Milk production and methane emissions from dairy cows fed silages from different grassland species and harvesting frequencies

The aim of this study was to examine how silages from different grassland species and harvesting frequencies affect feed intake, milk production, and methane (CH4) emission in dairy cows. We hypothesized that cows consuming silages of more frequent harvest, grass species with greater OM digestibility and legumes with lower NDFom concentration would have greater silage DMI and milk yield and thereby lower CH4 yield and intensity. Forty Norwegian Red cows were allocated to 5 treatments in a cyclic changeover design with four 21-d periods (14 d of adaptation, 7 d of data collection). The 5 treatments evaluated were silages produced from timothy (Phleum pratense L.) in a 3-cut system (T3), timothy in a 2-cut system (T2), perennial ryegrass (Lolium perenne L.) in a 3-cut system (PR3), red clover (Trifolium pratense L.) in a 3-cut system (RC3) and a mix of T3 and RC3 (50:50 on DM basis; T3/RC3). The treatments were prepared by mixing silages from each crop over the growing season, proportional to the harvested DM yield of each cut. Cows were offered the mixed silages ad libitum supplemented with a fixed level of concentrate. Gas emissions were measured using 2 Greenfeed units. Milk yield was recorded in the milking robot at each visit, and milk samples were collected at 3 consecutive milkings during the last 7 d of each period. Cows were weighed after each milking, and total-tract digestibility of each diet was estimated using acid insoluble ash as internal marker in fecal grab samples. The data were analyzed using the MIXED procedure of SAS with block, period, and treatment as fixed effects and animal within block as random effect. Silage and total DMI did not differ between T3 and T2, but total DMI was lower for PR3 than for T3. There was a quadratic effect of increased proportion of red clover, with highest intakes of T3/RC3 and lower intakes of RC3 than of T3. Energy-corrected milk yield was lower for T2 than T3, and for PR3 than T3. There was a quadratic effect of increased proportion of red clover, with highest ECM yield in T3/RC3 and lower in RC3 than in T3. Organic matter digestibility was lower for T2 than T3, but it did not differ between T3 and PR3. Including red clover in the diet linearly decreased OM digestibility. Methane production (g/d) did not differ between T3 and T2, but CH4 intensity (g/kg ECM) was greater for T2 than for T3. There was no difference between T3 and PR3 for CH4 production but yield and intensity were greater for PR3 than T3. Including red clover in the diet linearly increased CH4 production, yield and intensity with greatest intensity in the 100% red clover diet. In conclusion, changing harvesting frequency for timothy from 2 to 3 harvests per year did not affect CH4 production or yield, but CH4 intensity was reduced. Replacing timothy with perennial ryegrass and increased inclusion rate of red clover both increased CH4 yield and intensity.

The effect of Phyllanthus emblica (Amla) fruit supplementation on the rumen microbiota and its correlation with rumen fermentation in dairy cows

Introduction

Medicinal plants, rich in phytochemicals like phenolic acids, flavonoids, and tannins, offer potential benefits in enhancing productivity, quality, and animal health. Amla fruit (Phyllanthus emblica) is one such plant with promising attributes. This study aimed to investigate the impact of fresh Amla fruit (FAF) supplementation on ruminal microbial composition and its correlation with rumen fermentation in lactating dairy cows.

Methods

The study employed a repeated crossover design involving eight ruminally cannulated mid-lactation Holstein dairy cows. Animals received varying levels of fresh Amla fruit supplementation (0, 200, 400, and 600 g/d).

Results

When 400 g/d of FAF was added to the diet, there was a significant increase in the relative abundance of Firmicutes (p = 0.02). However, at 200 g/d, the relative abundance of ruminal Bacteroidota was higher than the 0 and 400 g/d FAF supplementation (p < 0.01). LEfSe analysis identified distinct taxa, such as Clostridia vadinBB60 in the 200 g/d group, Oscillospiraceae in the 400 g/d group, and Elusimicrobium in the 600 g/d group. Notably, the random forest species abundance statistics identified Oscillospiraceae V9D2013 as a biomarker related to milk yield. Oscillospiraceae, Bacilli RF39, norank_f Prevotellaceae, and Bifidobacterium were positively correlated with ruminal total VFA and molar proportion of propionate, while Rikenellaceae RC9 gut group and Clostridia vadinBB60 were negatively correlated.

Discussion

FAF supplementation affects the abundance of beneficial microbes in a dose-dependent manner, which can improve milk yield, efficiency, rumen health, desirable fatty acids, and animal health.

Milk from cows fed clover-rich silage compared with cows fed grass silage is higher in n-3 fatty acids

The present study investigated the effect of a high proportion of different forage species in the diet, parity, milking time, and days in milk (DIM) on milk fatty acid (FA) profile, and transfer efficiency of C18:2n-6, C18:3n-3, n-6, and n-3 in dairy cows. Swards with perennial ryegrass [early maturity stage (EPR) and late maturity stage (LPR)], festulolium, tall fescue (TF), red clover (RC), and white clover (WC) were cut in the primary growth, wilted, and ensiled without additives. Thirty-six Danish Holstein cows in an incomplete Latin square design were fed ad libitum with total mixed rations containing a high forage proportion (70% on dry matter basis). The total mixed rations differed only in forage source, which was either 1 of the 6 pure silages or a mixture of LPR silage with either RC or WC silage (50:50 on dry matter basis). Proportion of C18:2n-6 in milk FA was affected by diet, and RC and WC diets resulted in the highest proportion of C18:2n-6 in milk FA (21.6 and 21.8 g/kg of FA, respectively). The highest and lowest milk C18:3n-3 proportion was observed in WC and LPR, respectively. In addition, WC diet resulted in highest transfer efficiency of C18:3n-3 from feed to milk (12.2%) followed by RC diet (10.7%), whereas EPR diet resulted in the lowest transfer efficiency of C18:3n-3 (3.45%). The highest milk proportion of cis-9,trans-11 conjugated linoleic acid (CLA) was observed in cows fed TF (3.20 g/kg of FA), which was 23 to 64% higher than the proportion observed in the cows fed the other diets. The highest α-tocopherol concentration (µg/mL) in milk was observed in EPR (1.15), LPR (1.10), and festulolium (1.06). Primiparous cows showed higher proportion of cis-9,trans-11 CLA (2.63 g/kg of FA) than multiparous cows (2.21 g/kg of FA). Cows early in lactation had a higher proportion of long-chain FA in milk than cows later in lactation, as long-chain FA decreased with 0.184 g/kg of FA per DIM, whereas medium-chain FA increased with 0.181 g/kg of FA per DIM. Proportion of C18:2n-6 in milk from evening milking was higher than in milk from morning milking (16.7 vs. 15.8 g/kg of FA). In conclusion, the results showed that milk FA profile of cows was affected by forage source in the diet, and RC and WC increased the health-promoting FA components, particularly n-3, whereas the TF diet increased proportion of CLA isomers in milk. Proportion of CLA isomers in milk FA from primiparous cows was higher than in milk from multiparous cows. In addition, evening milk contained more FA originating from diets compared with morning milk.

Dairy farming system markers: The correlation of forage and milk fatty acid profiles from organic, pasture and conventional systems in the Netherlands

The relationships between the fatty acid (FA) composition in forage and milk (F&M) from different dairy systems were investigated. Eighty milk samples and 91 forage samples were collected from 40 farms (19 organic, 11 pasture and 10 conventional) in the Netherlands, during winter and summer. The FA profiles of F&M samples were measured with gas chromatography. The results showed that the F&M of organic farms were significantly differentiated from the F&M of other farms, both in summer and winter. The differences are likely due to the different grazing strategies in summer and different forage composition in winter. The Pearson's correlation results showed the specific relationship between individual FAs in forages and related milk. A PLS-DA model was applied to classify all milks samples, resulting in 87.5% and 83.3% correct classifications of training set and validation set.

Red clover silage improves milk fatty acid composition in dairy ewes

The purpose of this study was to evaluate the effects of two isoproteic total mixed rations containing either red clover (Trifolium pratense L.; RC diet) or lucerne (Medicago sativa L.; LU diet) silage as the major forage source on milk yield, milk composition, and milk fatty acid (FA) profile in dairy ewes. Sixteen dairy ewes were housed individually to receive the drawn diet (eight ewes eating each diet) and milked twice a day (0700 and 1500). Total dry matter intake, milk yield, milk composition, and nitrogen use efficiency were unaffected by treatments. The n-6/n-3 FA ratio tended to decrease, whereas the total polyunsaturated fatty acids (PUFAs) and PUFAs/saturated fatty acids ratio increased in the milk fat of ewes fed the RC diet compared with ewes fed the LU diet. The presence of α-linolenic (C18:3n-3) and linoleic (C18:2n-6) acids in the milk fat was 22% higher in ewes fed the RC diet than in those fed the LU diet. Compared with the LU diet, the RC diet had no effect on milk yield and composition, but improved the milk FA profile in dairy ewes due to an increased proportion of PUFAs (in particular C18:3n-3 and, to a lesser extent, C18:2n-6) and a decreased n-6/n-3 FA ratio.

Phenolic content and ferric reducing-antioxidant power of cow's milk produced in different pasture-based production systems in southern Brazil

BACKGROUND

Phenolic compounds are widely present in forage. However, few studies have been carried out to investigate the presence of these compounds in animal products such as milk. In this study, the total phenolic content (TPC) and ferric reducing-antioxidant power (FRAP) of milk produced under agroecological and conventional management systems in southern Brazil were determined. Three systems were compared: (a) agroecological, with intensive rotational grazing, also known as Voisin grazing (ECO); (b) semi-intensive conventional (SIC); and (c) conventional grazing (CGR) (n = 8 per group). Pastures with distinct and more diverse botanical composition were observed on the ECO farms.

RESULTS

Significantly (P < 0.05) lower amounts of TPC were found in agroecologically produced milk in autumn and summer and the CGR system showed the highest FRAP value (P < 0.05) for the samples collected in autumn. Positive correlations where found between the TPC and FRAP values obtained for the milk samples (0.198, P < 0.05), milk FRAP and forage TPC values (0.344, P < 0.05), and the TPC and FRAP values obtained for the forage (0.70, p < 0.01). PCA applied to the UV spectra dataset (200-350 nm) clearly distinguished the samples collected from the ECO system in the winter.

CONCLUSION

Our results revealed that, under the conditions prevalent in southern Brazil, since the cows were allowed to graze in all of the systems, the TPC and antioxidant capacity of the milk samples showed minimal variation. However, since the forage TPC and FRAP values for the milk were correlated, TPC appears to be a promising variable for the purpose of monitoring forage prior to its selection aimed at enhancing the antioxidant activity of milk.

Gastrointestinal metabolism of phytoestrogens in lactating dairy cows fed silages with different botanical composition

Dietary phytoestrogens are metabolized or converted in the gastrointestinal tract of ruminants, only limited knowledge exists on the extent and location of this conversion in vivo. The objective of this study was to quantify the gastro-intestinal metabolism of phytoestrogens in lactating dairy cows fed silages with different botanical composition. Four lactating rumen cannulated Norwegian Red cattle were assigned to a 4 × 4 Latin square with 1 cow per treatment period of 3 wk. The 4 treatment silages were prepared from grasslands with different botanical compositions: organically managed short-term timothy (Phleum pratense L.) and red clover (Trifolium pratense L.) ley (2 yr old: ORG-SG); organically managed long-term grassland with a high proportion of unsown species (6 yr old; ORG-LG); conventionally managed perennial ryegrass (Lolium perenne L.) ley (CON-PR); and conventionally managed timothy ley (CON-TI). The herbages were cut, wilted, and preserved with additive in round bales, fed as a mix of the first and third cut at 90% of ad libitum intake, and contributed to 70% of the total dry matter intake. Milk, feed, omasal digesta, urine, and feces were collected at the end of each period and analyzed for the concentrations of phytoestrogens by using a liquid chromatography-tandem mass spectrometry technique. Concentration of total isoflavones was highest in ORG-SG and lowest in CON-TI silage, whereas the content of total lignans was highest in the grass silages. The isoflavones were extensively metabolized in the rumen on all diets, and the recovery of formononetin and daidzein in omasum, mainly as equol, averaged 0.11 mg/mg. The apparent intestinal metabolism was less severe as, on average, 0.29 mg/mg of the omasal flow was recovered in feces. The plant lignans were also strongly degraded in the rumen. However, the flow of lignans to omasum and excretion in feces were, on average, 7.2- and 5.2-fold higher, respectively, than the intake of the plant lignans matairesinol and secoisolariciresinol, known as precursors of mammalian lignans. Thus, excretion to milk could not be directly related to intake, implying that plant lignans other than matairesinol and secoisolariciresinol in forage are precursors for enterolactone production in the rumen and for its content in milk. Equol followed mainly the flow of large particles out of the rumen, whereas the mammalian lignans were distributed between phases proportional to dry matter flow. The main metabolism of phytoestrogens occurred in the rumen and the main route of excretion was through feces and urine, with only a small part being excreted in milk. The concentration of phytoestrogens in milk can be manipulated through intake but the intermediate transfer capacity to milk appears to be limited by saturation.