Major Advances in Applied Dairy Cattle Nutrition

Production of cleavage-resistant phytase transgenic pigs by handmade cloning

With the rapid development of intensive animal husbandry in the livestock industry, large quantities of manure waste containing phytate phosphorus are being generated. Phytase can effectively solve the problem of high phosphorus pollution in the feces of monogastric animals. Enviropig, which produces phytase in the salivary glands and secretes the enzyme in the saliva, were first generated in 1999. However, phytase is easily inactivated during digestion. To address this problem, cleavage-resistant phytase transgenic pigs were generated using handmade cloning in this study. Transgene construction was improved and three cell lines carrying Cafp were obtained. In total, 810 blastocysts were generated and 712 good-quality were transferred into six recipients. Fourteen piglets were born, of which six survived after weaning. Polymerase chain reaction and sequencing results showed that seven (three live and four dead) of the fourteen piglets carried Cafp. Phytase activity in the saliva of the six live cloned pigs was tested at four months of age, and only one pig had 0.155 FTU/mL enzyme activity. The other five pigs may not have been activated in the transgenic parotid gland. Among all the transgenic pigs, the highest phosphorus digestion rate was 59.2% of intake, representing a 25.4% decrease in fecal emission compared to the average of controls. Immunohistochemical results on the three Cafp-positive pigs that died after six months of age showed that the transgene was only expressed in parotid glands, confirming tissue-specific gene expression. In conclusion, cleavage-resistant phytase transgenic pigs were successfully produced through handmade cloning. The cloned pigs offer a unique biological approach to managing phosphorus nutrition and environmental pollution in animal husbandry.

Effects of complete substitution of dietary grain and protein sources with by-products on the production performance of mid-lactation dairy cows fed diets based on barley silage under heat-stress conditions

This study evaluated the effects of replacing cereal grains and soybean meal with by-products (BY) on production performance, nutrient digestibility, ruminal fermentation, nutrient recovery, and eating and chewing behavior of moderate-producing dairy cows under heat-stress conditions. Twelve multiparous Holstein cows (116.7 ± 12.01 d in milk; 42.7 ± 5.06 kg/d milk yield; 665 ± 77 kg body weight; mean ± SD) were used in a replicated 3 × 3 Latin square with 28-d periods (21 d for diet adaptation and 7 d for sampling and data collection). Cows were fed a total mixed ration containing a 39.2:60.8 ratio of forage to concentrate throughout the experiment. All diets were formulated to be isoenergetic and isonitrogenous, with different concentrates. Diets were (1) control diet based on cereal grains (CON: ground corn and ground barley, plus soybean meal); (2) sugar-rich BY diet (S-BY-CM: beet pulp, citrus pulp, and liquid molasses, plus canola meal); and (3) cereal grain BY diet (CG-BY: rice bran, corn germ meal, wheat bran, barley sprout, and broken corn). Our results showed that replacing grains with BY increased neutral detergent fiber intake and digestibility but decreased starch intake, human-edible energy, and human-edible protein. Milk yield and dry matter intake (DMI) decreased more in cows fed the CG-BY diet compared with the other 2 treatments. In contrast, no significant differences were observed between the CON and S-BY-CM diets in terms of milk yield and DMI. The S-BY-CM diet increased energy-corrected milk production compared with the CG-BY diet (36.2 vs. 34.3 kg/d), but CG-BY enhanced feed conversion efficiency compared with the other 2 treatments. Although the S-BY-CM diet prolonged the eating and sorting of small particles, neither of the dietary treatments affected chewing activity or ruminal pH 4 h after feeding. Furthermore, both diets containing BY contributed to an increase in milk fat content in comparison to the CON group. Additionally, the CG-BY and S-BY-CM diets demonstrated better performance than the CON diet in terms of human-edible feed conversion efficiency for protein and energy. The results indicated that S-BY-CM can completely replace barley and corn grain in the diet of mid-lactating dairy cows exposed to heat-stress conditions without any negative effect on production and ruminal pH. However, the inclusion of CG-BY did impair DMI, milk yield, and digestibility of nutrients and is not recommended during heat-stress conditions.

[The lipidosis in the liver of the dairy cow: Part 2 Genetic predisposition and prophylaxis]

Hepatic lipidosis in dairy cows is the result of a disturbed balance between the uptake of non-esterified fatty acids (NEFA), their metabolism in the hepatocytes, and the limited efflux of TG as very-low-density lipoprotein (VLDL). Lipidosis and the associated risk for ketosis represents a consequence of selecting dairy cows primarily for milk production without considering the basic physiological mechanisms of this trait. The overall risk for lipidosis and ketosis possesses a genetic background and the recently released new breeding value of the German Holstein Friesian cows now sets the path for correction of this risk and in that confirms the assumed genetic threat. Ectopic fat deposition in the liver is the result of various steps including lipolysis, uptake of fat by the liver cell, its metabolism, and finally release as very-low-density lipoprotein (VLDL). These reactions may be modulated directly or indirectly and hence, serve as basis for prophylactic measures. The pertaining methods are described in order to support an improved understanding of the pathogenesis of lipidosis and ketosis. They consist of feeding a glucogenic diet, restricted feeding during the close-up time as well as supplementation with choline, niacin, carnitine, or the reduction of milking frequency. Prophylactic measures for the prevention of ketosis are also included in this discussion.

The gastrointestinal microbiome in dairy cattle is constrained by the deterministic driver of the region and the modified effect of diet

BACKGROUND

Dairy cattle (Bos taurus), especially Holstein cows, which are the highest-producing dairy animals and are widely bred to provide milk products to humans, rely critically on their associated gastrointestinal tract (GIT) microbiota to digest plant feed. However, the region-specific taxonomic composition and function of the GIT microbiome in dairy cattle and the mechanistic basis for the diet-induced effects remain to be elucidated.  RESULTS: We collected 120 digesta samples from 10 GIT regions of 12 Holstein cows fed forage- and grain-based diets and characterized their GIT microbiome via functional shotgun metagenomics and the resolution of metagenome-assembled genomes. Our results demonstrated that the GIT microbiome was mainly partitioned into three distinct clusters, four-chambered stomach, small intestine, and large intestine. Moreover, we found that the four-chambered stomach microbiome with the highest diversity had a strong ability to degrade recalcitrant polysaccharide substrates, underpinned by the prevalence of potential cellulosome--producing and plant-derived polysaccharide utilization loci-encoding consortia. In contrast, the post-gastric intestinal microbiome orchestrated alternative fermentation pathways to adapt to nutrient availability and energy acquisition. Diet shifts selectively modified the metabolic cascades of the microbiome in specific GIT regions, evidenced by the loss of fiber-degrading taxa and increased hydrogen sinks in propionate after grain introduction.

CONCLUSIONS

Our findings provide new insights into GIT microbial organization and function in dairy cattle by GIT regions and diet regimes, which offers clues for improving animal production and health in the future. Video Abstract.

Antimicrobial resistance determinants in silage

Animal products may play a role in developing and spreading antimicrobial resistance in several ways. On the one hand, residues of antibiotics not adequately used in animal farming can enter the human body via food. However, resistant bacteria may also be present in animal products, which can transfer the antimicrobial resistance genes (ARG) to the bacteria in the consumer’s body by horizontal gene transfer. As previous studies have shown that fermented foods have a meaningful ARG content, it is indicated that such genes may also be present in silage used as mass feed in the cattle sector. In our study, we aspired to answer what ARGs occur in silage and what mobility characteristics they have? For this purpose, we have analyzed bioinformatically 52 freely available deep sequenced silage samples from shotgun metagenome next-generation sequencing. A total of 16 perfect matched ARGs occurred 54 times in the samples. More than half of these ARGs are mobile because they can be linked to integrative mobile genetic elements, prophages or plasmids. Our results point to a neglected but substantial ARG source in the food chain.

Effects of replacement of corn silage and distillers' grain diets with hay during prepartum on the health and production performance of dairy heifers postpartum

In this study, we aimed to comprehensively evaluate the effects of prepartum replacement of corn silage and distillers' grain diets with hay on the postpartum health and production performance in dairy heifers. Pregnant Holstein dairy heifers were randomly assigned to two groups and fed different diets with the same net energy and protein concentrations. The low corn silage plus hay (CH) group diet mainly contained oat hay (28.5%), corn silage (25%) and folium ginkgo (23%). The high corn silage plus distillers' grains (CD) group diet contained corn silage (53.5%), distillers' grains (5%) and folium ginkgo (18%). Dairy heifers were fed from the beginning of pregnancy to the end of the transition period. Calf birthweight, postpartum morbidity, milk production and reproductive performance were determined. Compared with the cows in the CH group, those in the CD group presented increased calf birthweight and a high risk of some postpartum disorders (p < 0.05), particularly ketosis (37.63% vs. 24.54%) and retained placenta (9.41% vs. 3.92%). However, there was no difference between the groups in reproductive performance, including first timed artificial insemination (TAI) rate, date of TAI and conception rate of TAI. The lactation curves showed no difference in milk yield during the peak lactation period of primiparous cows between the CH and CD groups; the total milk production was 33.39 kg and 33.19 kg respectively. Notably, the time to peak milk production was delayed in the CD group. It can be concluded that replacing corn silage and distillers' grains with hay can reduce postpartum morbidity in dairy heifers and shorten the time to peak milk production.

Boosting animal performance, immune index and antioxidant status in post-weaned bull calves through dietary augmentation of selective traditional medicinal plants

Traditional medicinal plants (TMP) are considered valuable alternatives to hazardous synthetic chemical utilized as animal growth promoters. This study aimed to evaluate effects of dietary supplementation of seed and leaf powder (75:25) of three Bangladeshi TMP viz. Emblica officinalis Gaertn., Terminalia bellirica Gaertn. Roxb., and Terminalia chebula Retz. on growth performance, digestibility of nutrients, hematological indices, immune index and antioxidant status in post-weaned bull calves. Dietary treatments: TMP1 (basal diet = green grass + concentrate), TMP2 (basal diet + 0.5% mixture of seed and leaf (75:25) of E. officinalis Gaertn.), TMP3 (basal diet + 0.5% mixture of seed and leaf (75:25) of T. bellirica Gaertn. Roxb.), and TMP4 (basal diet + 0.5% mixture of seed and leaf (75:25) of T. chebula Retz.). Supplementation of TMP significantly (p < 0.10) improved weight gain without affecting digestibility. Hematological indices did not change much by treatment of TMP except for enhancement of monocyte (p < 0.10) and platelet percentage (p < 0.05). A reduction in IGF, enhancement (p < 0.05) of lymphocyte proliferation, and IgG were recorded in TMP2, TMP3 and TMP4 compared to TMP1. Decreasing (p < 0.05) trend of interleukins-1 and 6, and an elevation of TNF-α and antioxidant status were recorded in the TMP2, TMP3, and TMP4 in comparison to TMP1. An elevated level of total antioxidant and glutathione peroxidase activities were found in calves treated with TMP2, TMP3, and TMP4 (p < 0.05) relative to TMP1. Taken together, our results indicate that supplementation of feed with Bangladeshi TMP promoted growth and some health indices like immune-advocating efficacy of post-weaned bull calves.

A review on the potentials of using feeds rich in water-soluble carbohydrates to enhance rumen health and sustainability of dairy cattle production

Cows are adapted to degrade structural plant carbohydrates (SC), such as cellulose and hemicelluloses, prevailing in grasses. Yet, the need for energy-dense diets in many intensive dairy production systems has shifted the dairy cattle's diet from SC-rich to high levels of starch. Feeding of starch-rich diets increases the risk of ruminal acidosis in cows, and feeding starch in the form of grains intensifies the competition over cereal grains and arable land among different livestock species, as well as between livestock and humans. Besides cellulose and hemicelluloses, grasses are also often rich in water-soluble carbohydrates (WSC), which comprise mono-, di-, oligo- and polysaccharides (fructans). Although the ruminal fermentation profile of mono- and disaccharides resembles that of starch, the degradation of oligo- and polysaccharides is slower, and their fermentation elicits a rather protecting effect on ruminal pH. When harvested in an early phase (i.e. ear emergence), grass hay and silages can reach WSC levels up to 150-200 g kg^-1 dry matter and energy levels close to starch-rich diets, allowing a significantly reduced inclusion of concentrate supplements. By doing so, this will enhance both rumen health and the sustainability of milk production. However, because the WSC are chemically very heterogeneous, the patterns and extent of their ruminal fermentation are difficult to predict without a clear analytical characterization. This review article aims to summarize both the benefits and potentials, as well as the challenges, with respect to using WSC-rich feedstuffs in the nutrition of dairy cattle and their effects on ruminal fermentation characteristics and milk production. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Feeding dairy cows bakery by-products enhanced nutrient digestibility, but affected fecal microbial composition and pH in a dose-dependent manner

We reported recently that adding bakery by-products (BP) to the diets of dairy cows up to 30% improved performance and rumen pH, but caused major shifts in the nutrient profile and availability, likely modifying nutrient degradation patterns throughout the gastrointestinal tract. The aim of this study was to investigate the effects of the gradual replacement of cereals by BP on the apparent total-tract digestibility (ATTD), the fermentation patterns, and the microbial community in feces of dairy cows. Twenty-four mid-lactating Simmental cows (149 ± 22.3 days in milk, 756 ± 89.6 kg of initial body weight) were fed a total mixed ration ad libitum (fresh feed was offered twice per day) containing a 50:50 ratio of forage to concentrate (dry matter basis) throughout the experiment. The trial lasted 5 wk, whereby the first week was used for baseline measurements, in which all cows received the same diet, without BP. Cows were then randomly allocated into 3 groups differing in the BP content of diets (0% BP, 15% BP, and 30% BP on a DM basis) and fed for 4 wk. Fecal samples were taken for analysis of pH, volatile fatty acids (VFA), and 16S rRNA gene sequencing. The inclusion of BP resulted in an increase of ether extract and sugars, and a reduction of starch and neutral detergent fiber in the diet. Feeding BP linearly increased the ATTD of almost all nutrients resulting in up to 2 kg more digestible organic matter intake (DOMI). Increasing BP level up to 30% increased fecal total VFA concentration and decreased the pH. The proportion of butyrate in feces increased linearly, but the proportion of all other VFA was not affected by BP-feeding. The richness and diversity indices of the fecal microbiota linearly declined by the inclusion of BP. The cellulolytic phyla Fibrobacteres decreased, whereas amylolytic phyla, such as Proteobacteria, increased. Overall, results showed that feeding BP linearly increased ATTD and DOMI, but impaired fecal microbial diversity and pH. In the interest of the optimization of BP inclusion in the dairy cows' feeding, a dietary level between 15 to 30% of BP might be a better compromise than 30% in terms of an enhanced DOMI and performance with still lowered risk of hindgut dysbiosis, but this will require further investigations.

Discrimination of geographical origin and species of China's cattle bones based on multi-element analyses by inductively coupled plasma mass spectrometry

Consumers have an increasing concern in the provenance of the foods they consume. Methods for discriminating geographical origins and species of cattle bone product are essential to provide veracious information for consumers and avoid the adulteration and inferior problems. In this study, 50 element contents of a total of 143 cattle bone samples from eight producing regions in China, were determined by inductively coupled plasma mass spectrometry (ICP-MS). Element contents were used as chemical indicators to discriminate species and geographical origins of cattle bone samples by multivariate data analysis, including hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). The K-fold cross validation accuracy for species and geographical origin discrimination was 99.3% and 94.5%, respectively. This study reveals that multi-element analysis accompanied by LDA is an effective technique to ensure the information reliability of cattle bone samples, and this strategy may be a potential tool for standardizing market.

Maintaining Optimal Mammary Gland Health and Prevention of Mastitis

In dairy industry, quality of produced milk must be more important than quantity without a high somatic cells count (SCC) or pathogens causing mastitis of dairy cows and consumer diseases. Preserving the good health of dairy cows is a daily challenge for all involved in primary milk production. Despite the increasing level of technological support and veterinary measures, inflammation of the mammary gland–mastitis, is still one of the main health problems and reasons for economic losses faced by cow farmers. The mammary gland of high-yielding dairy cows requires making the right decisions and enforcing the proper measures aimed at minimizing external and internal factors that increase the risk of intramammary infection. Due to the polyfactorial nature of mastitis related to its reduction, the effectiveness of commonly used antimastitis methods tends to be limited and therefore it is necessary to find the areas of risk in udder health programs and monitoring systems. Only by implementing of complete udder health programs should be accompanied by research efforts to further development these complete udder health control. The present review analyses the current knowledge dealing with damping and prevention of mastitis include SCC control, proper nutrition, housing and management, milking and drying as practiced in dairy farming conditions. This information may help to improve the health of the mammary gland and the welfare of the dairy cows as well as the production of safe milk for consumers.

Addition of straw to the early-lactation diet: Effects on feed intake, milk yield, and subclinical ketosis in Holstein cows

This study evaluated feed intake, milk yield, and subclinical ketosis in dairy cows in early lactation fed 2 different diets postpartum. Cows are typically offered a high-energy ration immediately after calving. We compared a conventional high-energy total mixed ration (TMR) with a transition ration that contained chopped straw. We predicted that adding chopped straw would increase dry matter intake, milk production, and indicators of energy metabolism during the first 3 wk of lactation compared to cows fed a conventional high-energy TMR. We also predicted that carryover effects would be likely for at least 2 wk after treatment ended. A total of 68 mixed-age Holstein cows were enrolled in the study 3 wk before their expected calving. All cows were managed on a single high-forage diet during the dry period. At calving, cows were allocated to 1 of the 2 diets: half to the conventional high-energy TMR (CTMR; n = 34; net energy for lactation = 1.61 Mcal/kg; neutral detergent fiber = 31.7%), and the other half to a high-forage TMR containing chopped wheat straw, equivalent to 4.27% dry matter (STMR; n = 34; net energy for lactation = 1.59 Mcal/kg; neutral detergent fiber = 33.7%) for 3 wk after calving. Cows on STMR were then shifted to CTMR for the next 2 wk to study short-term residual effects on the performance of cows. Treatments were balanced for parity, body condition score, and body weight. Feed intake was measured daily from 2 wk before to 5 wk after calving using automatic feed bins. Blood was sampled twice weekly from 2 wk before to 5 wk after calving, and β-hydroxybutyrate and glucose were measured in serum samples. Subclinical ketosis was identified using a threshold of β-hydroxybutyrate ≥1.0 mmol/L in wk 1 after calving and ≥1.2 mmol/L in wk 2 to 5 after calving. Cows were milked twice daily, and weekly samples (composite samples of morning and afternoon milkings) were analyzed to determine total solids, fat, protein, lactose, and somatic cell count. Data were analyzed in 2 separate periods: the treatment phase (wk +1, +2, and +3) and the post-treatment phase (wk +4 and +5). The addition of straw to the TMR negatively affected the dry matter intake of STMR cows during wk 2 and 3 of lactation. Daily milk yield during the first 5 wk of lactation was lower in STMR cows than in CTMR cows. Concentrations of β-hydroxybutyrate were higher in CTMR cows than in STMR cows during wk 1, but this effect was reversed during wk 2 and 3 of lactation. By 21 d in milk, STMR cows had a greater risk of developing subclinical ketosis than CTMR cows. Adding chopped wheat straw to the TMR during the first 21 d after calving lowered dry matter intake and provided no metabolic or production benefits to lactating dairy cattle.

Genetic mechanisms underlying feed utilization and implementation of genomic selection for improved feed efficiency in dairy cattle

The economic importance of genetically improving feed efficiency has been recognized by cattle producers worldwide. It has the potential to considerably reduce costs, minimize environmental impact, optimize land and resource use efficiency, and improve the overall cattle industry’s profitability. Feed efficiency is a genetically complex trait that can be described as units of product output (e.g., milk yield) per unit of feed input. The main objective of this review paper is to present an overview of the main genetic and physiological mechanisms underlying feed utilization in ruminants and the process towards implementation of genomic selection for feed efficiency in dairy cattle. In summary, feed efficiency can be improved via numerous metabolic pathways and biological mechanisms through genetic selection. Various studies have indicated that feed efficiency is heritable, and genomic selection can be successfully implemented in dairy cattle with a large enough training population. In this context, some organizations have worked collaboratively to do research and develop training populations for successful implementation of joint international genomic evaluations. The integration of “-omics” technologies, further investments in high-throughput phenotyping, and identification of novel indicator traits will also be paramount in maximizing the rates of genetic progress for feed efficiency in dairy cattle worldwide.

Poultry by-product meal as a replacement to xylose-treated soybean meal in diet of early- to mid-lactation Holstein cows

The objectives were to compare the effectiveness of poultry by-product meal (PBM) with xylose-treated soybean meal (x-SBM) as a conventional protein source and rumen-undegraded protein (RUP):rumen-degraded protein (RDP) ratio on nutrient digestibility, nitrogen metabolism, and production of early- to mid-lactation Holsteins. Twelve multiparous cows averaging (mean ± SD) 50 ± 9 days in milk were randomly assigned to a replicated 4 × 4 Latin square design within a 2 × 2 factorial arrangement of treatments. Each period was 28 days in length. Treatments were RUP sources (PBM or x-SBM) with either a high or a low RUP:RDP ratio (high ratio = 40:60 or low ratio = 36:64; based on % of crude protein (CP)). Experimental diets were balanced to be similar in protein and energy contents (CP = 16.7% of DM; NEL = 1.67 Mcal/kg DM). Prior to diet formulation, an in situ pilot experiment was conducted to estimate the RUP fractions of x-SBM and PBM as 63.9% and 54.1% of CP, respectively. Treatments had no effect on ruminal pH and total volatile fatty acid (VFA) and molar percentage of individual VFAs. Treatments had no effect on total tract apparent digestibility of DM, OM, and neutral detergent fiber (NDF), with the exception of N that was greater in diets with a low RUP:RDP ratio (68.2 vs. 70.1% of DM). DM consumption was 0.70 kg/day higher when cows were fed PBM diet compared with x-SBM diet. No treatment effect was observed on milk yield and milk composition; however, milk protein yield and milk urea N were greater in cows fed PBM. Inclusion of PBM in the diet in substitution to x-SBM resulted in increased blood levels of urea N, cholesterol, and non-esterified fatty acid (NEFA). There was no interaction between the RUP source and the RUP:RDP ratio for urinary and fecal N excretion. Efficiency of N utilization expressed as milk N secretion as a proportion of N intake tended to be greater in cows fed PBM. Feeding diets with a low ratio of RUP:RDP increased efficiency of milk production expressed as milk yield as a proportion of total N excretion (fecal and urinary N). Feeding a diet with PBM supported milk production comparable with x-SBM and had positive effects on feed intake, milk protein yield, and milk N efficiency.

Phytogenic Additives Can Modulate Rumen Microbiome to Mediate Fermentation Kinetics and Methanogenesis Through Exploiting Diet-Microbe Interaction

Ruminants inhabit the consortia of gut microbes that play a critical functional role in their maintenance and nourishment by enabling them to use cellulosic and non-cellulosic feed material. These gut microbes perform major physiological activities, including digestion and metabolism of dietary components, to derive energy to meet major protein (65-85%) and energy (ca 80%) requirements of the host. Owing to their contribution to digestive physiology, rumen microbes are considered one of the crucial factors affecting feed conversion efficiency in ruminants. Any change in the rumen microbiome has an imperative effect on animal physiology. Ruminal microbes are fundamentally anaerobic and produce various compounds during rumen fermentation, which are directly used by the host or other microbes. Methane (CH4) is produced by methanogens through utilizing metabolic hydrogen during rumen fermentation. Maximizing the flow of metabolic hydrogen in the rumen away from CH4 and toward volatile fatty acids (VFA) would increase the efficiency of ruminant production and decrease its environmental impact. Understanding of microbial diversity and rumen dynamics is not only crucial for the optimization of host efficiency but also required to mediate emission of greenhouse gases (GHGs) from ruminants. There are various strategies to modulate the rumen microbiome, mainly including dietary interventions and the use of different feed additives. Phytogenic feed additives, mainly plant secondary compounds, have been shown to modulate rumen microflora and change rumen fermentation dynamics leading to enhanced animal performance. Many in vitro and in vivo studies aimed to evaluate the use of plant secondary metabolites in ruminants have been conducted using different plants or their extract or essential oils. This review specifically aims to provide insights into dietary interactions of rumen microbes and their subsequent consequences on rumen fermentation. Moreover, a comprehensive overview of the modulation of rumen microbiome by using phytogenic compounds (essential oils, saponins, and tannins) for manipulating rumen dynamics to mediate CH4 emanation from livestock is presented. We have also discussed the pros and cons of each strategy along with future prospective of dietary modulation of rumen microbiome to improve the performance of ruminants while decreasing GHG emissions.

Feeding of bakery by-products in the replacement of grains enhanced milk performance, modulated blood metabolic profile, and lowered the risk of rumen acidosis in dairy cows

Leftover bakery by-products (BP) from bakeries and supermarkets may serve as energy-rich ingredient in ruminant diets. The aim of the present study was to evaluate the effect of the successive substitution of cereal grains by BP on dry matter (DM) intake, milk production, and metabolic health as well as ruminal pH and eating and chewing behavior of dairy cows. Twenty-four lactating Simmental cows (149 ± 22.3 d in milk, lactation number 2.63 ± 1.38, 756 ± 89.6 kg of initial body weight) were fed a total mixed ration containing a 50:50 ratio of forage to concentrate throughout the experiment (35 d). During the first week, all cows received a control diet (without BP) as a baseline (d -7 to 0). In the next 4 wk (d 1 to 28), cows were allocated to 3 groups differing in the BP concentrations of diets [0% BP (CON), 15% BP, and 30% BP on a DM basis]. The DM intake and reticuloruminal pH were continuously measured. Blood and milk samples were taken every week, but only results from the experimental period (d 21 and 28) were used for statistical analyses, whereas results from the baseline were considered covariates. Diet analyses showed that BP inclusion increased the ether extract and sugar contents, whereby starch and neutral detergent fiber decreased. Experimental data showed that feeding BP in the diet increased DM intake. Furthermore, the cows fed 30% BP produced roughly 4 kg/d more milk and energy-corrected milk than the CON cows. The milk urea nitrogen was lower in cows fed the BP. Feeding BP reduced the blood glucose and insulin concentrations, whereas nonesterified fatty acids, β-hydroxybutyrate, and cholesterol increased linearly. Cows fed 15% BP had the shortest period of time in which ruminal pH was below 5.8, in contrast to CON cows (+188 min/d). Taken together, the results suggest that the inclusion of up to 30% BP in the diets of mid-lactation dairy cows shifted the nutrient profile from a glucogenic diet to a lipogenic diet, holding the potential to enhance performance and lower the risk of subacute ruminal acidosis in dairy cows.

Nutrient digestibility, nitrogen excretion, and milk production of mid-lactation Jersey × Friesian cows fed diets containing different proportions of rumen-undegradable protein

The present study was planned to test the hypothesis that feeding lactating dairy cattle with varying levels of rumen-undegradable protein (RUP) can enhance protein utilization, milk production, milk protein, and nitrogen (N) excretion. Forty mid-lactating crossbred (Jersey × Friesian) cattle were randomly divided into four groups. Four treatment diets were formulated to contain 30%, 40%, 50%, and 60% RUP of crude protein. Dry matter (DM) and crude protein intakes were significantly reduced with increasing dietary RUP levels. Crude protein digestibility increased linearly with incremental increases in dietary RUP levels. Cattle fed 60% RUP showed a linear decrease in N intake compared to that in the other groups. A linear decrease in urinary N and linear increases in net N, milk N, and N-use efficiency were observed with increasing dietary RUP levels. Actual milk, energy-corrected milk, and 4% fat-corrected milk yields (kg/day) increased linearly with an increasing degradability of protein. However, milk protein, solids not fat and total solids, as well as the yields of protein, fat, and lactose, showed significant increases with increased RUP supplementation. Collectively, the results indicate that formulating dairy cow diets to contain 60% RUP results in better lactating performance and N-use efficiency and lower N excretion.

Maximizing Lucerne (Medicago sativa) Pasture Intake of Dairy Cows: 1-the Effect of Pre-Grazing Pasture Height and Mixed Ration Level

Simple Summary

Pre-grazing pasture height has significant impact on intake rate and intake in grazing dairy herds, and the ideal pre-grazing pasture height varies between pasture species. Defining the ideal pre-grazing pasture height of lucerne pasture has potential to significantly increase milk production of cows on sub-tropical partial mixed ration (PMR) dairies in Australia. Pasture intake of dairy cows was highest when the pre-grazing pasture height of lucerne was 39 cm and a proportion of the pasture remained un-grazed, irrespective of the amount of mixed ration offered.

Abstract

The effect of lucerne (Medicago sativa L.) pre-grazing pasture height on pasture intake and milk production was investigated in a sub-tropical partial mixed ration (PMR) dairy system in south-east Queensland, Australia. The experiment involved a 26-day adaptation period followed by an eight-day measurement period during April and May 2018. Twenty-four multiparous Holstein-Friesian dairy cows were offered a mixed ration at either 7 (low) or 14 (high) kg dry matter (DM)/cow/day and allocated pastures at pre-grazing heights ranging from 23 to 39 cm. The targeted pasture intake was 14 and 7 kg DM/cow/day for cows offered the low and high mixed ration allowances respectively, with a total intake target of 21 kg DM/cow/day. Pasture structure did not limit pasture intake as the all groups left at least 12% of the allocated area ungrazed, and therefore could selectively graze pasture. There was no significant difference in intake between mixed ration levels, however intake had a positive linear relationship with pre-grazing pasture height. For every one cm increase in pasture height, intake increased by 0.3 kg DM/cow/day. Using a grazing strategy that ensures the some pasture remains ungrazed and the pre-grazing height of lucerne is approximately 39 cm above ground level will maximise pasture intake in sub-tropical PMR dairy systems.

The effects of improved performance in the U.S. dairy cattle industry on environmental impacts between 2007 and 2017

The U.S. dairy industry considerably reduced environmental impacts between 1944 and 2007, primarily through improved dairy cow productivity. However, although milk yield per cow has increased over the past decade, whole-system environmental impact analyses have not been conducted over this time period, during which environmental modeling science has improved considerably. The objective of this study was to compare the environmental impact of U.S. dairy cattle production in 2007–2017. A deterministic model based on population demographics, metabolism, and nutrient requirements of dairy cattle was used to estimate resource inputs, nutrient excretion, and greenhouse gas (GHG) emissions per 1.0 × 10⁶ t (one million metric t or MMT) of energy-corrected milk (ECM) produced in 2007 and 2017. System boundaries extended from the manufacture and transport of cropping inputs to milk at the farm gate. Milk transport, processing, and retail were not included. Dairy systems were modeled using typical management practices, herd population dynamics, and production data from U.S. dairy farms. Cropping data were sourced from national databases. The resources required to produce 1.0 MMT ECM in 2017 were considerably reduced relative to those required in 2007, with 2017 production systems using 74.8% of the cattle, 82.7% of the feedstuffs, 79.2% of the land, and 69.5% of the water as compared to 2007. Waste outputs were similarly reduced, with the 2017 U.S. dairy industry producing 79.4%, 82.5%, and 85.7% of the manure, N, and P excretion, respectively. Dairy production in 2017 emitted 80.9% of the CH₄ and 81.5% of the N₂O per 1.0 MMT ECM compared to 2007. Enteric and manure emissions contributed the major proportion (80%) of GHG emissions per unit of milk, with lesser contributions from cropping (7.6%) and fertilizer application (5.3%). The GHG emissions per 1.0 MMT ECM produced in 2017 were 80.8% of equivalent milk production in 2007. Consequently, although total U.S. ECM production increased by 24.9% between 2007 and 2017, total GHG emissions from this milk production increased by only 1.0%. In line with previous historical analyses, the U.S. dairy industry has made remarkable productivity gains and environmental progress over time. To maintain this culture of continuous improvement, the dairy industry must build on gains made to date and demonstrate its commitment to reducing environmental impacts while improving both economic viability and social acceptability.

Moisture content of high-straw dry cow diets affects intake, health, and performance of transition dairy cows

The objective of this study was to determine the effect of adding water to a high-straw dry cow diet on feeding behavior, health, and performance of dairy cows. Holstein cows (n = 40) entering their second or greater lactation were enrolled at dry off (∼45 d before expected calving) and assigned to 1 of 2 dietary treatments, consisting of a high-straw dry cow total mixed ration [TMR; 36% wheat straw, 41% corn silage, 23% pellet, on a dry matter (DM) basis, formulated for 11.6% crude protein, 1.35 Mcal/kg net energy for lactation] with (1) no water (CON; n = 20; DM = 53.4%) or (2) water added to decrease the DM by ∼10 percentage points (wet diet, WD; n = 20; DM = 45.4%). Upon calving, all cows were fed the same lactating TMR (45.2% DM, 14.9% crude protein, 1.68 Mcal/kg net energy for lactation) and followed for 28 d. Dry matter intake, feeding behavior, and rumination activity were recorded automatically. Fresh TMR and orts samples were collected 2×/wk to determine differences in sorting. A particle separator was used to separate feed samples into 4 fractions: long (>19 mm), medium (<19, >8 mm), short (<8, >4 mm), and fine (<4 mm) particles. Feed sorting was calculated as actual intake of each particle fraction expressed as a % of predicted intake. Cows fed WD had greater DM intake during the dry period than cows fed CON (CON = 13.4 ± 0.24, WD = 14.2 ± 0.24 kg/d), but rumination did not differ (CON = 522.2 ± 8.48, WD = 518.5 ± 8.69 min/d) between treatments. Cows fed WD tended to consume their feed faster (CON = 0.08 ± 0.001, WD = 0.09 ± 0.001 kg of DM/min) compared with CON cows. Regardless of treatment, cows sorted against the longest ration particles, with cows fed CON sorting more against these (CON = 81.1 ± 2.51%, WD = 94.9 ± 2.58%). Cows fed CON tended to sort more in favor of the medium particles than those fed WD (CON = 105.0 ± 0.36%, WD = 104.2 ± 0.37%). Postcalving DM intake and feeding behavior were not affected by dry diet treatment. Cows fed WD experienced a less rapid daily decline in rumen pH during the first 7 d after calving compared with those fed the CON diet. The results suggest that increasing the moisture content of high-straw dry cow diets, by adding water, may improve intake and reduce sorting against the longest ration particles, which may help promote consistency in targeted nutrients consumed during the dry period and greater rumen health in early lactation.

Invited review: Metabolic challenges and adaptation during different functional stages of the mammary gland in dairy cows: Perspectives for sustainable milk production

Milk production of dairy cows has increased markedly during recent decades and continues to increase further. The evolutionarily conserved direction of nutrients to the mammary gland immediately after calving provided the basis for successful selective breeding toward higher performance. Considerable variation in adaptive responses toward energy and nutrient shortages exists; however, this variation in adaptability recently gained interest for identifying more metabolically robust dairy cows. Metabolic challenges during periods of high milk production considerably affect the immune system, reproductive performance, and product quality as well as animal welfare. Moreover, growing consumer concerns need to be taken into consideration because the public perception of industrialized dairy cow farming, the high dependency on feed sources suitable for human nutrition, and the apparently abundant use of antibiotics may affect the sales of dairy products. Breeding for high yield continues, but the metabolic challenges increasingly come close to the adaptational limits of meeting the mammary gland's requirements. The aim of the present review is to elucidate metabolic challenges and adaptational limitations at different functional stages of the mammary gland in dairy cows. From the challenges and adaptational limitations, we derive perspectives for sustainable milk production. Based on previous research, we highlight the importance of metabolic plasticity in adaptation mechanisms at different functional stages of the mammary gland. Metabolic adaptation and plasticity change among developing, nonlactating, remodeling, and lactational stages of the mammary gland. A higher metabolic plasticity in early-lactating dairy cows could be indicative of resilience, and a high performance level without an extraordinary occurrence of health disorders can be achieved.

Effects of live yeast dietary supplementation on hormonal profile, ovarian follicular dynamics, and reproductive performance in dairy cows exposed to high ambient temperature

Two experiments were conducted to investigate the effects of dietary supplementation with live yeast culture on hormonal profile, ovarian follicular dynamics and reproductive performance of lactating dairy cows exposed to high ambient temperature. In Expt. 1, Holstein cows were fed a diet with (n = 6) or without (n = 6) 4 g yeast/h/d from 21 d before expected calving date until 8 weeks postpartum. Concentrations of glucose, insulin, insulin like growth factor-I (IGF-I), estradiol-17β (E-17β) and progesterone (P4) were determined in plasma, and transrectal ultrasonography was used to monitor ovarian follicular dynamics. In Expt. 2, 150 Holstein cows (75/dietary group) received same diets as Expt. 1 with the exception that diets were fed from d 1 to d 70 postpartum. The effect of dietary treatments on reproductive performance was examined. In Expt. 1, plasma IGF concentrations during dietary treatment were higher (P = 0.05) in cows fed diets supplemented with yeast. On d 60 postpartum, average plasma concentrations of glucose (48.3 vs. 41.0 mg/dL) and insulin (0.90 vs. 0.23 μU/mL), were also greater in cows fed diets supplemented with yeast compared to that in cow fed diets without supplementation. Similarly, plasma concentrations of E-17β at estrus (P = 0.016) and P4 on d 10 of the estrous cycle (P = 0.021) were greater in yeast-supplemented cows. Moreover, yeast supplementation resulted on average in an estrous cycle 2.6 d shorter (P = 0.05) and in the development of larger ovulatory follicles (18.4 vs. 17.2 mm in diameter; P < 0.01). In Expt. 2, days open were fewer and the proportion of pregnant cows at 120 and 150 d postpartum were greater (P < 0.01) in cows fed diets supplemented with yeast compared to those receiving diets without yeast. In summary, cows fed diets supplemented with yeast had greater plasma IGF-I, E-17β and P4 concentrations, larger ovulatory follicles, shorter estrous cycles, and improved reproductive performance. Therefore, live yeast dietary supplementation could enhance lactating dairy cow's fertility during heat stress through improvement in hormonal profile and development of larger ovulatory follicles.

A 100-Year Review: Total mixed ration feeding of dairy cows

Total mixed rations (TMR) as we know them today did not exist in 1917. In fact, TMR are an invention of primarily the last half of the past 100 yr. Prior to that time many dairy herds were fed only forages, but dairy producers started moving toward TMR feeding as milk production per cow increased, herds became larger, freestall and large-group handling of cows became more common, and milking parlors became more prevalent. The earliest known reports in the Journal of Dairy Science of feeding "complete rations" or TMR may have appeared in the 1950s, but those studies were often reported only as abstracts at annual meetings of the American Dairy Science Association or in extension-type publications. The earliest full-length article on TMR in the journal was published in 1966. An advantage of feeding TMR as opposed to feeding forages supplemented with concentrates is the opportunity to make every bite of feed essentially a complete, nutritionally balanced diet for all cows. Nutritionally related off-feed (e.g., ingredient separation due to poor mixing, feed sorting by the animal, and so on), milk fat depression, and other digestive upsets were less likely to occur with TMR feeding. Feed mixer wagons, feed particle sizes, moisture content of diets, and other factors were not concerns before TMR feeding but are concerns today. Today, most dairy herds, especially larger herds in the United States and elsewhere, feed TMR.

Symposium review: Understanding diet-microbe interactions to enhance productivity of dairy cows

Ruminants are dependent on the microbiota (bacteria, protozoa, archaea, and fungi) that inhabit the reticulo-rumen for digestion of feedstuffs. Nearly 70% of energy and 50% of protein requirements for dairy cows are met by microbial fermentation in the rumen, emphasizing the need to characterize the role of microbes in feed breakdown and nutrient utilization. Over the past 2 decades, next-generation sequencing technologies have allowed for rapid expansion of knowledge concerning microbial populations and alterations in response to forages, concentrates, supplements, and probiotics in the rumen. Advances in gene sequencing and emerging bioinformatic tools have allowed for increased throughput of data to aid in our understanding of the functional relevance of microbial genomes. In particular, metagenomics can identify specific genes involved in metabolic pathways, and metatranscriptomics can describe the transcriptional activity of microbial genes. These powerful approaches help untangle the complex interactions between microbes and dietary nutrients so that we can more fully understand the physiology of feed digestion in the rumen. Application of genomics-based approaches offers promise in unraveling microbial niches and respective gene repertoires to potentiate fiber and nonfiber carbohydrate digestion, microbial protein synthesis, and healthy biohydrogenation. New information on microbial genomics and interactions with dietary components will more clearly define pathways in the rumen to positively influence milk yield and components.

The effect of Saccharomyces cerevisiae on in vitro growth and fermentation of Selenomonas ruminantium and Megasphaera elsdenii

Stimulation of lactate utilization by Selenomonas ruminantium and Megasphaera elsdenii may help in reducing problems associated with rumen acidosis. The objective of this study was to determine the effect of a Saccharomyces cerevisiae live culture and Saccharomyces cerevisiae fermentation products on in vitro growth and fermentation of lactate-utilizing ruminal bacteria, S. ruminantium (ATCC 19205) and M. elsdenii (ATCC 25940). The cultures were run for 0, 6, 12, 24 and 48 h under anaerobic conditions on a growth medium supplemented with a yeast live culture (SC) or with yeast fermentation products (SCFP) and, as reference, on the same medium without supplementation (CON). Neither SC nor SCFP had a significant effect on the growth of S. ruminantium after 6, 12 and 24 h of incubation, but the live yeast culture significantly (P≤0.05) improved the growth of these bacteria after 48 h of incubation. The yeast fermentation products significantly (P≤0.05) decreased pH and increased lactate synthesis by S. ruminantium. The Saccharomyces cerevisiae live culture significantly improved the growth of M. elsdenii after 12 and 24 h of incubation, and the S. cerevisiae fermentation products increased its growth after 48 h. The After 24 and 48 h of incubation the Saccharomyces cerevisiae live culture reduced the concentration of total volatile fatty acids (VFA), while caproate was the main product of in vitro fermentation of M. elsdenii (P≤0.05). Saccharomyces cerevisiae live cultures may improve microbial fibre fermentation in the rumen by maintaining optimal pH conditions.

Effects of Saccharomyces cerevisiae fermentation products on performance and rumen fermentation and microbiota in dairy cows fed a diet containing low quality forage

BACKGROUND

A possible option to meet the increased demand of forage for dairy industry is to use the agricultural by-products, such as corn stover. However, nutritional value of crop residues is low and we have been seeking technologies to improve the value. A feeding trial was performed to evaluate the effects of four levels of Saccharomyces cerevisiae fermentation product (SCFP; Original XP; Diamond V) on lactation performance and rumen fermentation in mid-lactation Holstein dairy cows fed a diet containing low-quality forage. Eighty dairy cows were randomly assigned into one of four treatments: basal diet supplemented with 0, 60, 120, or 180 g/d of SCFP per head mixed with 180, 120, 60, or 0 g of corn meal, respectively. The experiment lasted for 10 wks, with the first 2 weeks for adaptation.

RESULTS

Dry matter intake was found to be similar (P > 0.05) among the treatments. There was an increasing trend in milk production (linear, P ≤ 0.10) with the increasing level of SCFP supplementation, with no effects on contents of milk components (P > 0.05). Supplementation of SCFP linearly increased (P < 0.05) the N conversion, without affecting rumen pH and ammonia-N (P > 0.05). Increasing level of SCFP linearly increased (P < 0.05) concentrations of ruminal total volatile fatty acids, acetate, propionate, and butyrate, with no difference in molar proportion of individual acids (P > 0.05). The population of fungi and certain cellulolytic bacteria (Ruminococcus albus, R. flavefaciens and Fibrobacter succinogenes) increased linearly (P < 0.05) but those of lactate-utilizing (Selenomonas ruminantium and Megasphaera elsdenii) and lactate-producing bacteria (Streptococcus bovis) decreased linearly (P ≤ 0.01) with increasing level of SCFP. The urinary purine derivatives increased linearly (P < 0.05) in response to SCFP supplementation, indicating that SCFP supplementation may benefit for microbial protein synthesis in the rumen.

CONCLUSIONS

The SCFP supplementation was effective in maintaining milk persistency of mid-lactation cows receiving diets containing low-quality forage. The beneficial effect of SCFP could be attributed to improved rumen function; 1) microbial population shift toward greater rumen fermentation efficiency indicated by higher rumen fungi and cellulolytic bacteria and lower lactate producing bacteria, and 2) rumen microbial fermentation toward greater supply of energy and protein indicated by greater ruminal VFA concentration and increased N conversion. Effects of SCFP were dose-depended and greater effects being observed with higher levels of supplementation and the effect was more noticeable during the high THI environment.

Effects of water addition to total mixed ration on water intake, nutrient digestibility, wool cortisol and blood indices in Corriedale ewes

OBJECTIVE

The objective of this study was to determine the effect of adding water to total mixed ration (TMR) on fresh water intake, nutrient digestibility, wool cortisol, and blood indices in Corriedale ewes under hot and humid conditions.

METHODS

Nine non-pregnant Corriedale ewes (ave. body weight = 41±3.5 kg) were individually fed diets based on maintenance requirements in metabolic crates. Ewes were assigned to three treatment groups according to a triplicate 3×3 Latin Square design for 3 periods of 21 days duration each (9 ewes per treatment, 27 replications). Treatments were TMR (crude protein [CP] = 16.1, total digestible nutrients = 69.1%) moisture levels for 40%, 50%, and 60%.

RESULTS

No differences were found in body weight gain among all treatment groups (p>0.05). Nitrogen balance including digestible N, retained N, and urinary and fecal N showed no change among the treatment groups (p>0.05). Fresh water intake was the lower in 50% TMR moisture group than in the other groups (p<0.05). Other than ether extract which was higher in 60% TMR moisture group (p<0.05) the differences among nutrient digestibilities including CP, organic matter, dry matter, neutral detergent fiber, acid detergent fiber, and non-fiber carbohydrate were not significant (p>0.05). No significant difference was observed for serum protein, blood urea nitrogen, glucose, and triglyceride among the treatment groups (p>0.05). Wool and blood cortisol were not different among the treatment groups (p>0.05). Blood hematology including red blood cell, white blood cells, hemoglobin, hematocrit, basophils, and eosinophils were not different among the treatment groups (p>0.05).

CONCLUSION

It is concluded that TMR moisture at 40%, 50%, and 60% had no effects on N balance parameters, and nutrient digestibilities except for the ether extract under hot and humid conditions. Additionally there were no effects on stress conditions include wool cortisol, as well as blood cortisol levels of ewes.

Effects of clay after a grain challenge on milk composition and on ruminal, blood, and fecal pH in Holstein cows

Oral supplementation of clay has been reported to function as buffer in dairy cows. However, its effects on rumen, blood, and fecal pH have varied among studies. Our objective was to determine the effects of 3 concentrations of dietary clay supplementation after a grain challenge. Ten multiparous rumen-cannulated Holstein cows [body weight (mean ± standard deviation)=648±12kg] with 142±130 (60 to 502) days in milk were assigned to 1 of 5 treatments in a replicated 5×5 Latin square design balanced to measure carryover effects. Periods (21d) were divided into an adaptation phase (d 1 to 18, with regular total mixed ration fed ad libitum) and a measurement phase (d 19 to 21). Feed was restricted on d 18 to 75% of the average of the total mixed ration fed from d 15 to 17 (dry matter basis), and on d 19 cows received a grain challenge. The challenge consisted of 20% finely ground wheat administered into the rumen via a rumen cannula, based on the average dry matter intake obtained on d 15 to 17. Treatments were POS (no clay plus a grain challenge), 3different concentrations of clay (0.5, 1, or 2% of dietary dry matter intake), and control (C; no clay and no grain challenge). Statistical analysis was performed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Contrasts 1 (POS vs. C) and 2 (POS vs. the average of 0.5, 1, or 2%) were compared, along with linear and quadratic treatment effects. Rumen, fecal, and blood pH, along with blood metabolites, were measured at 0, 4, 8, 12, 16, 20, 24, 36, and 48h relative to the grain challenge. Cows fed POS had lower rumen pH [(mean ± standard error) 6.03±0.06] than cows fed C (6.20±0.06). Cow fed POS had lower fecal pH (6.14±0.04) than cows fed C (6.38±0.04). We observed a linear treatment effect for rumen pH and fecal pH. Fecal pH (6.22±0.04) was higher for cows fed clay (contrast 2) then for cows fed POS (6.14±0.04). We also observed a treatment difference (contrast 2) for negative incremental area under the curve, pH below 5.6 × h/d, (0.5% clay=7.93±0.83, 1% clay=8.56±0.83, and 2% clay=7.79±0.83) compared with POS (11.0±0.83). Cows fed clay tended to have higher milk yield (0.5% clay=28.8±3.4kg, 1% clay=30.2±3.4kg, and 2% clay=29.1±3.4kg, contrast 2), and had higher 3.5% fat-corrected milk (0.5% clay=29.9±3.5kg, 1% clay=34.1±3.5kg, and 2% clay=33.1±3.4kg), and higher energy-corrected milk (0.5% clay=29.1±3.3kg, 1% clay=32.8±3.4kg, and 2% clay=31.6±3.3kg) than cows fed POS (27.7±3.4kg, 28.0±3.4kg, 27.7±3.3kg, respectively). In conclusion, cows fed clay had higher rumen pH, energy-corrected milk, fat-corrected milk, and a trend for milk yield than cows fed POS.

Replacing conventional with brown midrib corn silage in a total mixed ration: the impact on early and late lactation dairy cow intake, milk yield and composition, and milk fatty acids profile

Brown midrib corn silage (BMRS) is used as an alternative to conventional corn silage (CS) to increase milk yield because of its higher neutral detergent fibre digestibility (NDFD) and DM intake (DMI). Forty Holstein dairy cows were used in a completely randomised design with a 2 × 2 factorial arrangement. Two groups of 13 cows in early lactation (EL) and 7 in late lactation (LL) were fed with a total mixed ration including brown midrib (BMR) or conventional corn silage (C), for a period of 42 days. The cows were milked twice a day, milk yield and DMI were recorded, and NDFD was estimated. Milk composition was measured twice a week and milk fatty acid profile was quantified on the final week of the experiment. In EL, BMR diet increased DMI, NDFD, milk and protein yield whereas milk fat content and yield were decreased. Concentrations of trans-10 C18:1 and trans-10, cis-12 C18:2 in milk were higher in BMR. In LL cows DMI was similar between BMR and C whereas milk and fat yields tended to be higher in C. Fat-corrected milk yield was greater in the C diet. The effect of the BMRS on DMI and milk yield depended on stage of lactation, justifying its use in early lactation. The lower milk fat concentration, observed when BMRS was included in the diets, could be explained in part by an increased concentration of trans-10 C18:1 and trans-10, cis-12 C18:2.

Metagenomic assessment of the functional potential of the rumen microbiome in Holstein dairy cows

The microbial ecology of the rumen microbiome is influenced by the diet and the physiological status of the dairy cow and can have tremendous influence on the yield and components of milk. There are significant differences in milk yields between first and subsequent lactations of dairy cows, but information on how the rumen microbiome changes as the dairy cow gets older has received little attention. We characterized the rumen microbiome of the dairy cow for phylogeny and functional pathways by lactation group and stage of lactation using a metagenomics approach. Our findings revealed that the rumen microbiome was dominated by Bacteroidetes (70%), Firmicutes (15-20%) and Proteobacteria (7%). The abundance of Firmicutes and Proteobacteria were independently influenced by diet and lactation. Bacteroidetes contributed to a majority of the metabolic functions in first lactation dairy cows while the contribution from Firmicutes and Proteobacteria increased incrementally in second and third lactation dairy cows. We found that nearly 70% of the CAZymes were oligosaccharide breaking enzymes which reflect the higher starch and fermentable sugars in the diet. The results of this study suggest that the rumen microbiome continues to evolve as the dairy cow advances in lactations and these changes may have a significant role in milk production.

Metabolic Disorders in the Transition Period Indicate that the Dairy Cows' Ability to Adapt is Overstressed

Simple Summary

Metabolic disorders are a key problem in the transition period of dairy cows and often appear before the onset of further health problems. Problems derive from difficulties animals have to adapt to large variations and disturbances occurring both outside and inside the organism. A lack of success in solving these issues may be due to predominant approaches in farm management and agricultural science, dealing with such disorders as merely negative side effects. Instead, a successful adaptation of animals to their living conditions should be seen as an important end in itself. Both farm management and agricultural sciences should support animals in their ability to cope with nutritional and metabolic challenges by employing a functional and result-driven approach.

Abstract

Metabolic disorders are a key problem in the transition period of dairy cows and often appear before the onset of further health problems. They mainly derive from difficulties the animals have in adapting to changes and disturbances occurring both outside and inside the organisms and due to varying gaps between nutrient supply and demand. Adaptation is a functional and target-oriented process involving the whole organism and thus cannot be narrowed down to single factors. Most problems which challenge the organisms can be solved in a number of different ways. To understand the mechanisms of adaptation, the interconnectedness of variables and the nutrient flow within a metabolic network need to be considered. Metabolic disorders indicate an overstressed ability to balance input, partitioning and output variables. Dairy cows will more easily succeed in adapting and in avoiding dysfunctional processes in the transition period when the gap between nutrient and energy demands and their supply is restricted. Dairy farms vary widely in relation to the living conditions of the animals. The complexity of nutritional and metabolic processes and their large variations on various scales contradict any attempts to predict the outcome of animals’ adaptation in a farm specific situation. Any attempts to reduce the prevalence of metabolic disorders and associated production diseases should rely on continuous and comprehensive monitoring with appropriate indicators on the farm level. Furthermore, low levels of disorders and diseases should be seen as a further significant goal which carries weight in addition to productivity goals. In the long run, low disease levels can only be expected when farmers realize that they can gain a competitive advantage over competitors with higher levels of disease.

Lactobacillus mixtipabuli sp. nov. isolated from total mixed ration silage

Using a polyphasic taxonomic approach, we investigated three bacterial strains – IWT30T, IWT8 and IWT75 – isolated from total mixed ration silage prepared in Hachimantai, Iwate, Japan. The isolates comprised Gram-stain positive, non-motile, non-spore-forming, catalase-negative, rod-shaped bacteria. Good growth occurred at 15–45 °C and at pH 4.0–7.5. Their major cellular fatty acids were C18:1ω9c and C19:1 cyclo 9,10.The G+C content of genomic DNA of strain IWT30T was 44.6 mol%. Comparative 16S rRNA gene sequence analysis showed that these novel strains belonged to the genus Lactobacillus. These strains shared 100 % 16S rRNA gene sequence similarity and were most closely related to the type strains of Lactobacillus silagei, Lactobacillus odoratitofui, Lactobacillus similis, Lactobacillus collinoides, Lactobacillus paracollinoides and Lactobacillus kimchicus, with sequence similarity values of 99.5, 98.8, 98.7, 97.8, 97.8 and 96.8 %, respectively. The level of DNA–DNA relatedness between these strains and their closest phylogenetic neighbours was less than 30 %. On the basis of additional phylogenetic analysis of pheS and rpoA gene sequences and phenotypic and chemotaxonomic characteristics, we conclude that these three strains represent a novel species of the genus Lactobacillus, for which we propose the name Lactobacillus mixtipabuli sp. nov. The type strain is IWT30T ( = JCM 19805T = DSM 28580T).

Occurrence of pre- and post-harvest mycotoxins and other secondary metabolites in Danish maize silage

Maize silage is a widely used feed product for cattle worldwide, which may be contaminated with mycotoxins, pre- and post-harvest. This concerns both farmers and consumers. To assess the exposure of Danish cattle to mycotoxins from maize silage, 99 samples of whole-crop maize (ensiled and un-ensiled) were analyzed for their contents of 27 mycotoxins and other secondary fungal metabolites by liquid chromatography-tandem mass spectrometry. The method specifically targets the majority of common pre- and post-harvest fungi associated with maize silage in Denmark. Sixty-one samples contained one or more of the 27 analytes in detectable concentrations. The most common mycotoxins were zearalenone, enniatin B nivalenol and andrastin A, found in 34%, 28%, 16% and 15% of the samples, respectively. None of the samples contained mycotoxins above the EU recommended maximum concentrations for Fusarium toxins in cereal-based roughage. Thus, the present study does not indicate that Danish maize silage in general is a cause of acute single mycotoxin intoxications in cattle. However, 31 of the samples contained multiple analytes; two samples as much as seven different fungal metabolites. Feed rations with maize silage may therefore contain complex mixtures of fungal secondary metabolites with unknown biological activity. This emphasizes the need for a thorough examination of the effects of chronic exposure and possible synergistic effects.

Relationship of severity of subacute ruminal acidosis to rumen fermentation, chewing activities, sorting behavior, and milk production in lactating dairy cows fed a high-grain diet

The objectives of the current study were to evaluate the variation in severity of subacute ruminal acidosis (SARA) among lactating dairy cows fed a high-grain diet and to determine factors characterizing animals that are tolerant to high-grain diets. Sixteen ruminally cannulated late-lactating dairy cows (days in milk=282 ± 33.8; body weight=601 ± 75.9 kg) were fed a high-grain diet consisting of 35% forage and 65% concentrate mix. After 17 d of diet adaptation, chewing activities were monitored for a 24-h period and ruminal pH was measured every 30s for 72 h. Acidosis index, defined as the severity of SARA (area of pH <5.8) divided by dry matter intake (DMI), was determined for individual animals to assess the severity of SARA normalized for a feed intake level. Although all cows were fed the same diet, minimum pH values ranged from 5.16 to 6.04, and the acidosis index ranged from 0.0 to 10.9 pH · min/kg of DMI. Six cows with the lowest acidosis index (0.04 ± 0.61 pH · min/kg) and 4 with the highest acidosis index (7.67 ± 0.75 pH · min/kg) were classified as animals that were tolerant and susceptible to the high-grain diet, respectively. Total volatile fatty acid concentration and volatile fatty acid profile were not different between the groups. Susceptible animals sorted against long particles, whereas tolerant animals did not (sorting index=87.6 vs. 97.9, respectively). However, the tolerant cows had shorter total chewing time (35.8 vs. 45.1 min/kg of DMI). In addition, although DMI, milk yield, and milk component yields did not differ between the groups, milk urea nitrogen concentration was higher for tolerant cows compared with susceptible cows (12.8 vs. 8.6 mg/dL), which is possibly attributed to less organic matter fermentation in the rumen of tolerant cows. These results suggest that a substantial variation exists in the severity of SARA among lactating dairy cows fed the same high-grain diet, and that cows tolerant to the high-grain diet might be characterized by less sorting behavior but less chewing time, and higher milk urea nitrogen concentration.