Total Mixed Ration Samples Research Articles

Physicochemical properties of whole milk powder derived from cows fed pasture or total mixed ration diets

This study examined the effect of dietary factors on compositional and functional properties of whole milk powder (WMP) produced from bovine milk. Raw milk samples were obtained from 3 groups of 18 Holstein Friesian spring-calving cows randomly assigned to diets based on perennial ryegrass (GRS), perennial ryegrass/white clover sward (CLV), and total mixed ration (TMR). Raw milks obtained in late lactation were subsequently standardized for fat, heat-treated (90°C for 30 s), evaporated, and homogenized before spray drying. The WMP produced from each diet were analyzed to determine differences in color, particle size distribution, heat coagulation time, yogurt gelation, texture profile, and protein profile due to each diet. Significant differences in heat coagulation time were observed between the CLV and TMR samples, whereas color values were significantly different between GRS and TMR samples. No significant differences in gross composition, protein profile, or whey protein nitrogen index were found between the 3 WMP samples. Average D90 values (the particle size at which 90% of the particles were smaller than the specified size) for fat globules were significantly lower in the TMR sample compared with the GRS and CLV samples. Yogurts produced from GRS- and CLV-derived WMP had significantly higher elastic moduli (G') than those produced from TMR-derived WMP. Similarly, texture profile analysis revealed significantly higher firmness values in yogurt samples derived from CLV compared with TMR samples. Our data characterize the effect of these diets on the composition and functional properties of fat-standardized WMP, suggesting better yogurt functionality and thermal stability in WMP derived from pasture-based bovine diets.

Protein value of diets for dairy cows with different proportions of crude protein originating from red clover silage versus soybean meal

The objective of this study was to evaluate the effect of replacing crude protein (CP) of soybean meal (SBM) with red clover silage (RCS) in total mixed rations (TMR) on ruminally undegraded feed CP (RUP) and intestinal digestibility (ID) of RUP. Four TMR were formulated to replace CP from SBM with RCS. The TMR was comprised of forage and concentrates (0.75:0.25), with ratios of RCS in TMR of 0.15, 0.30, 0.45, and 0.60 on a dry matter (DM) basis. The ruminal degradation of CP was determined using the nylon bag technique. For this, samples of TMR were incubated for 2, 8, 16, 24, 32 and 72 h. The RUP content of TMR was estimated using passage rates of 2, 5 and 8%/h. Additionally, samples of TMR were incubated in the rumen for 16 h, and their feed residues were used for determination of ID of RUP using the mobile-bag technique. For in situ ruminal degradation, increasing RCS and reducing SBM proportions increased linearly the rapidly degradable CP (a) from 26.2 to 212 g/kg CP (P < 0.001). The potentially degradable CP (b) decreased linearly from 810 to 676 g/kg CP (P < 0.001). Assuming a passage rate of 8%/h, RUP reduced linearly from 315 to 253 g/kg CP (P < 0.001). The ID of RUP reduced linearly from 760 to 574 g/kg CP (P < 0.001) with increasing RCS levels. Although differences in ruminal CP degradation and ID of RUP were apparently caused by differences in the proportion of RCS and SBM, neither linear nor quadratic effects on total tract digestible CP were observed (P = 0.22 and 0.21, respectively), and averaged 943 g/kg CP among all TMR tested. This suggests that increasing RCS and decreasing SBM proportion shifted the site of CP utilization. The CP degraded in the rumen increased, and the amount of intestinally absorbable RUP reduced linearly from 184 to 79 g/kg CP (P < 0.001). In general, replacing CP from SBM with RCS in the TMR reduced its protein value. It is concluded, that an almost complete replacement of CP from SBM by RCS in rations of high-yielding dairy cows cannot be recommended. However a replacement rate up to 0.30 does not lead to a substantial reduction in RUP supply and digestibility, and therefore considerably reduces the use of SBM.

Risk factors associated with beef cattle losses on intensive fattening farms in Austria, Germany and Italy

The aim of this study was to investigate management and feeding practices associated with on-farm loss rate (mortality) on 63 beef cattle farms in Austria, Germany and Italy with housing systems other than fully slatted pens. Information on mortality and 56 categorised factors relating to the cleanliness of animal facilities, health and feeding management, animal-human interaction, cattle transport and origin were gathered during on-farm visits. Samples of total mixed rations (TMRs) were collected and analysed for chemical composition and particle size distribution. Twenty-eight categorised factors were removed from the initial 56 due to exclusion criteria (missing data≥20% and/or monolevel factors with≥80% answers in one category). Mortality was the response variable in the risk factor analysis and the remaining 10 continuous covariates from TMR analyses and 28 categorised factors were independent predictors. Mean (±standard deviation) mortality, representing the proportion of dead, euthanased and early culled animals over the total number of animals bought in or reared in the previous year, was 2.8±3.5%. Fourteen factors were significantly associated with mortality in the bivariable analyses; seven factors were not considered further in the multivariable analysis due to collinearity. None of the factors related to TMR were associated with mortality. Four categorical factors, referring to biosecurity measures and management, were retained in the final multivariable model, with country effect. Buying cattle from only one farm, no mixing of animals during transport, presence of a dedicated sick pen and keeping production records were associated with lower percentage mortality.

Chemical homogeneity and particle size distribution of dairy cow TMR along the feeding alley with different mixing times

Following the concepts of precision feeding, the right components balance (Sova et al., 2014) and the correct particle size distribution (PSD, Khan et al., 2014) of total mixed ration (TMR) are essential for a complete homogeneity of the diet and are strongly influenced by adopted mixing time (MT, Humer et al., 2018, Schingoethe et al.,2017). The aim of the trial was to determine the influence of two MTs (MT1≤7min and MT2>7min) on the chemical homogeneity and PSD along the feeding alley. Diets were performed with a horizontal cutter-mixer wagon (Gulliver 4016, Sgariboldi), and TMR samples were collected from the beginning, middle and end of the feeding alley after discharge. Triplicate samples of the diet were collected for chemical composition analyses (moisture, CP, Ash, EE, NDF and ADF) and PSD evaluation (Heinrichs and Kononoff, 2002) over two months (two sampling/week). Statistical analysis was performed by a PROC MIXED for repeated measurements of SAS. MT1 evidenced a non-uniform distribution of moisture content along the feeding alley (P=0.05): lower moisture was found at the end than at the beginning and in the middle (47.55 vs 51.13 and 51.00%, respectively; P<0.01). No significant effects of MTs were recorded for other chemical parameters. The PSD showed trend to a higher retained amount of fibre in MT1 upper sieve (14.79 vs. 10.14%; P=0.06), while lower amount of feed was found in middle and bottom sieve than MT2 (38.9 and 12.81 vs 42.17 and 14.32%, respectively; P=0.08 and P=0.06). With respect to TMR distribution along the feeding alley, no differences were found between MT1 and MT2. Day of sampling evidenced significant variation both in chemical and physical composition (P<0.05). Obtained preliminary data evidenced the influence of MTs on composition and on PSD of the provided diet; results suggest to daily measure moisture of raw material in order to avoid negative changes in dry matter intake.

Use of a live yeast strain of Saccharomyces cerevisiae in a high-concentrate diet fed to finishing Charolais bulls: effects on growth, slaughter performance, behavior, and rumen environment

Aim of this study was to evaluate effects on growth, slaughter performance, behavior, and rumen environment parameters of dietary supplementation with a live yeast strain of Saccharomyces cerevisiae in a high-concentrate finishing diet fed to young Charolais bulls. A total 171 bulls (initial body weight (BW) = 442 ± 22.8 kg) were stratified by BW and assigned to one of two experimental groups: Control (85 bulls) and Yeast (86 bulls). Each group was allotted to 6 contiguous pens. All bulls were fed the same finishing diet ad libitum as a total mixed ration (TMR) at 0900 h. The live yeast strain of Saccharomyces cerevisiae CNCM I-1077 was added to the Yeast bull premix to target a daily dose of 5 g/bull. Bull final BW (743 ± 18.7 kg) and average daily gain (1.64 ± 0.12 kg) did not differ between groups. However, yeast increased dry matter (DM) intake (11.0 versus 10.4 kg/d; P = 0.04) and tended to reduce (P = 0.08) the number of days required for finishing. The effect of yeast on DM intake was particularly relevant in the first weeks of fattening, possibly as a sign of better adaptation by bulls to the high-energy concentration of the finishing diet. Carcass weights and dressing did not differ between treatments, but the likelihood of producing a carcass graded as excellent by conformation score was 2.15 times higher for Yeast than Control bulls (Chi-Square = 14.7 and 95% confidence interval = 1.42–3.27; P < 0.001). Observation of bull behavior assessed during the 8 h after TMR delivery at the end of the 2nd and 4th mo of fattening showed a similar eating and ruminating pattern between treatments. However, yeast provision prevented from the drop in rumination rate (min/kg DM) recorded in Control bulls from the 2nd to the 4th mo of fattening. Physical and chemical analysis of TMR samples collected from the mangers at determined intervals after TMR delivery indicated that bulls of both treatments preferentially selected towards long fibrous particles. Rumen pH, lactic acid and total volatile fatty acid concentrations in samples collected before TMR feeding after the 3rd month of fattening were not affected by treatment but yeast increased acetate and butyrate concentrations as well as acetate:propionate ratio. Post mortem inspection of rumen wall showed that the occurrence of rumen papillae hyperkeratinization was lower for Yeast than Control bulls (relative risk = 0.51 and 95% confidence interval = 0.27–0.95; P = 0.02).

The relationship between shelter management and fattening cattle welfare

The aim of this study was to investigate management and feeding practices associated with on-farm loss rate (mortality) on 63 beef cattle farms in Austria, Germany and Italy with housing systems other than fully slatted pens. Information on mortality and 56 categorised factors relating to the cleanliness of animal facilities, health and feeding management, animal-human interaction, cattle transport and origin were gathered during on-farm visits. Samples of total mixed rations (TMRs) were collected and analysed for chemical composition and particle size distribution. Twenty-eight categorised factors were removed from the initial 56 due to exclusion criteria (missing data ≥ 20% and/or monolevel factors with ≥ 80% answers in one category). Mortality was the response variable in the risk factor analysis and the remaining 10 continuous covariates from TMR analyses and 28 categorised factors were independent predictors. Mean (± standard deviation) mortality, representing the proportion of dead, euthanased and early culled animals over the total number of animals bought in or reared in the previous year, was 2.8 ± 3.5%. Fourteen factors were significantly associated with mortality in the bivariable analyses; seven factors were not considered further in the multivariable analysis due to collinearity. None of the factors related to TMR were associated with mortality. Four categorical factors, referring to biosecurity measures and management, were retained in the final multivariable model, with country effect. Buying cattle from only one farm, no mixing of animals during transport, presence of a dedicated sick pen and keeping production records were associated with lower percentage mortality.

Effect of post-ethanol extraction sorghum silage as a forage source in growing and finishing diets on steer performance, carcass characteristics, and nutrient digestibility.

Two experiments evaluated the use of post-ethanol extraction sorghum silage as an alternative forage source in feedlot diets. Seventy-two crossbred steers (397 kg [SD 23]) were used to evaluate growth and carcass characteristics. Steers were blocked by BW into pens of 6 steers and randomly assigned to growing diets containing 40% (DM basis) sorghum silage (SS; 57.6% NDF) or grass hay (CON; 63.3% NDF) for 56 d ( = 6 pens per treatment). Within each treatment, steers transitioned to dry-rolled corn-based finishing diets (fed for 56 d) containing 6% effective NDF contributed by the forage source, resulting in forage inclusions of 16% for SS and 13.1% for CON, where forage replaced corn. A subsample of steers ( = 12 per treatment) housed in pens equipped with GrowSafe bunks were used for determination of growing phase diet total tract digestibility. From d 28 to 42, steers received titanium dioxide at approximately 10 g∙steer∙d, and fecal samples were collected on d 41 and 42. Fecal and total mixed ration samples were dried and ground for analysis of DM, OM, NDF, ADF, CP, ether extract (EE), and starch. Data were analyzed with the MIXED procedure of SAS, with fixed effects of treatment and block for performance and carcass data or treatment for digestibility data; significance was determined at ≤ 0.05 and tendencies at ≤ 0.10. Growing phase DMI and ADG did not differ due to treatment ( ≥ 0.19); however, SS-fed steers had improved G:F compared with CON-fed steers ( = 0.04). Finishing period ADG and G:F did not differ ( ≥ 0.15) between treatments, despite SS-fed steers having lesser ( = 0.008) DMI than CON-fed steers. No differences in DMI, ADG, or G:F over the whole trial were noted between treatments ( ≥ 0.12) nor were any carcass traits affected ( ≥ 0.23). During the digestibility assessment period, DMI was less ( = 0.003) in SS-fed steers. Growing phase total tract apparent digestibility of DM and starch did not differ ( ≥ 0.19) due to treatment; however, OM digestibility tended to be greater ( = 0.09) in SS-fed steers. Steers fed SS had greater ( ≤ 0.03) digestibility of EE, CP, NDF, and hemicellulose than CON-fed steers. However, CON-fed steers had greater ( < 0.0001) ADF digestibility than SS-fed steers. These data suggest that postextraction sorghum silage can be effectively used in feedlot diets as an alternative forage source.

Prediction of metabolisable energy content of commercial total mixed rations (TMR) for lactating dairy cows based on gas production measured into two TMR fractions

The aim was to estimate the ME content of TMR samples for lactating dairy cows based on 24h gas production (GP) measured in two TMR fractions obtained by sieving that were considered proxy representations of their forage and concentrate contents. Samples of TMR for lactating cows, collected at 15 Italian dairy farms, were dried and fractionated using an apparatus composed of four sieves (mesh diam. of 6.00, 2.36, 1.18, 0.60mm) and a bottom pan. The particles retained by the 6.00, 2.36 and 1.18mm sieves were bulked to create a fraction named “Long” (L), while particles retained by the 0.60mm sieve and the bottom pan created a fraction named “Fine”(F). Samples of whole TMR and of F and L fractions were fermented in rumen fluid (220mg of dried sample into graduated 100ml glass syringes with 30ml of diluted rumen fluid) to measure GP at 0, 1, 2, 4, 6, 8, 12, 24, 48 and 72h of incubation, and GP at 24h was used in multiple equations to predict the ME content. The L fraction was the main part of the TMR (633±61.7g/kg DM) and contained more aNDFom (391 vs 185g/kg DM; P<0.01), less starch (213 vs 394g/kg DM; P<0.01) and less CP (132 vs 181g/kg DM; P<0.01) than the F fraction. The 24h GP measured on the F fraction was 17% higher (P<0.01) than in the L fraction lending to a 25% increase in the predicted ME content of the F fraction (12.1 vs 9.7MJ/kg DM, P<0.01). When the GP of the two fractions were summed on the basis of their relative weights in each TMR to obtain a calculated GP of the whole TMR, this did not differ from that directly measured on the original TMR sample. The ME values of the TMR had substantial variability among samples and the highest ME values measured for the F and L fractions were 13.23 and 10.82MJ/kg DM, respectively. The inclusion of these F and L fraction values in TMR samples that had the lowest ME concentrations (e.g. 10.0–10.4MJ/kg DM), as an hypothetical consequence of an improvement in nutritive quality of the dietary feed components, resulted in a calculated ME increment of about 0.5–0.6 and 0.8–1.0MJ/kg DM, respectively. These simulations suggest appreciable ME variations in cases of substituting nutritionally extreme forages and/or concentrates with corresponding feeds of different nutritive quality.

1622 Evaluation of in vitro and in situ starch digestibility assays

The objective of this experiment was to evaluate commercial in vitro and in situ starch digestibility assays to estimate ruminal starch digestibility (RSD) and rate of ruminal starch degradation (kd). Twelve commercial dairy herds located in Wisconsin, Pennsylvania, and Missouri were used (4 free-stall and 8 tie-stall housing). Fecal samples were collected from 5 high- and 5 low-producing cows from each herd, and samples of total mixed rations (TMR) were collected after feed delivery from each pen (n = 8) or directly in front of each cow (n = 80). Corn silage (CS; n = 13) and corn (dry, n = 9, and high-moisture, n = 7) samples were also collected from each farm. Feed samples were thoroughly mixed and split for analysis. Fecal and TMR samples were sent to Rock River lab for starch analysis. Total tract starch digestibility (TTSD) was calculated from TMR and fecal starch content. The following equation was used to estimate RSD from TTSD: y = 82.224 + (0.185 × ruminal), in which y = TTSD (Ferraretto et al., 2013). Samples of TMR, corn, and CS were sent to Rock River for 7-h in situ starch digestibility and to Dairyland lab for analysis of nutrient composition and 7-h in vitro starch digestibility. All herds tested milk through Dairy Herd Improvement Association and individual milk yield, milk fat, and milk protein content data were collected from test day closest to day of sample collection. The REG procedure of SAS was used to determine the relationship between in situ, in vitro, and in vivo RSD. In situ starch digestibility was related to in vivo RSD (R2 = 0.19, P < 0.002). There was no relationship between in vitro and in vivo RSD (R2 = 0.01, P = 0.45). The Cornell Net Carbohydrate and Protein System (CNCPS) uses ruminal starch kd to predict microbial protein production. Actual milk yield was related to model-predicted milk yield using model default kd for RSD (R2 = 0.69, P < 0.0001). Ruminal starch kd was calculated for CS and corn using in situ data and entered into the CNCPS model (version 6.5; AMTS, LLC). This relationship was improved when measured in situ starch kd was entered for corn and CS (R2 = 0.76, P < 0.0001). In conclusion, in situ starch digestibility at 7 h is a good approach for estimating RSD in vivo and using kd from this method improves milk yield predictions from the CNCPS model.

1418 Effects of post-ethanol extraction sorghum silage as an alternative forage in growing and finishing diets on steer performance, carcass characteristic and nutrient digestibility

Two experiments evaluated use of post-ethanol extraction sorghum silage as an alternative forage to hay in feedlot diets. In experiment one (Exp1), 72 crossbred steers (397 ± 23, SD) were used to evaluate growth and carcass characteristics. Steers were blocked by BW into pens of 6 steers and randomly assigned to growing diets containing 40% (DM basis) of sorghum silage (SS; 57.6% NDF) or grass hay (CON; 63.3% NDF) for 56d (n = 6 pens per treatment). Within each treatment steers transitioned to dry-rolled corn-based finishing diets (fed for 56d) containing 6% effective NDF contributed by the forage source, resulting in forage inclusions of 16% for SS and 13.1% for CON. Experiment two (Exp2), utilized a subsample of steers (n = 12 per treatment) housed in pens equipped with Growsafe bunks for determination of growing phase diet total tract digestibility. From d28- 42, steers received titanium dioxide at approximately 10 g−1·steer−1·d−1. Fecal samples were collected on d 41 and 42. Fecal and total mixed ration samples were dried, and ground for analysis of DM, OM, NDF, ADF, CP, ether extract (EE), and starch. Data were analyzed using PROC MIXED of SAS with the fixed effects of treatment and block (Exp1) or treatment (Exp2); significance was determined at P ≤ 0.05 and tendencies at P ≤ 0.10. Growing phase DMI and ADG did not differ due to treatment (P ≥ 0.19); however, SS-fed steers had improved G:F compared to CON (P = 0.04). Finishing period ADG or G:F did not differ (P ≥ 0.15), despite SS-fed steers having lesser (P = 0.008) DMI than CON-fed steers. No differences in DMI, ADG, or G:F over the whole trial were noted between treatments (P ≥ 0.12), nor were any carcass traits affected (P ≥ 0.23). Growing phase total tract apparent digestibility of DM and starch did not differ (P ≥ 0.19), due to treatment; however, OM digestibility tended to be greater (P = 0.09) in SS-fed steers. During the digestibility assessment period DMI was lesser (P = 0.003) in SS-fed steers. Steers fed the SS diet had greater (P ≤ 0.03) digestibility of EE, CP, NDF, hemicellulose, and cellulose than CON-fed steers. Interestingly, CON-fed steers had greater (P < 0.0001) ADF digestibility than SS-fed steers. These data suggest that post-extraction sorghum silage can be effectively utilized in feedlot diets as an alternative forage.

Management, nutrition, and lactation performance are related to bulk tank milk de novo fatty acid concentration on northeastern US dairy farms

This study investigated the relationship of management practices, dietary characteristics, milk composition, and lactation performance with de novo fatty acid (FA) concentration in bulk tank milk from commercial dairy farms with Holstein, Jersey, and mixed-breed cows. It was hypothesized that farms with higher de novo milk FA concentrations would more commonly use management and nutrition practices known to optimize ruminal conditions that enhance de novo synthesis of milk FA. Farms (n=44) located in Vermont and northeastern New York were selected based on a history of high de novo (HDN; 26.18±0.94g/100g of FA; mean ± standard deviation) or low de novo (LDN; 24.19±1.22g/100g of FA) FA in bulk tank milk. Management practices were assessed during one visit to each farm in March or April, 2014. Total mixed ration samples were collected and analyzed for chemical composition using near infrared spectroscopy. We found no differences in days in milk at the farm level. Yield of milk fat, true protein, and de novo FA per cow per day were higher for HDN versus LDN farms. The HDN farms had lower freestall stocking density (cows/stall) than LDN farms. Additionally, tiestall feeding frequency was higher for HDN than LDN farms. No differences between HDN and LDN farms were detected for dietary dry matter, crude protein, neutral detergent fiber, starch, or percentage of forage in the diet. However, dietary ether extract was lower for HDN than LDN farms. This research indicates that overcrowded freestalls, reduced feeding frequency, and greater dietary ether extract content are associated with lower de novo FA synthesis and reduced milk fat and true protein yields on commercial dairy farms.

Importance of on-farm management practices on lactate-fermenting Clostridium spp. spore contamination of total mixed ration of Manchega ewe feeding. Determination of risk factors and characterization of Clostridium population

This work studies the on-farm management practices that increase the risk of developing high lactate-fermenting Clostridium spp. spore counts in Total Mixed Ration (TMR) of Manchega sheep. Moreover the ecology of the Clostridium population was studied in relation to those management practices. A total of 136 TMR samples belonging of 23 Manchega sheep flocks were analyzed for lactate-fermenting Clostridium spores by the Most Probable Number technique (MPN). Information about the feeding characteristics was also collected from the 23 flocks. A logistic regression analysis indicated silages and wet breweŕs grains used for feeding as the on-farm management risk factors that lead to an increase of Clostridium spp. spore counts. A total of 155 Clostridium isolates from TMR samples were typed using Randomly Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR). The 56 different genotypes obtained were subsequently identified by restriction analysis of 16S-rRNA gene (16S-ARDRA), so three populations were observed: 92.90%, 5.81% and 1.29% corresponding to Clostridium (C.) sporogenes, Clostridium beijerinkii and Clostridium butyricum respectively. The risks factors of high Clostridium spp. spore counts also increased Clostridium population diversity and favoured the presence of C. butyricum. The results confirmed that these risk factors should be taken into account in developing strategies in the control of Clostridium spp. spores contamination in TMR.

Evaluation of Physically Effective Fiber for Distributing Total Mixed Rations in Korea

This study was carried out to evaluate the physical characteristics of total mixed rations (TMR) prepared in Korea for improving productive effectiveness of dairy and beef cattle. The 40 samples of commercial TMR for dairy and beef cattle in 6 municipals were collected and analyzed for chemical composition and physical properties. There were significant regional differences (p<0.05) in dry matter and crude protein contents of TMR for dairy and beef cattle. In roughage value index (RVI), neutral detergent fiber (NDF) content, and physically effective NDF (peNDF)<TEX>$_{1.18}$</TEX> content, there were no regional differences in TMR for dairy cattle, but there were significant regional differences (p<0.05) in TMR for beef cattle. Thus the results from this study support that because RVI, NDF content, and peNDF content in TMR for dairy and beef cattle exceeded recommended ranges, a little adjustment in TMR for dairy cattle will be necessary to obtain optimal productivity.

Variation in nutrients formulated and nutrients supplied on 5 California dairies

Computer models used in ration formulation assume that nutrients supplied by a ration formulation are the same as the nutrients presented in front of the cow in the final ration. Deviations in nutrients due to feed management effects such as dry matter changes (i.e., rain), loading, mixing, and delivery errors are assumed to not affect delivery of nutrients to the cow and her resulting milk production. To estimate how feed management affects nutrients supplied to the cow and milk production, and determine if nutrients can serve as indexes of feed management practices, weekly total mixed ration samples were collected and analyzed for 4 pens (close-up cows, fresh cows, high-milk-producing, and low-milk-producing cows, if available) for 7 to 12wk on 5 commercial California dairies. Differences among nutrient analyses from these samples and nutrients from the formulated rations were analyzed by PROC MIXED of SAS (SAS Institute Inc., Cary, NC). Milk fat and milk protein percentages did not vary as much [coefficient of variation (CV)=18 to 33%] as milk yield (kg; CV=16 to 47 %) across all dairies and pens. Variability in nutrients delivered were highest for macronutrient fat (CV=22%), lignin (CV=15%), and ash (CV=11%) percentages and micronutrients Fe (mg/kg; CV=48%), Na (%; CV=42%), and Zn (mg/kg; CV=38%) for the milking pens across all dairies. Partitioning of the variability in random effects of nutrients delivered and intraclass correlation coefficients showed that variability in lignin percentage of TMR had the highest correlation with variability in milk yield and milk fat percentage, followed by fat and crude protein percentages. But, variability in ash, fat, and lignin percentages of total mixed ration had the highest correlation with variability in milk protein percentage. Therefore, lignin, fat, and ash may be the best indices of feed management to include effects of variability in nutrients on variability in milk yield, milk fat, and milk protein percentages in ration formulation models.

Short communication: Epidemiology and genotyping of Candida rugosa strains responsible for persistent intramammary infections in dairy cows

The present study was undertaken during an outbreak of clinical and subclinical mastitis in 14 dairy cows caused by Candida rugosa, in which high somatic cell counts were seen and cases did not respond to antibiotic treatment. Intramammary infection cured spontaneously in 10 cows, whereas 4 cows were culled as a result of persistent infections. Repeated sampling of these cows and biomolecular analysis of the isolates showed that the infections were caused by the same genotype, even over a period of 2 lactations. Random amplification of the genome of C. rugosa milk isolates gave 3 different DNA banding patterns (genotypes G1, G2, and G3). Viable cells of C. rugosa were also isolated from various environmental sources and were present in high concentrations in total mixed ration samples, which could be considered the primary source of diffusion of viable yeast cells in the environment, as demonstrated by genotyping. The proven capacity of these microorganisms to survive in the environment of the cow, such as the total mixed ration, bedding, water, and cow skin, and to cause persistent intramammary infections highlights the importance of mycotic spread in dairy herds.

Variability in feed and total mixed ration neutral detergent fiber and crude protein analyses among commercial laboratories

The objective of this study was to assess the variability in amylase-treated neutral detergent fiber (aNDF) and crude protein (CP) analyses of feed and total mixed ration (TMR) samples among feed analysis laboratories. Two TMR were prepared that varied in the dry matter proportion of forage and concentrates: 45% forage (LF-TMR) versus 60% forage (HF-TMR). Replicated TMR and individual feed samples were dried, ground through a 4-mm screen, and sent to 10 commercial and 4 research or development laboratories for aNDF and CP analyses. Laboratories were asked to complete a detailed questionnaire regarding the aNDF procedure used. Variability in aNDF and CP analyses was assessed using univariate statistics and mixed modeling procedures. Significant variability in the aNDF analysis of individual feeds was found among the participating laboratories. The variability was particularly large for low-aNDF feeds such as distillers and barley grains. The variability among laboratories in the aNDF analysis of low-fiber TMR was greater than of high-fiber TMR, with the most likely reason being their greater proportions of grains and protein concentrates and the effect of variation in the aNDF protocols, particularly α-amylase use, on the analysis of these types of feeds. Variability due to the technique used for aNDF analysis was not statistically significant when outlier labs using the filter bag technique were removed; however, laboratories using the filter bag technique tended to produce more variable results than did laboratories using variation of the crucible technique (SE=2.542 vs. 0.930, respectively). Calculated aNDF values for TMR, based on proportions and aNDF analysis of individual feeds, were slightly greater than analyzed aNDF values for TMR. Results from this ringtest emphasize the need for feed analysis laboratories to follow the official aNDF method exactly. Variation within and among laboratories can be reduced by replicating analysis and including reference materials in each analytical run. Results of CP analysis were more consistent among laboratories, and variability in CP analysis of individual feeds or TMR was marginally acceptable.

Technical note: Evaluation of procedures for analyzing ration sorting and rumen digesta particle size in dairy cows

Collecting total mixed ration (TMR) samples throughout the day to measure sorting activity of dairy cows may cause changes to the sorting behavior of cows or may make it more difficult to elucidate effects of sorting on TMR particle size distributions. Also, forage particle size research commonly includes analysis of the solid portion of rumen digesta for particle size distribution after digesta has been squeezed through several layers of cheesecloth. Therefore, the first objective of this experiment was to determine if collecting TMR samples throughout the day affected sorting behavior of cows and resulted in a different particle size distribution than when TMR was not artificially altered during the day. The second objective of this experiment was to determine if squeezing rumen digesta samples through cheesecloth changed particle size distribution when analyzed by a wet sieving technique. It was determined that small, significant differences existed in particle size distribution between the 2 sampling methods of TMR for sorting behavior. These differences were more likely to occur at time points later in the day. This resulted in small changes in sorting indices calculated from these data; sampling and mixing TMR throughout the day reduced the degree of sorting. Squeezing rumen digesta through 4 layers of cheesecloth had no effect on particle size distribution of particles >0.15mm but reduced the amount of rumen fluid-associated dry matter contained in the sample.

근적외선 분광법에 의한 국내 축우용 TMR의 성분추정

The present study was conducted to develop a rapid and accurate method of evaluating chemical composition of total mixed ration (TMR) for dairy cows using near infrared reflectance spectroscopy (NIRS). A total of 253 TMR samples were collected from TMR manufacturers and dairy farms in Korea. Prior to NIR analysis, TMR samples were dried at for 48 hour and then ground to 2 mm size. The samples were scanned at 2 nm interval over the wavelength range of 400-2500 nm on a FOSS-NIR Systems Model 6500. The values obtained by NIR analysis and conventional chemical methods were compared. Generally, the relationship between chemical analysis and NIR analysis was linear: and standard error of calibration (SEC) were 0.701 (SEC 0.407), 0.965 (SEC 0.315), 0.796 (SEC 0.406), 0.889 (SEC 0.987), 0.894 (SEC 0.311), 0.933 (SEC 0.885) and 0.889 (SEC 1.490) for moisture, crude protein, ether extract, crude fiber, crude ash, acid detergent fiber (ADF) and neutral detergent fiber (NDF), respectively. In addition, the standard error of prediction (SEP) value was 0.371, 0.290, 0.321, 0.380, 0.960, 0.859 and 1.446 for moisture, crude protein, ether extract, crude fiber, crude ash, ADF and NDF, respectively. The results of the present study showed that the NIR analysis for unknown TMR samples would be relatively accurate. Use of the developed NIR calibration curve can obtain fast and reliable data on chemical composition of TMR. Collection and analysis of more TMR samples will increase accuracy and precision of NIR analysis to TMR.

Particle size evaluation and its association with feed intake, milk yield and chewing activity in mid-lactation Holstein cows

The objective of this study was to determine the associations among fresh and residual fractions of a total mixed ration (TMR), milk production and ruminating proportion of mid-lactation Holstein cows. During March 2002, daily representative TMR samples were collected at 8:00 a.m. from freshly delivered feed on a Holstein dairy in Florida. A sample of the residual feed (weigh-back) was collected at 7:30 a.m., corresponding to the weigh-back of the previous day. Samples were processed daily within 15 minutes of collection. Feed intake (as-fed), maximum and minimum temperatures of the day and individual milk yield were recorded daily. Each day, four hours after the 8 a.m. feeding (12 noon), numbers of cows ruminating and eating were counted. Particle size was evaluated using the Penn State particle size evaluator with three sieves. Dry matter (DM) content of each fraction was evaluated by using a microwave technique. Regression models for different outcomes were conducted. Models were developed using fractions as-fed and as DM basis. Differences in DM content between coarse and medium size were not statistically significant. For all models, predictors were the same for both as-fed basis and DM basis. For dry matter intake (DMI), the only significant predictor was the minimum daily temperature, with a negative association. No variable was associated with weigh-back coarse fraction. However, when coarse and medium fractions were pooled as one fraction, maximum temperature of the day and DMI were predictors of this new outcome. For medium weigh-back fraction, significant predictors were fresh medium fraction proportion and DMI. Dry matter intake was negatively associated with medium fraction proportion. The proportion of cows ruminating was positively related to the proportion of cows eating four hours after fresh feed was placed on the feed bunk. Milk yield was negatively associated with the medium fresh fraction proportion of the day before.

Changes of particle size distribution and chemical composition of a hay-based ration offered once or twice daily to dairy cows

The objective of this experiment is to evaluate the changes of particle size distribution and chemical composition of the total mixed ration (TMR) based on hay as the main forage component (“dry” TMR) and distributed once (7.00 am) or twice (7.00 am and 1.00 pm) daily to 32 lactating cows. The trial was divided in two periods of 14 days each. Diet (DM=53.7%) was formulated in order to assure the nutritional requirements of cows producing 24 kg/d of milk (crude protein=14.4% DM; NDF=40.9% DM; milk FU=0.88/kg DM) and additional amounts of concentrates were distributed using automatic feeders. Four TMR samples were collected daily (7.00 am, 10.00 am, 1.00 pm, 4.00 pm) for six days during each experiment period for a total number of 48 feed samples. Each feed sample was subjected to the estimation of the particle size distribution using the separator of Pennsylvania State University composed of two sieves (diameters of 19 and 8 mm) and a collector on the bottom, and to the determination of the chemical composition. Changes of all three particle size fractions for TMRs were observed during the day with distributions of the TMR both once and twice daily. With the once daily distribution, the large particles fraction increased linearly (P<0.001) from 19.7 to 23.4, 32.2, and 35.1%, while the finest particle fraction decreased (from 60.1 to 58.3, 50.0, 47.8%). According to particle size changes, the chemical composition varied significantly at the different times of sampling when TMR was distributed once daily. Significant variations of DM were detected for TMR with a linear (P<0.001) increase (from 54.4 to 57.9, 60.7, 61.5%). Considering once TMR distribution, the values of NDF and starch showed an opposite trend with an increase of 6.5 and a decrease of 8.3 points from 7.00 am to 4.00 pm (i.e., 9 hrs after distribution). Correlations were estimated between chemical and physical characteristics of TMRs. NDF content was positively and significantly correlated to the fraction of particles retained by a 19 mm sieve (r=0.42; P<0.001) and negatively correlated with the smaller particles (r=-0.51; P<0.001). In conclusion, when the TMRs are prepared excluding corn/hay silages, twice daily distributions of diet can avoid the selection of large feed by the cows, thereby preserving both a uniform particle size distribution and a steady chemical composition of the diet during the day. However, the cost for the extra time needed for twice daily distribution should be carefully considered.