and preformed milk FA compared with CON. Increasing C16:0 in FA treatments did not affect the yield of de novo milk FA, linearly increased the yield of mixed, and decreased the yield of preformed milk FA. In summary, feeding FA supplements containing C16:0 and C18:0 increased milk production responses with no effect on DMI compared with a control diet. Mid-lactation cows producing ∼40 to 50 kg/d milk yield responded best to increasing supplemental C16:0 in FA supplements, demonstrating that FA supplements higher in C16:0 and limited in C18:0 improves production responses.

Replacing silage with large amounts of concentrate and straw affects milk production, economics and climate differently in Holstein and Jersey Cows

With droughts becoming more frequent due to climate changes alternative feeding strategies are required. The aim of this study was to examine the effects of replacing all or part of the silage component with barley straw and concentrates for Holstein and Jersey cows. Forty-nine Holstein and 43 Jersey cows were fed either the C49 diet (Roughage-to-concentrate ratio [% of DM; dry matter] of 51:49), a diet where concentrate constituted 70% of DM (i.e., diet C70; 30:70), or the extreme diet (i.e., C91; 9:91), where 91% of DM was concentrate and 9% of DM was barley straw. Cows were allowed up to 2.65 kg DM per day from concentrate in the automatic milking system (AMS). Cows were fed their diets for 5 weeks. All diets were formulated to provide the same daily net energy intake. Daily feed intake and milk production responses were recorded. Volatile fatty acid profiles in rumen fluid were measured for Holstein cows. Impact on economy and carbon footprint were calculated. Data were analyzed using a general linear mixed model. For both breeds, total dry matter intake (i.e., AMS concentrate + partially mixed ration) decreased with increasing concentrate proportion. In neither Holstein nor Jersey, experimental diet affected milk yield. A decrease in fat percentage and ECM was observed for both breeds, when the level of concentrate was increased. However, there was an interaction between diet and breed for fat percentage and for energy-corrected milk yield (ECM), and there was an interaction for feed efficiency expressed as kg of ECM/kg of DM intake. For Holstein cows, acetate molar proportion in rumen liquid decreased and propionate molar proportion increased when silage was reduced. Regardless of breed, increasing concentrate in the ration did not affect carbon footprint per kg ECM, but caused a decrease per cow per day, and per kg DM intake. However, if the contribution from direct land use changes and soil C were taken into account, increasing concentrate in the ration reduced carbon footprint per kg ECM due to decreased proportion of soybean meal in C75 and C91 diets. Production of milk from predominantly concentrate based diets containing no grass silage reduced income over feed cost for both breeds but more for Holsteins. In conclusion, results showed that it is possible to keep dairy herds and produce milk even during extreme drought, when availability of silage is minimal, whereas such ration decreased income over feed cost.

Effects of corn silage supplementation strategy and grazing intensity on herbage intake, milk production, and behavior of dairy cows

Effects of corn silage supplementation on milk production of grazing dairy cows depend in part on the substitution rate between the 2 forages, which may be influenced by grazing management. The aim of this study was to compare 2 grazing management strategies for measuring substitution rate between herbage and corn silage, in interaction with grazing intensity. Six treatments were compared, with 2 grazing intensities and 3 supplementation strategies investigated at both grazing intensities. The 2 grazing intensities were severe and light grazing, defined by either (1) herbage allowance (HA) of 15 (severe) or 30 (light) kg dry matter (DM)/cow per d at 3 cm above ground level or (2) postgrazing sward height, depending on the supplementation strategy. The 3 supplementation strategies were as follows: (U) an unsupplemented treatment, (A) 5 kg DM/d of corn silage offered at a similar HA as in U, and (H) 5 kg DM/d of corn silage offered at a similar postgrazing sward height as in U. Thirty-six multiparous Holstein cows were used in a randomized complete block design and divided in 2 groups for the entire experiment, one for each grazing intensity. Within each grazing intensity group, the corn silage supplementation strategy was studied using a 3 × 3 Greco-Latin square design, with 3 periods of 14 d. Supplementing cows with corn silage increased total DM intake only for severe grazing by 1.7 kg DM/d. The substitution rate between corn silage and grazed herbage was lower for severe than for light grazing, averaging 0.63 and 1.23, respectively. Herbage dry matter intake was lower by 1.2 kg/d for strategy H than A, leading to lower substitution rates (0.81 vs. 0.99, respectively), irrespective of grazing intensity. Milk production increased with silage supplementation for severe grazing (+1.0 kg/d milk) and was unaffected by silage supplementation for light grazing (-0.4 kg/d milk). The milk production response to corn silage supplementation averaged +0.23 and -0.08 kg of milk per kg DM of silage for severe and light grazing, respectively. Fat-corrected milk production tended to be lower by 0.4 kg/d for strategy H than A, leading to lower milk production response (+0.00 vs. +0.12 kg of milk per kg DM of silage, respectively). Milk protein concentration increased with silage supplementation for severe grazing (+1.0 g/kg) but decreased with silage supplementation for light grazing (-0.6 g/kg). Milk fat concentration did not differ among treatments. On average, daily grazing time (-47 min/d, i.e., -9%) and herbage intake rate (-4.9 g of DM/min, i.e., -14%) decreased when cows were supplemented, with greater grazing time reduction at severe than light grazing, and greater herbage intake rate reduction at light than severe grazing. In conclusion, the greater substitution rate and the lower 4% fat-corrected milk production when corn silage was provided at a similar postgrazing sward height rather than at a similar HA to those of unsupplemented cows explain why supplementing grazing dairy cows with conserved forages has no strong effect in practice from a production point of view.

The effect of grass silage harvesting strategy and concentrate level on feed intake, diet digestibility and milk production of dairy cows

Two experiments were conducted under Northern European conditions to quantify dairy cow responses to variable grass silage quality and concentrate feed supplementation. Experiment 1 included 3 primary growth grass silages (early, intermediate and late maturity stage) supplemented with three concentrate levels (9, 12 and 15 kg d-1). Experiment 2 included three consecutive harvests (first, second and third harvest from the same sward within the growing season) and three levels of concentrate supplementation (9, 11 and 13 kg d-1). Dairy cows responded clearly to changes in the harvesting time of silage in primary growth (quadratic effect) and amount of concentrate (linear effect) in the diet in Experiment 1. Milk yield was the lowest with third harvest silage in Experiment 2, and responses to increasing concentrate allowance were linear. Interactions between silage quality and concentrate supplementation were detected in Experiment 1, where milk production responses to additional concentrate decreased with increasing silage digestibility. No interactions were found in Experiment 2, probably due to the small range of differences in nutritional quality between the silages prepared from different harvests. The results demonstrated that it is difficult to compensate for low silage digestibility by increasing the amount of concentrate. The variable ECM response (from –0.01 to 0.85 kg ECM per kg DM incremental concentrate in the diet) is explained by the concomitant decrease in silage intake and negative effect on diet neutral detergent fibre digestibility.

The Replacement of Ground Corn with Sugar Beet in the Diet of Pasture-Fed Lactating Dairy Cows and Its Effect on Productive Performance and Rumen Metabolism.

Simple SummaryCereal grains have increased in cost, and therefore dairy farmers try to find alternatives to provide energy in the rumen. Sugar beet roots have high energy content and may be a sound alternative to replace ground corn partially or totally in the diet of dairy cows. Thus, the aim of this study was to evaluate the replacement of ground corn with fresh sugar beet on the milk production responses, rumen metabolism, and profitability of pasture fed dairy cows. Although cows supplemented with sugar beet roots had reduced dry matter intake and milk production compared with control cows, fat percentage was increased, and therefore, there were no differences in energy corrected milk yield (FPCM) among the treatments. Moreover, feeding costs were reduced, and thus, the margin over feed costs was increased for sugar beets. In addition, the replacement of ground corn by sugar beets reduced urinary N excretion, and thus, it may contribute to the reduction in N2O emission from dairy systems. Using sugar beet roots as an energy supplement can be a suitable alternative to ground corn in pasture-fed lactating dairy cows, increasing the sustainability of dairy systems.(1) Background: Sugars have a potential to provide great amounts of fermentable energy in the rumen. Feeding fresh sugar beet (SB) to dairy cattle to replace a portion of the grain in the ration has not received sufficient attention. This study determined dry matter intake (DMI), feeding behavior, rumen fermentation and milk production responses when replacing corn grain with increasing levels of SB in pasture-fed lactating dairy cow diets. (2) Methods: A total of 12 early-lactation cows were used in a replicated (n = 4) 3 × 3 Latin square design. The control diet consisted of 21 kg dry matter (DM) composed of 6.3 kg DM green chopped perennial ryegrass, 7 kg DM grass silage, 2 kg DM of concentrate, 1 kg DM soybean meal and 4.5 kg DM of ground corn. The other treatments replaced 50% or 100% of the ground corn with SB roots. (3) Results: The replacement of ground corn with sugar beet reduced DMI and milk yield (p < 0.05), but it increased milk fat concentration (p = 0.045), reduced feeding costs and increased margin over feed costs (p < 0.01). Urinary nitrogen was linearly reduced with SB supplementation (p = 0.026). (4) Conclusions: Using SB roots as energetic supplement can be a suitable alternative to ground corn in pasture-fed lactating dairy cows.

Metabolic profile and productivity of dairy Holstein cows milked by a pasture-based automatic milking system during early lactation: Effects of cow temperament and parity

This study aimed to evaluate the influence of temperament and parity on milk production and metabolic responses of Holstein cows in a pasture-based automatic milking system. Thirty-five primiparous and 58 multiparous cows were classified as ‘calm’, ‘intermediate’ or ‘reactive’ in each of the temperament tests conducted: milking reactivity (MR), race time (RT), flight speed, and flight distance. The milk yield and milk composition, as well as the blood biochemistry, were measured during the first 10 weeks of lactation. Primiparous cows produced less milk than multiparous cows (24.0 ± 0.8 vs. 34.2 ± 0.6 L/d, respectively, P ˂ 0.0001), while the serum beta-hydroxybutyrate concentration differences according to parity were not detected. Multiparous cows that were classified as ‘reactive’ on MR and RT tests produced 3 kg/d more milk and had greater concentrations of milk components than ‘calm’ cows (P ≤ 0.05). There was no such relation in primiparous cows. Also, cows scored ‘reactive’ on RT showed greater milking frequency (2.50 ± 0.05 vs. 2.35 ± 0.04 milking/d; P = 0.01) and blood beta-hydroxybutyrate concentrations (1.28 ± 0.09 vs. 0.92 ± 0.10 mmol/L; P = 0.04) than RT ‘calm’ cows. In conclusion, the cows' temperament was associated with milk production and metabolism, which depended on parity and the temperament tests used. Although productive performance was different between parities, lipomobilization was not.

Milk production potential of whole crop faba bean silage compared with grass silage and rapeseed meal

The objective of the present study was to compare the effect of whole crop faba bean silage with grass silage as forages for lactating dairy cows. The experiment also allowed comparison of the milk production response of faba bean crude protein (CP) to that derived from a rapeseed meal supplement. Three experimental diets were used: (1) Grass silage supplemented with a cereal-based concentrate (CON), (2) 75% of grass silage replaced on dry matter (DM) basis with whole crop faba bean silage supplemented with a cereal-based concentrate (FB) and (3) Grass silage supplemented with a cereal and rapeseed meal-based concentrate (RSM) so that it was isonitrogenous with FB. The diets were fed as total mixed rations and the target proportion of concentrate in total diet DM was 400 g/kg. The experimental design was a nine times replicated 3 × 3 Latin square and 27 dairy cows were recruited into the experiment. Diet DM intake was significantly greater (P < 0.05) with FB and RSM compared with CON, which was reflected in lower (P < 0.05) milk, energy corrected milk and milk protein outputs of cows on CON than those on FB and RSM. There were no significant differences in milk and protein yields between FB and RSM but energy corrected milk and milk fat yields were greater on RSM (P < 0.05). Milk urea content was lowest in CON and highest on FB while RSM was intermediate (P < 0.05). Whole crop faba bean silage provides a viable option for feed production of dairy farms under Northern European climatic conditions with positive influence on e.g., biodiversity and flexibility in harvesting schedules. In spite of the moderate energy value of faba bean silage, it has a good feed intake potential, and when replacing grass silage in the diet, can be assumed to maintain or even increase milk yield. The higher supply of CP from FB compared to that of grass silage is however not as valuable as that originating from rapeseed meal, and decreasing nitrogen use efficiency seems inevitable irrespective of the source of additional CP content in the diet of dairy cows.

Effects of high fiber energy supplements on production performance, milk composition and milk fatty acid profile from dairy ewes fed fresh cut Lolium multiflorum

Supplementation of dairy ewes under grazing systems can improve milk production but different responses can be obtained when using starch or high degradable fiber as energy sources. The aim of this study was to evaluate the effect of two contrasting sources of dietary energy on animal production, milk composition and fatty acid (FA) profile of dairy ewes fed fresh ryegrass. Ten Pampinta ewes (28 ± 2.3 DIM; 65.8 ± 8.67 kg BW) were assigned to one of two dietary treatments in a complete randomized design with repeated measures: SH (soybean hulls) and CG (corn grain). Daily ration consisted of fresh ryegrass (Lolium multiflorum) plus concentrate in a 50:50 ratio (4% of BW). The experiment lasted 5 weeks, with 3 weeks for data collection. Individual milk samples were analyzed for milk composition and milk FA profile. Data were analyzed in a complete randomized design where supplement was considered a fix effect and ewe the random effect. Dry matter and forage intake were higher in SH (P < 0.05). Milk yield, milk protein and milk fat were similar between treatments. Compared to CG, total polyunsaturated FA (6.77 vs. 4.49 g/100g FA), total n-3 FA (0.89 vs. 0.58 g/100g FA) and total n-6 FA (3.43 vs. 1.94 g/100g FA) were higher in milk from SH (P < 0.05). Results suggest that replacing starch with fibrous supplements in early-lactation dairy ewes constitutes a promising alternative to obtain a more health-promoting FA profile in milk, without compromising milk yield and composition.

Dietary Fat and Betaine Supplements Offered to Lactating Cows Affect Dry Matter Intake, Milk Production and Body Temperature Responses to an Acute Heat Challenge.

Simple SummaryHot weather is associated with reduced milk yield of dairy cows. Supplementing the diet of lactating cows with ingredients that increase dietary energy density or that reduce internal heat production, may reduce some of the negative impacts of hot weather on milk yield. We used controlled-climate chambers to simulate a short hot-weather event and measured changes in milk yield, feed intake, and body temperature of cows fed either a fat supplement, betaine or a combination of both. Feeding cows fat resulted in improved milk production but also increased body temperature and caused a decrease in feed intake. Feeding betaine did not affect milk yield but did reduce cow body temperature at times. Contrary to our expectations, the combination of fat and betaine supplements did not result in a clear benefit in terms of milk production or body temperature. Further work is warranted to understand the interactions between dietary fat type and betaine supplements when offered to cows during periods of hot weather.Supplementing the diet of lactating cows with ingredients that increase energy density, or reduce internal heat production, may reduce some of the negative impacts of hot weather on milk yield. Thirty-two dairy cows were assigned either: (1) basal diet only, (2) basal diet plus canola oil, (3) basal diet plus betaine, or (4) basal diet plus canola oil and betaine. The basal diet was lucerne hay, pasture silage, and grain. Cows were exposed to a four-day heat challenge (temperature-humidity index 74 to 84) in controlled-environment chambers. Canola oil supplementation increased milk production (22.0 vs. 18.7 kg/d) across all periods of our experiment and increased body temperature (39.6 vs. 39.0 °C) during the heat challenge. Betaine supplementation reduced maximum body temperature during the pre-challenge period (39.2 vs. 39.6 °C) but not during the heat challenge (40.3 °C). Cows fed canola oil had greater declines in dry matter intake (5.4 vs 2.7 kg DM) and energy corrected milk (1.3 vs. 1.0 kg) from the pre-challenge to the heat challenge than other cows. Contrary to our expectations, the combination of fat and betaine supplements did not result in a clear benefit in terms of milk production or body temperature. Further work is warranted to understand the interactions between diet and hot weather.

Milk Production Responses and Digestibility of Dairy Buffaloes (Bubalus bubalis) Partially Supplemented with Forage Rape (Brassica napus) Silage Replacing Corn Silage.

Simple SummaryTo develop alternative silage resources, we employed buffaloes as an animal model to evaluate the possibility and effects of forage rape silage in the dairy buffalo diet. We comprehensively assessed the nutrition value of forage rape silage by the apparent total-tract digestibility, rumen fermentation characteristics, blood metabolism and milk composition of lactating buffaloes. Our current results showed that the inclusion of forage rape silage in diets improved the milk quality, such as milk protein, milk fat, and total solid percentage. Furthermore, partial supplementation of forage rape silage also promotes buffaloes’ dry matter intake. These may be related to the favorable physiological and metabolic changes induced by the forage rape silage. Thus, our current data show the applicability of forage rape silage as a good feed resource for ruminants.Worldwide, silage is considered the main component in dairy animal diets; however, this portion is mainly dominated by corn silage, which raises availability challenges in some agricultural production systems. The present study evaluated a partial replacement of corn silage with forage rape silage (FRS) and its effect on feed intake, nutrient digestibility, rumen fermentation, milk production, and blood metabolites in buffalo. Thirty-six lactating buffaloes were randomly assigned to four different groups, according to supplementation of FRS (only corn silage, FRS0) or with 15% (FRS15), 25% (FRS25), and 35% (FRS35) of forage rape silage instead of corn silage. The results showed that, compared to corn silage, forage rape silage has a lower carbohydrate but a higher protein concentration. The buffalo intake of dry matter and organic matter were improved linearly with the FRS increasing in the diet. The apparent total-tract digestibility (ATTD) of dry matter, organic matter, nitrogen, neutral detergent fiber, and acid detergent fiber also increased by the FRS supplementation compared with FRS0. Conversely, FRS supplementation decreased the propionic, butyric, and valeric acid contents and increased the acetic:propionic ratio and microbial protein content. Furthermore, FRS inclusion led to a significantly higher milk urea and non-fat milk solid content, higher blood glucose, total globulins, blood urea nitrogen, and lower blood high-density lipoprotein. These results suggested that FRS has high a nutritional value and digestibility, is a good feed resource, and showed favorable effects when supplemented with dairy buffalo ration.

Comprehensive Proteomic Analysis Revealed a Large Number of Newly Identified Proteins in the Small Extracellular Vesicles of Milk from Late-Stage Lactating Cows.

Simple SummaryBovine milk provides excellent nutrition for infants and contains significant bioactive compounds, including small extracellular vesicles. Small extracellular vesicles are nanosized particles that have long been recognized to carry a variety of cargos, including proteins, nucleic acids, lipids, and other biomolecules. Previous research has shown that the proteomic profile in milk small extracellular vesicles differed in accordance with the lactation stages of cows, such as early- and mid-stage lactation. However, the protein profile in milk small extracellular vesicles from late-stage lactation is mostly unknown. In this study, a comprehensive proteomic analysis was performed to explore the proteins in milk small extracellular vesicles from late-stage lactating cows. The present study identified a total of 2225 proteins in milk small extracellular vesicles from late-stage lactating cows. Notably, a total of 429 proteins were newly identified after comparing with the previously published bovine milk small extracellular vesicles proteomic datasets. These findings indicate that the newly identified proteins could be helpful in better understanding the proteomic dynamics in milk small extracellular vesicles during the late-stage lactating cows.Bovine milk contains small extracellular vesicles (sEVs) that provide proteins, miRNAs, mRNAs, DNAs, and lipids to target cells and play a role in intracellular communications. Previous studies have characterized proteins in milk sEVs from early- and mid-stage lactation. However, the proteins in milk sEVs from late-stage lactation are mostly unexplored. The aim of this study was to determine the proteomic profile of milk sEVs from late-stage lactating cows. A comprehensive nanoliquid chromatography–tandem mass spectrometry (nanoLC-MS/MS) approach was carried out to reveal the proteins in milk sEVs. Additionally, bioinformatics analysis was carried out to interpret the molecular signatures of newly identified proteins in milk sEVs from three late-stage lactating cows. NanoLC-MS/MS analysis revealed a total of 2225 proteins in milk sEVs from cows. Notably, after comparing these identified proteins with previously deposited datasets of proteins in bovine milk sEVs, 429 proteins were detected as newly identified. Bioinformatic analysis indicated that these newly identified proteins in milk sEVs were engaged in a diverse range of molecular phenomena relevant to mammary gland physiology, milk production, immunity, and immune response. These findings suggest that the newly identified proteins could expand the inventory application of molecular cargos, nutritional status, and immune modulation of sEVs in milk during the late-stage lactation.