Feeding Lactose to Increase Ruminal Butyrate and the Metabolic Status of Transition Dairy Cows

Effects of sucrose and lactose as partial replacement to corn in lactating dairy cow diets. A review

Carbohydrates are one of the three macronutrients that provides energy in diets and are classified by their structures. Starch is a nonstructural carbohydrate and polysaccharide made of glucose monomers used for storage in plant cells. When starch makes up greater than 30% of the DM in diets there can be adverse effects on NDF digestibility due to decreases in ruminal pH. Sugars are water soluble carbohydrates that consist of monosaccharide and disaccharide units. Sugars ferment faster than starch because microorganisms in the rumen can ferment carbohydrates at different rates depending on their structure; however, this has not been shown to have negative effects on the ruminal pH. Sources of sugars such as molasses (sucrose) or whey (lactose) can be included in the diet as a partial replacement for starch in dairy cow diets. The purpose of replacing starch with sugars in a diet would be to add differing sources of carbohydrates in the diet to allow for continual fermentation of carbohydrates by the microorganisms in the rumen. It has been seen in studies and previous literature that the partial replacement of starch with sugars has the potential to maintain the ruminal environment and milk yield and composition in dairy cows without reducing NDF digestibility. The objective of this review is to evaluate the effects of partially replacing starch with sugars in dairy diets and its implication on ruminal fermentation, nutrient utilization, milk production, and feeding replacement strategy.

Effects of partially replacing dietary corn with molasses, condensed whey permeate, or treated condensed whey permeate on ruminal microbial fermentation

Corn is a feedstuff commonly fed to dairy cows as a source of energy. The objective of this study was to evaluate whether partially replacing dietary corn with molasses or condensed whey permeate, in lactating dairy cow diets in a dual-flow continuous culture system, can maintain nutrient digestibility by ruminal microorganisms. Furthermore, this study evaluated whether treating condensed whey permeate before feeding could aid the fermentation of the condensed whey permeate in the rumen. Eight fermentors were used in a 4 × 4 replicated Latin square with 4 periods of 10 d each. The control diet (CON) was formulated with corn grain, and the other diets were formulated by replacing corn grain with either sugarcane molasses (MOL), condensed whey permeate (CWP), or treated condensed whey permeate (TCWP). Diets were formulated by replacing 4% of the diet dry matter (DM) in the form of starch from corn with sugars from the byproducts. Sugars were defined as water-soluble carbohydrates (WSC) in the rations. The fermentors were fed 52 g of DM twice daily of diets containing 17% crude protein, 28% neutral detergent fiber, and 45% nonfiber carbohydrates. Liquid treatments were pipetted into each fermentor. After 7 d of adaptation, samples were collected for analyses of volatile fatty acids (VFA), lactate, and ammonia, and fermentors' pH were measured at time points after the morning feeding for 3 d. Pooled samples from effluent containers were collected for similar analyses, nutrient flow, and N metabolism. Data were statistically analyzed using Proc MIXED of SAS version 9.4 (SAS Institute Inc.); fixed effects included treatment and time, and random effects included fermentor, period, and square. The interaction of treatment and time was included for the kinetics samples. The TCWP and MOL treatments maintained greater fermentor pH compared with CWP. Total VFA concentration was increased in CWP compared with MOL. The acetate:propionate ratio was increased in TCWP compared with CON, due to tendencies of increased acetate molar proportion and decreased propionate molar proportion in TCWP. Lactate concentration was increased in MOL. Digestibility of WSC was increased in the diets that replaced corn with byproducts. The partial replacement of 4% of DM from corn starch with the sugars in byproducts had minimal effects on ruminal microbial fermentation and increased pH. Treated CWP had similar effects to molasses.

Rumen Development of Artificially-Reared Lambs Exposed to Three Different Rearing Regimens

The objective of this study was to examine the effect of three different rearing regimens on rumen development in lambs reared artificially. Romney ram lambs were randomly allocated to one of three treatments: commercial milk replacer fed to 57 d of age and high fibre concentrate pellets (HFP57); commercial milk replacer, high fibre concentrate pellets, and early weaning from milk replacer at 42 d of age (HFP42); high protein milk replacer from 2-16 d of age followed by commercial milk replacer, low fibre concentrate pellets, and early weaning from milk replacer at 42 d of age (LFP42). Lambs were slaughtered at 57 d of age. Volatile fatty acid content in rumen fluid at slaughter was analysed and rumen tissue samples were collected for histological examination. The rumen n-butyric content was greater (p < 0.05) in both LFP42 and HFP42 treatment lambs compared to HFP57 lambs. The n-valeric content was greater (p < 0.05) in LFP42 lambs compared to both HFP57 and HFP42 treatment lambs. Thickness of the rumen dorsal wall determined by ultrasound scanning at 49 d was greater (p < 0.05) in both HFP42 and LFP42 lambs compared to HFP57 lambs. There was an interaction (p < 0.05) between treatment and site of rumen tissue sampling on papillae width, density, and rumen muscular layer thickness. Collectively, early weaning and the provision of a low fibre pellet leads to improved rumen function and physical development.

Offering soybean molasses adsorbed to agricultural by-products improved lactation performance through modulating plasma metabolic enzyme pool of lactating cows

BACKGROUND

Agricultural by-products, such as corncob powder (CRP), wheat bran (WB), rice husk (RH), defatted bran (DB), and soybean hulls (SH), were widely used as ruminant feed. However, the combination effect of soybean molasses mixed with agricultural by-products on cow lactating performance remains poorly understood.

METHODS

In vitro fermentation simulation technique was used to select the high ruminal fermentation performance of agricultural by-products mixed with soybean molasses. The selected mixtures were conducted to further explore the feeding effect on milk performance and blood metabolic enzyme on lactating dairy cows.

RESULTS

In in vitro simulation, it was confirmed that SH-SM showed better fermentation performance (including higher maximum gas production, acetate, propionate, and total VFA, but less initial fractional rate of degradation) than other four molasses-adsorbents, while WB-SM had the greatest DM and NDF disappearance and NH3-N and butyrate concentrations among substrates. After the simulation selection, we performed the feed experiment with SH-SM and WB-SM compared to the control. For lactating performance, higher (p < .01) milk fat and total milk solid content were observed in WB-SM, and a tendency improvement of milk protein content (p < .01) was observed in both of the cows fed with WB-SM and SH-SM. Among lactating periods, the blood glutamic-pyruvic transaminase, α-amylase, and lactate dehydrogenase which associated with amino acid metabolism and carbohydrate metabolism were improved in lactating dairy cows fed with WB-SM and SH-SM.

CONCLUSION

Dietary agricultural by-products (like wheat bran and soybean hulls) mixed with soybean molasses enhance the lactating performance of dairy cows by improving the host metabolism process of amino acids and carbohydrates. The mixed strategy for agricultural by-products shows another strong evidence for the resource reuse on dairy industry and reducing the by-product pollution.

Rumen microbiota and its relation to fermentation in lactose-fed calves

In our previous studies, we revealed the effect of lactose inclusion in calf starters on the growth performance and gut development of calves. We conducted the present study as a follow-up study to identify the shift in rumen microbiota and its relation to rumen fermentation when calves are fed a lactose-containing starter. Thirty Holstein bull calves were divided into 2 calf starter treatment groups: texturized calf starter (i.e., control; n = 15) or calf starter in which starch was replaced with lactose at 10% (i.e., LAC10; n = 15) on a dry matter basis. All calves were fed their respective treatment calf starter ad libitum from d 7, and kleingrass hay from d 35. Rumen digesta were collected on d 80 (i.e., 3 wk after weaning) and used to analyze rumen microbiota and fermentation products. There was no apparent effect of lactose feeding on the α-diversity and overall composition of rumen microbiota. Amplicon sequencing and real-time PCR quantification of the 16S rRNA gene confirmed that the abundance of butyrate-producing bacteria (i.e., Butyrivibrio group and Megasphaera elsdenii) did not differ between the control and LAC10 groups. Conversely, the relative abundance of Mitsuokella spp., which produce lactate, succinate, and acetate, was significantly higher in the rumen of calves that were fed lactose, whereas the lactate concentration did not differ between the control and LAC10 groups. These findings suggest that the lactate production can be elevated by an increase of Mitsuokella spp. and then converted into butyrate, not propionate, since the proportion of propionate was lower in lactose-fed calves. In addition, we observed a higher abundance of Coriobacteriaceae and Pseudoramibacter-Eubacterium in the LAC10 group. Both these bacterial taxa include acetate-producing bacteria, and a positive correlation between the acetate-to-propionate ratio and the abundance of Pseudoramibacter-Eubacterium was observed. Therefore, the higher abundance of Coriobacteriaceae, Mitsuokella spp., and Pseudoramibacter-Eubacterium in the rumen of lactose-fed calves partially explains the increase in the proportion of rumen acetate that was observed in our previous study.

Lactose: Use, measurement, and expression of results

Lactose has different uses in the dairy, food, and pharmaceutical industries. Being aware of the different forms of lactose and their concentrations can be very helpful in managing dairy product quality, properties, and manufacturing efficiency. Correct measurement and reporting of lactose concentration in milk and other dairy products will be of increased importance in the future as more value-added uses of lactose are developed and as milk lactose data are used in farm management decision making. Lactose should be reported as anhydrous lactose because lactose data will be used to make increasingly important decisions in dairy processing, dairy product labeling, and milk production in the future. Lactose also plays an important role in milk synthesis within a cow. Milk production factors and dairy cattle breed selection influence the amount of high value fat and protein produced per unit of lactose. If the off-farm value of lactose remains low, more attention may be focused on using ultrafiltration to process milk and leave 50 to 60% of the lactose and water from milk at the farm to recover the energy value of the lactose as feed and reduce the hauling cost of the high value components of milk to a dairy product manufacturing factory. Many methods exist to determine lactose concentration, but the most important methods are enzymatic assays, HPLC, and mid-infrared analysis. New, value-added uses for lactose need to be developed. Consistent and accurate methods of lactose measurement and consistent expression of lactose results will support this development process. Starting in January 2017, the USDA Federal Milk Market Laboratories began reporting lactose content of milk as anhydrous lactose and discontinued the reporting of lactose by difference.

A Review Regarding the Use of Molasses in Animal Nutrition

Simple Summary

The aim of the authors is to make a summary of the possible applications of molasses in animal nutrition, how to improve hays and silage qualities for beef and dairy cattle; to enhance industrial byproducts values by liquid feed in swine production; and to improve with feed blocks the extensive livestock production efficiency (cows, buffaloes, sheep, goats and pigs). Focus is both on characteristics feed based on molasses and on ruminal fermentation: the techniques of production, conservation and administration to animals have been widely described as being capable of positively influencing animal performance, milk and meat quality, as well as animal welfare.

Abstract

In the past fifty years, agriculture, and particularly livestock production, has become more resource-intensive, with negative implications regarding world environmental status. Currently, the circular economy 3R principles (to reduce, reuse and recycle materials) can offer many opportunities for the agri-food industry to become more resource-efficient. The closed-loop agri-food supply chain has the great potential of reducing environmental and economic costs, which result from food waste disposal. To meet these principles, the use of crop byproducts, such as molasses, in animal nutrition improves the nutritive value of coarse and poorly desired feedstuff, which could present a real opportunity. The aims of this study were to summarize the possible applications of molasses for animal nutrition, to improve hay and silage quality for beef and dairy cattle, to enhance industrial byproduct values using liquid feed in swine production, and to improve extensive livestock production with feed blocks. The study focused on both feed characteristics, based on molasses, and on ruminal fermentation of its carbohydrates; the techniques of the production, conservation and administration of molasses to animals have been widely described as being capable of positively influencing animal performance, milk and meat quality.

Symposium review: Big data, big predictions: Utilizing milk Fourier-transform infrared and genomics to improve hyperketonemia management

Negative animal health and performance outcomes are associated with disease incidences that can be labor-intensive, costly, and cumbersome for many farms. Amelioration of unfavorable outcomes through early detection and treatment of disease has emphasized the value of improving health monitoring. Although the value is recognized, detecting hyperketonemia (HYK) is still difficult for many farms to do practically and efficiently. Increasing data streams available to farms presents opportunities to use data to better monitor cow and herd health; however, challenges remain with regard to validating, integrating, and interpreting data. During the transition to lactation period, useful data are presented in the form of milk production and composition, milk Fourier-transform infrared (FTIR) wavelength absorbance, cow management records, and genomics, which have been employed to monitor postpartum onset of HYK. Attempts to predict postpartum HYK from test-day milk and performance variables incorporated into multiple linear regression models have demonstrated sufficient accuracy to monitor monthly herd prevalence; however, they lacked the sensitivity and specificity for individual cow diagnostics. Subsequent artificial neural network prediction models employing FTIR data and milk composition variables achieved 83 and 81% sensitivity and specificity for individual cow diagnostics. Although these results fail to reach the diagnostic goals of 90%, they are achieved without individual cow blood samples, which may justify acceptance of lower performance. The caveat is that these models depend on milk analysis, which is traditionally done every 4 weeks. This infrequent sampling allows for a single diagnostic sample for about half of the fresh cows. Benefits to farms are greatly improved if postpartum cows can be milk-tested weekly. Additionally, this allows for close monitoring of somatic cell count and may open the door for use of other herd health monitoring tools. Future improvements in these models may be achievable by maximizing sensitivity at the expense of specificity and may be most economical in disorders for which the cost of treatment is less than that of mistreating (e.g., HYK). Genomic predictions for HYK may be improved by incorporating genome-wide associated SNP and further utilized for precision management of HYK risk groups. Development and validation of HYK prediction models may provide producers with individual cow and herd-level management tools.

Nitrogen utilization, whole-body urea-nitrogen kinetics, omasal nutrient flow, and production performance in dairy cows fed lactose as a partial replacement for barley starch

The objective of this study was to determine whether the partial replacement of barley starch with lactose (fed as dried whey permeate; DWP) affects N utilization, whole-body urea kinetics, and production in dairy cows. Eight lactating Holstein cows were used in a replicated 4 × 4 Latin square design with 28-d periods. Four cows in one Latin square were ruminally cannulated and used to determine dietary effects on whole-body urea kinetics and N utilization. Cows were fed a barley-based diet that contained 3.6% (dry matter basis) total sugar (TSG; designated control), or diets that contained 6.6, 9.6, or 12.6% TSG. Dietary TSG content was increased by the replacement of barley grain with DWP (83% lactose). Diets were isonitrogenous (∼17.3% crude protein), and starch contents of the control, 6.6, 9.6, and 12.6% TSG diets were 24.3, 22.2, 21.2, and 19.1%, respectively. Whole-body urea kinetics were measured using 4-d infusions of [¹⁵N¹⁵N]-urea with concurrent total collections of feces and urine. Dry matter intake (mean = 26.7 kg/d), milk yield (mean = 34.9 kg/d), and milk protein and fat contents were unaffected by diet. Ruminal ammonia-N concentration decreased linearly as TSG content increased, whereas ruminal butyrate concentration increased linearly as TSG content increased. Urinary excretion of total N and urea-N changed quadratically, whereas urinary excretion of total N (% of N intake) tended to change quadratically as TSG content increased. Fecal N excretion linearly increased as TSG content increased. A quadratic response was observed for total N excretion as TSG content increased. Milk N and retained N were not affected by diet. As TSG content increased, we observed quadratic responses in the omasal flow of fluid-associated and total bacterial nonammonia N, endogenous production of urea-N, urea-N recycled to the gastrointestinal tract, and urea-N returned to the ornithine cycle. Dietary TSG content did not affect the anabolic utilization of recycled urea-N or the proportion of recycled urea-N that was used for bacterial growth. Our results indicate that feeding DWP did not influence dry matter intake, milk yield, or milk composition. Feeding DWP decreased ruminal ammonia-N concentration, but this did not result in positive responses in milk protein secretion or N balance. The quadratic response in omasal flow of total bacterial nonammonia N indicated that including TSG beyond 9.6% of diet dry matter might depress ruminal microbial protein synthesis.

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.

Effect of adding different levels of rumen protected choline to the diet on productive and reproductive performance of female goats and growth of their kids from birthing to weaning

Forty female goats in the third parity were randomly divided into four similar groups. The experiment was started 20 days before mating and lasted until the end of the suckling period for 60 days and weaning their kids. The first group were fed diet without supplementation and kept as control while in the second, third and fourth groups, each doe was fed diets with rumen protected choline (RPC) at the rate of 10, 20 and 40 g/day, respectively. Results showed that number of doe kidding twins and triplets and litter weight of kids born per group increased with increasing the level of RPC in the diet of goats and viability rate of born kids during the suckling period improved due to RPC supplementation in the diets of their mothers. Duration of estrous, days from weaning to estrous, days from kidding to estrous and kidding interval decreased significantly, while conception rate increased due to adding RPC. Milk choline concentrations and total choline secretion though milk were progressively increased significantly with increasing the level of RPC supplementation. Live body weight and daily body gain of their suckling male and female kids at weaning increased significantly with increasing RPC levels in the diets of their mothers.

Effects of partial replacement of dietary starch from barley or corn with lactose on ruminal function, short-chain fatty acid absorption, nitrogen utilization, and production performance of dairy cows

In cows fed diets based on corn-alfalfa silage, replacing starch with sugar improves milk production. Although the rate of ruminal fermentation of sugar is more rapid than that of starch, evidence has been found that feeding sugar as a partial replacement for starch does not negatively affect ruminal pH despite increasing diet fermentability. The mechanism(s) for this desirable response are unknown. Our objective was to determine the effects of replacing barley or corn starch with lactose (as dried whey permeate; DWP) on ruminal function, short-chain fatty acid (SCFA) absorption, and nitrogen (N) utilization in dairy cows. Eight lactating cows were used in a replicated 4 × 4 Latin square design with 28-d periods and source of starch (barley vs. corn) and level of DWP (0 vs. 6%, DM basis) as treatment factors. Four cows in 1 Latin square were ruminally cannulated for the measurement of ruminal function, SCFA absorption, and N utilization. Dry matter intake and milk and milk component yields did not differ with diet. The dietary addition of DWP tended to increase ruminal butyrate concentration (13.6 vs. 12.2 mmol/L), and increased the Cl(-)-competitive absorption rates for acetate and propionate. There was no sugar effect on minimum ruminal pH, and the duration and area when ruminal pH was below 5.8. Minimum ruminal pH tended to be lower in cows fed barley compared with those fed corn (5.47 vs. 5.61). The duration when ruminal pH was below pH 5.8 tended to be shorter (186 vs. 235 min/d), whereas the area (pH × min/d) that pH was below 5.8 was smaller (47 vs. 111) on the corn than barley diets. Cows fed the high- compared with the low-sugar diet had lower ruminal NH3-N concentration. Feeding the high-sugar diet tended to increase apparent total-tract digestibility of dry matter and organic matters and increased apparent total-tract digestibility of fat. Apparent total-tract digestibility of N tended to be greater in cows fed barley compared with those fed corn, whereas apparent total-tract digestibility of acid-digestible fiber was greater in cows fed corn compared with those fed barley. In conclusion, partially replacing dietary corn or barley starch with sugar upregulated ruminal acetate and propionate absorption, suggesting that the mechanisms for the attenuation of ruminal acidosis when sugar is fed is partly mediated via increased SCFA absorption.

Microbial butyrate and its role for barrier function in the gastrointestinal tract

Butyrate production in the large intestine and ruminant forestomach depends on bacterial butyryl-CoA/acetate-CoA transferase activity and is highest when fermentable fiber and nonstructural carbohydrates are balanced. Gastrointestinal epithelia seem to use butyrate and butyrate-induced endocrine signals to adapt proliferation, apoptosis, and differentiation to the growth of the bacterial community. Butyrate has a potential clinical application in the treatment of inflammatory bowel disease (IBD; ulcerative colitis). Via inhibited release of tumor necrosis factor α and interleukin 13 and inhibition of histone deacetylase, butyrate may contribute to the restoration of the tight junction barrier in IBD by affecting the expression of claudin-2, occludin, cingulin, and zonula occludens poteins (ZO-1, ZO-2). Further evaluation of the molecular events that link butyrate to an improved tight junction structure will allow for the elucidation of the cofactors affecting the reliability of butyrate as a clinical treatment tool.

Dietary molasses increases ruminal pH and enhances ruminal biohydrogenation during milk fat depression

Feeding high-concentrate diets has the potential to cause milk fat depression, but several studies have suggested that dietary sugar can increase milk fat yield. Two experiments were conducted to evaluate the ability of dietary molasses to prevent milk fat depression in the presence of a 65% concentrate diet. In trial 1, molasses replaced corn grain at 0, 2.5, or 5% of diet dry matter in diets fed to 12 second-lactation Holstein cows (134±37 d in milk) in a 3×3 Latin square design. Trial 1 demonstrated that replacing up to 5% of dietary dry matter from corn with molasses had positive effects on de novo fatty acid synthesis, increasing the yield of short- and medium-chain fatty acids during diet-induced milk fat depression. Increasing inclusion rate of molasses increased milk fat concentration, but decreased milk yield and milk protein yield. Trial 2 used 7 ruminally cannulated, multiparous, late-lactation Holstein cows (220±18 d in milk) to evaluate effects of dietary molasses on ruminal parameters and milk composition, and also to assess whether increased metabolizable protein supply would alter these responses. Cows were randomly assigned to a dietary treatment sequence in a crossover split plot design with 0 and 5% molasses diets. Dietary treatments were fed for 28 d, with 16 d for diet adaptation, and the final 12 d for 2 abomasal infusion periods in a crossover arrangement. Abomasal infusions of water or AA (5 g of l-Met/d+15 g of l-Lys-HCl/d+5 g of l-His-HCl-H(2)O/d) were administered 3 times daily for 5 d, with 2 d between infusion periods. Administration of AA had no effect on concentration or yield of any milk components. Addition of molasses increased milk fat concentration (2.71 vs. 2.94±0.21%), but had no effect on yields of milk fat or protein. Dietary molasses decreased total volatile fatty acid concentration (141 vs. 133±4.6mM), decreased the molar proportion of propionate, and increased the molar proportion of butyrate in ruminal fluid. Molasses also increased ruminal pH (5.73 vs. 5.87±0.06), decreased the yield of trans-10 C18:1, and increased the yield of trans-11 C18:1 in milk fat. These data provide evidence that molasses may promote mammary de novo fatty acid synthesis in cows fed high-energy rations by moderating ruminal pH and altering ruminal fatty acid biohydrogenation pathways.

Corn grain and liquid feed as nonfiber carbohydrate sources in diets for lactating dairy cows

Interactions of sources and processing methods for nonstructural carbohydrates may affect the efficiency of animal production. Five rumen-cannulated cows in late lactation were placed in a 5 × 5 Latin square design and fed experimental diets for 2 wk. In the production trial, 54 cows were fed the experimental diets for 12 wk beginning at d 60 in milk. Diets contained 24% corn silage and 22% hay, averaging 20% alfalfa and 2% grass but being adjusted as needed to maintain dietary concentrations of 36% neutral detergent fiber. The control diet contained steam-flaked corn (SFC) and the other diets contained either finely (FGC; 0.8 mm) or coarsely ground corn (CGC; 1.9 mm), factorialized with or without 3.5% liquid feed (LF). The LF diets provided 1.03% of dietary dry matter as supplemental sugar. The FGC decreased rumen pH and concentration of NH(3)N compared with CGC. The SFC and FGC tended to increase the molar percentage of ruminal propionate and decrease the acetate:propionate ratio. The LF increased molar percentage of ruminal butyrate with FGC but not CGC. The LF tended to decrease starch digestibility with the CGC but not with the FGC. As expected, the SFC and FGC increased total tract starch digestibility. The DMI and milk yield were similar among dietary treatments. Compared with ground corn diets, the SFC tended to decrease milk fat percentage; thus, 3.5% fat-corrected milk and feed efficiency were decreased with SFC. The LF decreased milk protein percentage but had no effect on milk protein yield. The SFC compared with dry ground corn decreased the concentration of milk urea nitrogen. Sugar supplementation using LF appeared to be more beneficial with FGC than CGC. Increasing the surface area by finely grinding corn is important for starch digestibility and optimal utilization of nutrients.

Effects of feeding salt-tolerant forage cultivated in saline-alkaline land on rumen fermentation, feed digestibility and nitrogen balance in lamb

BACKGROUND

Mixing salt-tolerant plants with other plants may affect rumen fermentation, which could result in an increase of feed conversion rate. The objective of this study was to evaluate the effects of partially or entirely replacing the corn stover with a mixture of salt-tolerant forage (Dahurian wildrye grass, weeping alkaligrass and erect milkvetch) in the diet of lambs on ruminal fermentation, feed digestibility and nitrogen (N) balance. Ratios of corn stover to the mixture of salt-tolerant forages in the four experimental diets were 100:0, 67:33, 33:67 and 0:100, respectively, for control, low (LF), medium (MF) and high (HF).

RESULTS

Ruminal pH was lower (P = 0.048) with LF and MF than with control and HF diets. Total VFA concentration was consistently higher (P = 0.039) for LF and MF than for control and HF with increasing amount of salt-tolerant forage. Ratio of acetate to propionate was linearly (P = 0.019) decreased due to the decrease in acetate production. Digestibilities of OM, NDF and CP in the whole tract linearly (P < 0.002) decreased with increasing amount of salt-tolerant forage. Similarly, retained N and ratio of retained N to digestible N also linearly (P < 0.005) decreased.

CONCLUSION

Feeding salt-tolerant forage cultivated in saline-alkaline land improved rumen fermentation with increased total VFA production, and changed the rumen fermentation pattern to increased butyrate production. However, the decreased feed digestibility in the whole digestive tract of lamb may reduce nutrient availability to animals and thus adversely affect animal productivity. Additionally, feeding salt-tolerant forages may require more protein supplement to meet animal requirements, because of the low protein content and low protein digestibility of the salt-tolerant forages.

Effect of rumen-protected choline and methionine on physiological and metabolic disorders and reproductive indices of dairy cows

The objective of this study was to investigate the effect of feeding different levels of ruminally protected methionine and choline on the incidence of physiological and metabolic disorders, production, and some of the reproductive indices of Holstein dairy cows. Forty Holstein dairy cows in their first and second lactation were used from 4-week pre-partum through 20-week post-partum and randomly assigned to receive one of the following treatments: 18 g/day of rumen-protected methionine (RPM), 60 g/day of rumen-protected choline (RPC), 18 g/day of RPM + 60 g/day of RPC, and neither supplement (control). The treatments significantly affected services per conception and open days of lactating dairy cows (p < 0.05), but did not affect significantly on days to first oestrus and number of pregnant cows. RPM + RPC-fed cows had the lowest open days, days to first oestrus and services per conception compared with other groups. The effect of treatments was significant on the incidence of metabolic and physiological problems except for foot/leg problems. Cows fed RPM+RPC had the lowest health problems compared with other groups (p < 0.05). Results indicate that the supplementation of RPM and RPC can improve reproductive performance and health status of dairy cows.

Review: Effects of feeding sugars on productivity of lactating dairy cows

Oba, M. 2011. Review: Effects of feeding sugars on productivity of lactating dairy cows. Can. J. Anim. Sci. 91: 37–46. Sugars are water-soluble carbohydrates that are readily available in the rumen. Although sugars ferment faster than starch or fibre in the rumen, the rates of disaccharide hydrolysis and monosaccharide fermentation vary greatly depending on the type of sugar and rumen environment. Despite rapid fermentation in the rumen and their potential to provide greater fermentable energy to enhance microbial protein production, feeding sugars in place of dietary starch sources may not decrease rumen pH or improve N utilization efficiency and milk protein production in dairy cows. However, feeding high-sugar diets often increases dry matter intake, butyrate concentration in the rumen, and milk fat yield. These nutritional characteristics of sugars may allow us to use high-sugar feedstuffs as an alternative energy source for lactating dairy cows to increase dietary energy density with reduced risk of rumen acidosis, but there is little evidence in the literature to indicate that the synchrony of rumen fermentation would be enhanced by feeding high-sugar diets with high soluble protein. Greater butyrate production from feeding high-sugar diets is expected to enhance proliferation of gut tissues, but its physiological mechanisms and effects of butyrate metabolism on overall productivity of dairy cows warrant further investigations.

Interaction of molasses and monensin in alfalfa hay- or corn silage-based diets on rumen fermentation, total tract digestibility, and milk production by Holstein cows

Sugar supplementation can stimulate rumen microbial growth and possibly fiber digestibility; however, excess ruminal carbohydrate availability relative to rumen-degradable protein (RDP) can promote energy spilling by microbes, decrease rumen pH, or depress fiber digestibility. Both RDP supply and rumen pH might be altered by forage source and monensin. Therefore, the objective of this study was to evaluate interactions of a sugar source (molasses) with monensin and 2 forage sources on rumen fermentation, total tract digestibility, and production and fatty acid composition of milk. Seven ruminally cannulated lactating Holstein cows were used in a 5 x 7 incomplete Latin square design with five 28-d periods. Four corn silage diets consisted of 1) control (C), 2) 2.6% molasses (M), 3) 2.6% molasses plus 0.45% urea (MU), or 4) 2.6% molasses plus 0.45% urea plus monensin sodium (Rumensin, at the intermediate dosage from the label, 16 g/909 kg of dry matter; MUR). Three chopped alfalfa hay diets consisted of 1) control (C), 2) 2.6% molasses (M), or 3) 2.6% molasses plus Rumensin (MR). Urea was added to corn silage diets to provide RDP comparable to alfalfa hay diets with no urea. Corn silage C and M diets were balanced to have 16.2% crude protein; and the remaining diets, 17.2% crude protein. Dry matter intake was not affected by treatment, but there was a trend for lower milk production in alfalfa hay diets compared with corn silage diets. Despite increased total volatile fatty acid and acetate concentrations in the rumen, total tract organic matter digestibility was lower for alfalfa hay-fed cows. Rumensin did not affect volatile fatty acid concentrations but decreased milk fat from 3.22 to 2.72% in corn silage diets but less in alfalfa hay diets. Medium-chain milk fatty acids (% of total fat) were lower for alfalfa hay compared with corn silage diets, and short-chain milk fatty acids tended to decrease when Rumensin was added. In whole rumen contents, concentrations of trans-10, cis-12 C(18:2) were increased when cows were fed corn silage diets. Rumensin had no effect on conjugated linoleic acid isomers in either milk or rumen contents but tended to increase the concentration of trans-10 C(18:1) in rumen samples. Molasses with urea increased ruminal NH(3)-N and milk urea N when cows were fed corn silage diets (6.8 vs. 11.3 and 7.6 vs. 12.0 mg/dL for M vs. MU, respectively). Based on ruminal fermentation characteristics and fatty acid isomers in milk, molasses did not appear to promote ruminal acidosis or milk fat depression. However, combinations of Rumensin with corn silage-based diets already containing molasses and with a relatively high nonfiber carbohydrate:forage neutral detergent fiber ratio influenced biohydrogenation characteristics that are indicators of increased risk for milk fat depression.

Efficacy of liquid feeds varying in concentration and composition of fat, nonprotein nitrogen, and nonfiber carbohydrates for lactating dairy cows

In trial 1, we evaluated the efficacy of a liquid feed (LF) containing cane molasses and corn steep liquor as carriers of suspended white grease (WG) without or with urea (U) or with soybean lipid (SL; a byproduct of soybean processing) compared with roasted soybeans plus tallow blended into respective concentrates in a 16-wk lactation study. The dry matter intake (DMI) and milk production for LF diets were either similar to or greater than respective controls, although SL decreased milk fat percentage. In trial 2, we compared LF without fat to LF plus WG or SL and also evaluated the dose response to increasing amount of LF + WG in a 16-wk lactation trial in which the LF products were added to respective total mixed rations. The DMI was increased and then decreased (quadratic response) with increasing LF + WG without a linear response. However, production of milk, protein, and fat increased linearly with corresponding quadratic responses, which we interpret to be a result of a limiting returns response from DMI and density of net energy for lactation. When LF plus SL was fed, milk fat percentage and yield decreased compared with the comparable amount of LF + WG. In a 12-wk lactation study (trial 3), we added 3.25 or 6.5% of the dry matter as LF (a different but generally similar product than the previous trials and without fat) to diets formulated to maintain comparable ruminal nonstructural carbohydrate digestibility by adding soybean hulls to decrease nonfiber carbohydrates (NFC) concentration; the 6.5% LF diet was without or with Rumensin (11.5 g/909 kg of dry matter). When 3.25% LF was added but NFC was decreased from 40 to 37%, cows increased DMI and production of milk fat. Adding Rumensin decreased DMI but maintained milk fat yield compared with its 6.25% LF control without Rumensin. In trials 1 and 3, apparent total tract nutrient digestibility was not affected by treatment. In conclusion, feeding LF at about 5% (trial 2, which contained WG, 1.6% added sugar) or 3.25% (trial 3, 1.7% added sugar) generally increased DMI and maintained or increased production of milk, protein, and fat.

Slow-Release Urea and Highly Fermentable Sugars in Diets Fed to Lactating Dairy Cows

This experiment was designed to test the inclusion of highly fermentable sugars (FS) in dairy rations and their interactions with a slow-release urea (SU) product. The FS are a blend of liquid coproducts from the corn milling and cheese industries, and the SU is calcium chloride urea. Eight multiparous and 4 primiparous Brown Swiss cows (117 +/- 46 d in milk) were blocked by parity and utilized in a multiple Latin square design. Basal diets were formulated for 16.6% crude protein and 1.55 Mcal/kg of net energy for lactation and contained 35% of dietary dry matter as corn silage, 15% alfalfa hay, 34% of a concentrate mix containing varying proportions of ground shelled corn and soybean meal, and 16% of a constant concentrate premix. The premix consisted of equal proportions of corn distillers grains, soybean hulls, expeller soybean meal, vitamins, and minerals across all diets. Diets contained either no supplemental FS (NFS) or FS (8.64% RationMate) and either no SU (NSU) or SU (0.61% Ruma Pro) in a 2 x 2 factorial arrangement of treatments. Feeding FS tended to decrease milk production compared with feeding NFS. Milk fat percentage was increased for cows fed FS compared with NFS. Feeding SU decreased dry matter intake and increased feed efficiency compared with cows fed NSU. Dietary treatment had no effect on energy-corrected milk, milk fat yield, milk protein percentage, or milk urea N. Feeding FS increased the molar proportion of ruminal butyrate and decreased the molar proportion of propionate; however, no other effects were observed on ruminal fermentation. No interactions between FS and SU were observed. It was concluded that the replacement of corn and soybean meal with dietary FS increased milk fat percentage and that the replacement of soybean meal with SU significantly improved feed efficiency.