Milk production responses and rumen fermentation of dairy cows supplemented with summer brassicas

Gastrointestinal Biogeography of Luminal Microbiota and Short-Chain Fatty Acids in Sika Deer (Cervus nippon)

The gut microbiota of sika deer has been widely investigated, but the spatial distribution of symbiotic microbes among physical niches in the gastrointestinal tract remains to be established. While feces are the most commonly used biological samples in these studies, the accuracy of fecal matter as a proxy of the microbiome at other gastrointestinal sites is as yet unknown. In the present study, luminal contents obtained along the longitudinal axis of deer gastrointestinal tract (rumen, reticulum, omasum, abomasum, small intestine, cecum, colon, and rectum) were subjected to 16S rRNA gene sequencing for profiling of the microbial composition, and samples from the rumen, small intestine, and cecum were subjected to metabolomic analysis to evaluate short-chain fatty acid (SCFA) profiles. Prevotella bacteria were the dominant gastric core microbes, while Christensenellaceae_R-7_group was predominantly observed in the intestine. While the eight gastrointestinal sites displayed variations in microbial diversity, abundance, and function, they could be clustered into stomach, small intestine, and large intestine segments, and the results further highlighted a specific microbial niche of the small intestine. SCFA levels in the rumen, small intestine, and cecum were significantly different, with Bacteroidetes and Spirochaetes were shown to play a critical role in SCFA production. Finally, the rectal microbial composition was significantly correlated with colonic and cecum communities but not those of the small intestine and four gastric sites. Quantification of the compositions and biogeographic relationships between gut microbes and SCFAs in sika deer should provide valuable insights into the interactions contributing to microbial functions and metabolites. IMPORTANCE Feces or specific segments of the gastrointestinal tract (in particular, the rumen) were sampled to explore the gut microbiome. The gastrointestinal biogeography of the luminal microbiota in ruminants, which is critical to guide accurate sampling for different purposes, is poorly understood at present. The microbial community of the rectal sample (as a proxy of fecal sample) showed higher correlation with those of other large intestinal sites relative to the small intestine or stomach, suggesting that the microbial composition is specifically shaped by the unique physiological characteristics of different gastrointestinal niches. In addition, significant differences in microbiomes and SCFAs were observed among the different gastrointestinal sites.

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

(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.

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

Simple Summary

To 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.

Abstract

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.

Effect of dietary inclusion of winter brassica crops on milk production, feeding behavior, rumen fermentation, and plasma fatty acid profile in dairy cows

This study determined feeding behavior, dry matter (DM) intake (DMI), rumen fermentation, and milk production responses of lactating dairy cows fed with kale (Brassica oleracea) or swede (Brassica napus ssp. napobrassica). Twelve multiparous lactating dairy cows (560 ± 22 kg of body weight, 30 ± 4 kg of milk/d, and 60 ± 11 d in milk at the beginning of the experiment; mean ± standard deviation) were randomly allocated to 3 dietary treatments in a replicated 3 × 3 Latin square design. The control diet comprised 10 kg of grass silage DM/d, 4 kg of ryegrass herbage DM/d, and 8.8 kg of concentrate DM/d. Then, 25% of herbage, silage, and concentrate (DM basis) was replaced with either kale or swede. Cows offered kale had decreased total DMI compared with cows fed the control and swede diets, whereas inclusion of swede increased eating time. Milk production, composition, and energy-corrected milk:DMI ratio were not affected. Cows fed with kale had a greater rumen acetate:propionate ratio, whereas swede inclusion increased the relative percentage of butyrate. Estimated microbial N was not affected by dietary treatments, but N excretion was reduced with inclusion of kale, improving N utilization. Cows fed kale tended to have increased nonesterified fatty acids and showed presence of Heinz-Ehrlich bodies, whereas hepatic enzymes such as aspartate aminotransferase, γ-glutamyl transferase, and glutamate dehydrogenase were not affected by dietary treatments. In plasma, compared with the control, swede and kale reduced total saturated fatty acids and increased total polyunsaturated fatty acids and total n-3 fatty acids. Overall, feeding cows with winter brassicas had no negative effect on production responses. However, mechanisms to maintain milk production were different. Inclusion of swede increased the time spent eating and maintained DMI with a greater relative rumen percentage of butyrate and propionate, whereas kale reduced DMI but increased triacylglycerides mobilization, which can negatively affect reproductive performance. Thus, the inclusion of swede may be more suitable for feeding early-lactating dairy cows during winter.

Use of the Comprehensive Climate Index to estimate heat stress response of grazing dairy cows in a temperate climate region

The aim of the study was to assess the effect of the summer thermal environment on physiological responses, behaviour, milk production and its composition on grazing dairy cows in a temperate climate region, according to the stage of lactation. Twenty-nine Holstein Friesian multiparous cows were randomly selected and divided into two groups, according to the days in milk, as mid-lactation (99 to 170 d in milk, n = 15) and late lactation (225 to 311 d in milk, n = 14). The comprehensive climate index (CCI) was used to classify the hour of each day as thermoneutral or heat stress, considering a threshold value of CCI of 20°C. Data were collected for 16 d (summer 2017) and analysed as a completely randomized 2 × 2 factorial arrangement with repeated measurements over time. Vaginal temperature increased with CCI ≥ 20°C. Respiration rates were dependent on the thermal condition, regardless of days in milk. There was an interaction between the time of day and the CCI category for activity and rumination. Grazing activity decreased by 17.6% but lying down, standing, and shaded animals increased by 1.6, 9.8, and 6.3% respectively when CCI ≥ 20°C. Over 80% of cows presented a panting score ≥1. However, milk production and composition (fat, protein, and lactose concentrations as well as somatic cell count) were not affected by the thermal condition, although there was a numerical (non-significant) decrease in afternoon milk protein concentration on days with CCI ≥ 20°C, while urea in milk increased. In conclusion, thermal condition challenged grazing dairy cows' behaviour and physiology independent of the stage of lactation but had little or no effect on milk production.

Chemical Composition, Fatty Acid Profile and Sensory Characteristics of Chanco-Style Cheese from Early Lactation Dairy Cows Fed Winter Brassica Crops

Simple Summary

Brassica crops such as kales and swedes can be supplied to cow diets during winter. Little is known about the effects of feeding those forage brassicas to lactating cows on cheese nutritional characteristics. Thus, the objective of this study was to determine the effect of including kale or swedes in the diet of pasture-fed lactating dairy cows on chemical composition, fatty acid (FA) profile and sensory characteristics of Chanco-style cheese. Kale or swedes can be used in the diet of pasture-fed lactating dairy cows without negative effects on milk production, milk composition and cheese composition. However, with regard to cheese FA profiles, those elaborated from milks from kale and swedes increased total contents of saturated fatty acids.

Abstract

Brassica crops such as kale and swede can be supplied to cow diets during winter, however little is known about the effects of feeding those forage brassicas to lactating cows on cheese nutritional characteristics of milk and cheese. This study evaluated the effect of including kale or swede in pasture-fed lactating dairy cow diets on chemical composition, fatty acid (FA) profile, and sensory characteristics of Chanco-style cheese. Twelve early-lactation cows were used in a replicated (n = 4) 3 × 3 square Latin square design. The control diet consisted of (DM basis) 10.0 kg of grass silage, 4.0 kg of fresh grass pasture, 1.5 kg soybean meal, 1.0 kg of canola meal, and 4.0 kg of cereal-based concentrate. The other treatments replaced 25% of the diet with swede or kale. Milk yield, milkfat, and milk protein were similar between treatments as were cheese moisture, fat, and protein. Swede and kale increased total saturated cheese FA while thrombogenic index was greater in swede, but color homogeneity and salty flavor were greater while ripe cheese aroma less than for kale. Kale or swede can be used in the diet of pasture-fed lactating dairy cows without negative effects on milk production, milk composition, or cheese composition. However, kale and swede increased total cheese saturated FA.

Invited Review: Glucosinolates Might Result in Low Methane Emissions From Ruminants Fed Brassica Forages

Methane is formed from the microbial degradation of feeds in the digestive tract in ruminants. Methane emissions from ruminants not only result in a loss of feed energy but also contribute to global warming. Previous studies showed that brassica forages, such as forage rape, lead to less methane emitted per unit of dry matter intake than grass-based forages. Differences in rumen pH are proposed to partly explain these low emissions. Rumen microbial community differences are also observed, but the causes of these are unknown, although altered digesta flow has been proposed. This paper proposes a new mechanism underlying the lower methane emissions from sheep fed brassica forages. It is reported that feeding brassica forages to sheep can increase the concentration of free triiodothyronine (FT3) in serum, while the intramuscular injection of FT3 into sheep can reduce the mean retention time of digesta in the rumen. The short retention time of digesta is associated with low methane production. Glucosinolates (GSLs) are chemical components widely present in plants of the genus Brassica. After ruminants consume brassica forages, GSLs are broken down in the rumen. We hypothesize that GSLs or their breakdown products are absorbed into the blood and then may stimulate the secretion of thyroid hormone FT3 in ruminants, and the altered thyroid hormone concentration may change rumen physiology. As a consequence, the mean retention time of digesta in the rumen would be altered, resulting in a decrease in methane emissions. This hypothesis on mitigation mechanism is based on the manipulation of animal physiological parameters, which, if proven, will then support the expansion of this research area.

Animal, feed and rumen fermentation attributes associated with methane emissions from sheep fed brassica crops

Methane emissions from ruminants enhance global warming and lead to a loss of feed energy. The emissions are low when fed brassica crops, but the factors contributing to low emissions are unknown. A meta-analysis was conducted with individual animal data collected from seven experiments. In these experiments, methane emissions were measured using respiration chambers. Animal characteristics, feed chemical composition and rumen fermentation parameters were included for the analysis using multiple regression models. Feed intake level, animal live weight and age were animal factors that were weakly and negatively related to methane yield (g/dry matter intake). The duration in which sheep were fed brassica crops was a significant contributor in the model, suggesting that the effect on emissions diminishes with time. Among a range of feed chemical composition characters, acid detergent fibre and hot-water-soluble carbohydrate contributed significantly to the model, suggesting that both structural and soluble carbohydrates affect methane formation in the rumen. There was no significant correlation between the concentration of sulphate in brassicas and emissions, but nitrate was moderately and negatively correlated with methane yield (r = -.53). Short-chain fatty acid profiles in the rumen of animals fed brassicas were different from those fed pasture, but these parameters only moderately correlated to methane emissions (r = .42). Feeding forage rape resulted in low rumen pH. The pH before morning feeding was strongly correlated to methane yield (r = .90). Rumen pH, together with microbial communities mediated by pH, might lead to low emissions. Bacteria known to produce hydrogen were relatively less abundant in the rumen contents of brassica-fed animals than pasture-fed animals. In conclusion, animal and feed factors, rumen fermentation and microbial communities all affect methane emissions to some extent. The interactions of these factors with each other thus contribute to methane emissions from brassica-fed sheep.

Milk production responses, rumen fermentation, and blood metabolites of dairy cows fed increasing concentrations of forage rape (Brassica napus ssp. Biennis)

The aim of this study was to determine animal performance, rumen fermentation, and health-related blood metabolites of dairy cows in mid lactation fed with increasing levels (30 and 45%) of forage rape (FR) in the diet. Twelve pregnant multiparous lactating Holstein-Friesian dairy cows were randomly allocated to 1 of 3 dietary treatments in a replicated 3 × 3 Latin square design. The experiment was divided into three 21-d periods. For the control diet, 13.0 kg (dry matter, DM) of grass silage, 3.0 kg DM of commercial concentrate, 2.7 kg of DM cold-pressed extracted canola meal, and 0.45 kg DM of solvent-extracted soybean meal were offered daily. For the other two treatments, 30 and 45% of the DM from silage, canola meal, and commercial concentrate were replaced in equal proportions with FR. Data were analyzed individually using linear and quadratic orthogonal polynomials. Ingestive behavior was altered by the inclusion of FR. We observed a linear increase in eating time at the expense of rumination time. Nevertheless, total DM intake was not affected by dietary treatments, averaging 19.5 ± 0.24 kg of DM/d. Milk yield increased linearly with increasing concentration of FR in the diet. Thus, feed efficiency of cows (kg of milk/kg of DM intake) increased linearly with the percentage of FR in the diet. Inclusion of FR in the diet had no effect on milk composition or milk sensory characteristics. Mean rumen pH of cows decreased linearly from the control to the 45% FR diet; however, dietary treatments had no effect on the daily amount of time that rumen pH was below 5.8 (252 ± 71.4), indicating no risk of subacute ruminal acidosis. Concentrations of total volatile fatty acids in the rumen and molar proportions of acetate and butyrate were increased with FR inclusion, whereas the proportion of propionate was linearly reduced. Excretion of uric acid and total purine derivatives tended to be greater for cows fed FR, which resulted in a trend toward a linear increase in estimated microbial N flow. However, N use efficiency was not affected by FR inclusion. Although differences for some hematological measures (increased white blood cell and neutrophils counts) and a quadratic response for glutamate dehydrogenase for cows fed FR in the diet (decreased with inclusion of 30% and increased with 45% in the diet) were observed, all values were within appropriate ranges for dairy cows. These results indicated that including FR to dairy cow diets, up to 45% of diet DM, improved milk production due to changes in volatile fatty acids and predicted microbial N flow and had no negative effects on dairy cow health or sensory characteristics of milk.