Outdoor grazing of dairy cows on pasture versus indoor feeding on total mixed ration: Effects on gross composition and mineral content of milk during lactation

The influence of feeding system and lactation period on the gross composition, macroelements (Ca, P, Mg, and Na), and trace elements (Zn, Fe, Cu, Mo, Mn, Se, and Co) of bovine milk was investigated. The feeding systems included outdoor grazing on perennial ryegrass pasture (GRO), outdoor grazing on perennial ryegrass and white clover pasture (GRC), and indoors offered total mixed ration (TMR). Sixty spring-calving Holstein Friesian dairy cows were assigned to 3 herds, each consisting of 20 cows, and balanced with respect to parity, calving date, and pre-experimental milk yield and milk solids yield. The herds were allocated to 1 of the 3 feeding systems from February to November. Milk samples were collected on 10 occasions over the period June 17 to November 26, at 2 or 3 weekly intervals, when cows were on average 119 to 281 d in lactation (DIL). The total lactation period was arbitrarily sub-divided into 2 lactation periods based on DIL, namely mid lactation, June 17 to September 9 when cows were 119 to 203 DIL; and late lactation, September 22 to November 26 when cows were 216 to 281 DIL. With the exception of Mg, Na, Fe, Mo, and Co, all other variables were affected by feeding system. The GRO milk had the highest mean concentrations of total solids, total protein, casein, Ca, and P. The TMR milk had the highest concentrations of lactose, Cu, and Se, and lowest level of total protein. The GRC milk had levels of lactose, Zn, and Cu similar to those of GRO milk, and concentrations of TS, Ca, and P similar to those of TMR milk. Lactation period affected all variables, apart from the concentrations of Fe, Cu, Mn, and Se. On average, the proportion (%) of total Ca, P, Zn, Mn, or Se that sedimented with the casein on high-speed ultracentrifugation at 100,000 × g was ≥60%, whereas that of Na, Mg, or Mo was ≤45% total. The results demonstrate how the gross composition and elemental composition of milk can be affected by different feeding systems.     

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.     

Productive performance and digestive response of dairy cows fed different diets combining a total mixed ration and fresh forage

The purpose of this experiment was to determine the effects of feeding increasing levels of fresh forage (FF) as a proportion of total dry matter intake (DMI) on nutrient intake, rumen digestion, nutrient utilization, and productive performance of total mixed ration (TMR)-fed cows. Twelve dairy cows (90 ± 22 d in milk, 523 ± 88 kg of body weight, 7,908 ± 719 kg of milk production in the previous lactation) were housed in individual tiestalls and assigned to treatments according to a 3 × 3 Latin square design replicated 4 times. Treatments were 100% TMR (T100), 75% TMR plus 25% FF (T75), and 50% TMR plus 50% FF (T50). The experiment lasted 60 d, divided into 3 periods of 20 d each; the first 12 d of each period were used for diet adaptation and the last 8 d for data collection. The TMR (18.1% crude protein, 24.6% acid detergent fiber) and FF (Lolium multiflorum; 15.1% crude protein, 24.1% acid detergent fiber) were prepared and cut daily and offered to each cow individually. The highest DMI was reached in T100 and T75, which was reflected in greater intake of the different nutrients than T50. No differences were detected in the apparent total digestibility of the nutrients, mean ruminal pH, and total volatile fatty acid concentrations among treatments. Cows in T50 resulted in the lowest ruminal N-NH₃ concentration and the lowest microbial N flow to the duodenum. Milk yield was 8.5% higher from cows in T100 and T75 compared with T50, but we observed no differences for milk fat or milk protein yield among treatments. Milk fat of cows fed T50 had 8% more unsaturated fatty acids (FA) than that of cows fed T100, mostly because of a higher content of monounsaturated FA. Additionally, cows in T50 had a higher concentration of linoleic acid, vaccenic acid, and rumenic acid than T100. Meanwhile, the concentration of linoleic acid and vaccenic acid in cows fed T75 was higher than T100. The milk fat of the cows fed T50 and T75 had a lower n-6:n-3 ratio than T100. We concluded that including up to 29% of FF in the total DMI in combination with a TMR did not affect the intake or digestion of nutrients or the productive response in dairy cows and resulted in a higher concentration of desirable FA from a consumer's perspective.     

Grazing of dairy cows on pasture versus indoor feeding on total mixed ration: Effects on low-moisture part-skim Mozzarella cheese yield and quality characteristics in mid and late lactation

This study investigated the effects of 3 dairy cow feeding systems on the composition, yield, and biochemical and physical properties of low-moisture part-skim Mozzarella cheese in mid (ML; May–June) and late (LL; October–November) lactation. Sixty spring-calving cows were assigned to 3 herds, each consisting of 20 cows, and balanced on parity, calving date, and pre-experimental milk yield and milk solids yield. Each herd was allocated to 1 of the following feeding systems: grazing on perennial ryegrass (Lolium perenne L.) pasture (GRO), grazing on perennial ryegrass and white clover (Trifolium repens L.) pasture (GRC), or housed indoors and offered total mixed ration (TMR). Mozzarella cheese was manufactured on 3 separate occasions in ML and 4 in LL in 2016. Feeding system had significant effects on milk composition, cheese yield, the elemental composition of cheese, cheese color (green to red and blue to yellow color coordinates), the extent of flow on heating, and the fluidity of the melted cheese. Compared with TMR milk, GRO and GRC milks had higher concentrations of protein and casein and lower concentrations of I, Cu, and Se, higher cheese-yielding capacity, and produced cheese with lower concentrations of the trace elements I, Cu, and Se and higher yellowness value. Cheese from GRO milk had higher heat-induced flow and fluidity than cheese from TMR milk. These effects were observed over the entire lactation period (ML + LL), but varied somewhat in ML and LL. Feeding system had little, or no, effect on gross composition of the cheese, the proportions of milk protein or fat lost to cheese whey, the texture of the unheated cheese, or the energy required to extend the molten cheese. The differences in color and melt characteristics of cheeses obtained from milks with the different feeding systems may provide a basis for creating points of differentiation suited to different markets.     

Supplementing additional cobalt as cobalt lactate in a high-forage total mixed ration fed to late-lactation dairy cows

Cobalt lactate is a highly soluble ruminal Co source. Prior research evaluating higher Co feeding rates demonstrated increased ruminal fiber digestion. Feeding high-forage (>70%) rations to late-lactation dairy cows to enhance income over feed cost could potentially benefit from higher ruminal-soluble Co inclusion rates to enhance ruminal fiber and nutrient digestibility. Twenty-four late-lactation [238 ± 68.8 d in milk (DIM) and 36.4 ± 5.4 kg/d milk] Holstein dairy cows (10 primiparous and 14 multiparous) were blocked by milk yield, DIM, and parity, and randomly assigned to 1 of 2 treatments. Treatments were (1) control, CoCO₃ total mixed ration (TMR) containing 12.5 mg/cow per day of cobalt (cobalt carbonate), and (2) cobalt lactate (Co-LAC), same CoCO₃ TMR but containing an additional 50 mg/cow per day of Co, via a 1% cobalt lactate product (CoMax, Ralco Inc.). The basal TMR was 70% forage [60% alfalfa baleage and 40% corn silage on a dry matter (DM) basis] and 30% of the respective experimental grain mix on a DM basis. Cows were fed the CoCO₃ TMR during the 7-d covariate period, followed by 4 wk of data collection when CoCO₃ and Co-LAC TMR were fed. Milk production (26.2 and 25.8 kg/d for CoCO₃ and Co-LAC, respectively) and dry matter intake (DMI; 22.9 and 23.1 kg/d) were similar for cows fed both Co treatments. Production of milk fat (1.02 and 1.09 kg/d), milk protein (0.87 and 0.91 kg/d), and lactose (1.17 and 1.26 kg/d) were similar for cows fed both treatments. Body weights (684 and 674 kg) were similar for cows fed both treatments. Rumen ammonia concentrations (15.8 and 12.3 mg/dL) were lower for cows fed Co-LAC compared with cows fed CoCO₃ (15.8 mg/dL). Ruminal molar acetate concentrations (59.5 and 61.1%) were greater for cows fed Co-LAC compared with cows fed CoCO₃. Feeding additional Co as cobalt lactate in the TMR did not enhance lactational performance (milk production, composition, DMI, or body weight changes) when fed a high-forage TMR but altered ruminal fermentation with decreased ruminal ammonia and increased ruminal acetate concentrations.     

Monensin for lactating dairy cows grazing mixed-alfalfa pasture and supplemented with partial mixed ration

The effect of monensin on milk production was evaluated in 58 lactating Holstein cows (48 multiparous; 10 primiparous) grazing a mixed-alfalfa pasture and supplemented with a partial mixed ration in a completely randomized design with repeated measurements. Cows were paired by calving date, lactation number, previous lactation milk production, body weight, and body condition score and were assigned to one of 2 treatments: control or monensin. Cows on the monensin treatment received 2 monensin controlled-release capsules (335 mg/d for 90 d), one 30 d before the expecting calving date and the other 60 d after calving. Short-term (0 to 150 d in milk) and long-term (305-d adjusted lactation) effects of monensin were evaluated. Pasture (measured by difference between pre- and postgrazing pasture mass), supplements, and total dry matter intake did not differ between treatments and averaged 8.7, 14.1, and 22.9 kg/d, respectively. In the short-term, monensin increased milk production (27.7 vs. 26.6 kg/d) and milk protein yield (0.890 vs. 0.860 kg/d); milk fat yield was not affected (0.959 kg/d). Monensin decreased milk fat content (3.51 vs. 3.60%) with no changes in milk protein content (3.25%). In the long term, milk production and milk protein yield were also increased by monensin: 214 and 7 kg, respectively. Monensin reduced the loss of body condition score and increased percentage of pregnancy at first service (44.8 vs. 20.7%). Monensin improves production and reproduction performance of dairy cows grazing a mixed-alfalfa pasture and supplemented with a partial mixed ration.     

The effects of feeding a partial mixed ration plus a top-dress before feeding on milk production and the daily rhythm of feed intake and plasma hormones and metabolites in dairy cows

Total mixed rations (TMR) are commonly fed to dairy cows with a goal of reducing ruminal acidosis, but the daily pattern of feed intake has major implication for rumen fermentation and postabsorptive physiology. Generally there is low feed intake during the overnight period and high intake after feeding and during the afternoon. The objective of this study was to determine if feeding a partial mixed ration (PMR) plus a high starch top-dress before feeding of the PMR would improve production and modify key daily rhythms. The top-dress was fed before feeding as ruminal starch is at a nadir and amylolytic capacity is expected to be low. Ten Holstein cows were used in a crossover design with 14-d periods. Cows were housed in tie stalls with feed tubs and feed weight was recorded every 10 s for observation of feeding behavior. Treatments were a control TMR fed once per day at 0900 h or a partial mixed ration plus a top-dress (PMR+TD). The top-dress was fed at 9.5% of DMI offered at 0800 h and contained steamflaked corn, canola meal, and nonprotein nitrogen. No interaction was observed between treatment and milking time. Milk yield tended to be decreased 1.1 kg and milk fat yield was decreased 70 g/d by PMR+TD. Milk fat preformed fatty acids were decreased and no effect was observed of treatment on trans-10 C18:1 or other indicators of biohydrogenation-induced milk fat depression. No effect was observed of treatment on meal parameters including meal size and number. The PMR+TD increased total-tract neutral detergent fiber (NDF) digestibility by 1.2 percentage points. Treatment changed the daily pattern of fecal NDF and indigestible NDF, indicating changes in rumen function over the day. No effect was observed on plasma glucose, but the amplitude of the daily rhythm of insulin was increased by PMR+TD. The PMR+TD also increased plasma nonesterified fatty acids and decreased blood urea nitrogen across the day. Core body temperature is entrained by the central biological clock and its phase was advanced 42 min and its amplitude slightly increased by PMR+TD. In conclusion, the top-dress appears to have modified the central circadian rhythm and plasma insulin and blood urea nitrogen. This demonstrates that timing of feeding can be used to manage daily rhythms of the dairy cow, although the optimal timing requires further investigation.     

Temporal changes in plasma concentrations of hormones and metabolites in pasture-fed dairy cows during extended lactation

This experiment measured variations in plasma concentrations of metabolic hormones and metabolites in cows undergoing extended lactations of up to 670 d at 2 planes of nutrition. Thirty-seven Holstein-Friesian cows that calved in late winter were selected for varying milk yield and then managed for a lactation of 670 d by delaying breeding until approximately 450 d in milk (DIM). Cows grazed fresh pasture supplemented with pasture silage or hay and crushed wheat or triticale grain. Dietary intake was reduced by approximately 1.8 kg (dry matter) grain/cow per day for 19 of the cows from 300 DIM until the end of lactation to assess the effect of restricted energy intake on the persistency of milk production. Samples of blood were collected monthly from each cow to measure plasma concentrations of selected hormones and metabolites. Dietary restriction beyond 300 DIM reduced yields of milk, protein, and fat, but did not alter the proportion of cows reaching the 670-d lactation target. Dietary restriction had no effect on cow BW or plasma concentrations of any hormones or metabolites. Overall, blood plasma concentrations of insulin-like growth factor-I, leptin, and glucose were elevated from 301 to 600 DIM compared with 0 to 300 DIM, whereas concentrations of growth hormone and nonesterified fatty acids were lower after 300 DIM. Plasma concentrations of insulin and prolactin were unaffected by stage of lactation, but prolactin concentrations increased during summer. These changes were consistent with a decrease in milk yield and an increase in the partitioning of nutrients to body tissue gain, primarily adipose tissue, throughout the later stages of the extended lactation. Cows that continued milking beyond 600 DIM had increased plasma concentrations of growth hormone and decreased concentrations of glucose and leptin compared with cows that milked <600 DIM. These differences, coupled with reduced body weight gain, indicated an increased priority for nutrient partitioning to milk production at the expense of body tissue gain throughout the extended lactation period in cows with greater lactation persistency.     

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 feeding frequency of a total mixed ration on the performance of high-yielding dairy cows

Forty Finnish Ayrshire cows, 16 primiparous and 24 multiparous, were randomly assigned to 1 of 2 treatments (FF1 or FF5). Total mixed ration (TMR) was fed once a day on the FF1 treatment and 5 times a day on the FF5 treatment. The experiment began at calving and continued to wk 28 of lactation. The TMR consisted of a grass silage and concentrate mix. The amount of concentrate in the TMR was 51% on a DM basis. The feeding frequency had no effect on milk or energy-corrected milk yields or on milk composition. The average energy-corrected milk yield was 32.8 kg/d on the FF1 treatment and 32.5 kg/d on the FF5 treatment. The less frequent feeding increased the dry matter intake (DMI) of cows. The average DMI during the experiment was 20.9 kg/d on the FF1 treatment and 19.9 kg/d on the FF5 treatment. The difference in DMI was due to the differences in DMI of the mature cows. Energy and protein conversion tended to be lower with feeding once a day compared with feeding 5 times a day. The cows’ feeding behavior was also observed. Cows fed 5 times a day tended to eat quite evenly after each delivery, whereas on the FF1 treatment there were 2 clear feeding peaks in the evening after the feed delivery. The time spent eating during the observation period was longer on FF5 than on FF1. The cows fed once a day spent more time lying than the cows fed 5 times a day. Based on the observations of feeding behavior, feeding a TMR 5 times a day seemed to be too frequent based on the increased restlessness and decreased lying time of the cows.     

Effects of altering total mixed ration conservation method when feeding dry-rolled versus steam-flaked hulled rice on lactation and digestion in dairy cows

We evaluated the effects of different methods of conserving the total mixed ration (TMR) and processing hulled rice (Oryza sativa L.) on intake, digestion, ruminal fermentation, lactation performance, and nitrogen utilization in dairy cows. Eight multiparous Holstein cows (126 ± 19 d in milk) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of dietary treatments. The experimental diets used fresh TMR and ensiled TMR containing either dry-rolled (DR) hulled rice or steam-flaked (SF) hulled rice. The fresh TMR was prepared every morning. The ensiled TMR was prepared by baling fresh TMR and then sealing it with a bale wrapper; this was stored outdoors at 10 to 30°C for >4 mo. The method of grain processing did not affect the dry matter (DM) intake. The DM intake tended to be greater for ensiled TMR than for fresh TMR. Apparent total-tract DM digestibility and milk yield were increased by feeding ensiled TMR instead of fresh TMR and by replacing DR with SF. An interaction effect between the TMR conservation method and the grain processing method was detected for DM digestibility and milk yield; replacing DR with SF increased the DM digestibility and milk yield in cows fed fresh TMR, but this did not affect the cows fed ensiled TMR. The milk fat and lactose contents did not differ among dietary treatments. The milk protein concentration was higher for the cows fed SF processed hulled rice than those fed DR, but it was not influenced by the TMR conservation method. The ruminal total volatile fatty acid concentration was higher for the cows fed ensiled TMR compared with those fed fresh TMR, but it was not affected by the grain processing method. The molar proportion of acetate was decreased and propionate was increased by feeding ensiled TMR instead of fresh TMR and by replacing DR with SF. The concentrations of rumen ammonia N and plasma urea N were higher for the cows fed ensiled TMR than fresh TMR and were lower for SF than DR. Feeding ensiled TMR instead of fresh TMR increased the cows' urinary N excretion and decreased the retention N. Replacing DR with SF decreased the urinary N excretion, increased the milk N secretion, and then improved the nitrogen efficiency. These results show that feeding ensiled TMR instead of fresh TMR has an adverse effect on N utilization, but it increases digestion and milk production. Replacing DR with SF also increases digestion, milk yield, and milk protein content, and the improvement of milk yield by replacing DR with SF was prominent in the cows fed fresh TMR.     

Ruminal digestion and fermentation of high-producing dairy cows with three different feeding systems combining pasture and total mixed rations

Six multiparous Holstein cows fitted with rumen cannulas were used to study the effect of three feeding systems combining pasture and total mixed rations (TMR) on ruminal digestion in a 21-wk repeated measures experiment. The three treatments were: 1) pasture plus concentrate (PC), 2) pasture plus partial TMR (pTMR), and 3) TMR (nonpasture). Ruminal NH3-N concentration was lower on both the pTMR and TMR treatments (10.2 +/- 0.5 mg/dL) than on the PC treatment (19.9 +/- 0.5 mg/dL). Ruminal pH was not affected by treatments and averaged 5.87. Neither total volatile fatty acid concentration (137.5 mmol/L) nor individual volatile fatty acid proportions (63.1,20.6, and 12.0 mol/ 100 mol for acetate, propionate, and butyrate, respectively) differed among treatments. The pTMR treatment reduced the total potentially degradable fraction of dry matter (85.5 vs. 82.3%) and the potentially digestible fraction of neutral detergent fiber (82.1 vs. 74.9%) of pasture compared to the PC treatment. Ruminal NH3-N losses were reduced when combining pasture and TMR; however this combination decreased the ruminal digestion of pasture, indicating the presence of associative effects in the rumen.     

Effects of a perennial ryegrass diet or total mixed ration diet offered to spring-calving Holstein-Friesian dairy cows on methane emissions, dry matter intake, and milk production

The objective of the present study was to compare the enteric methane (CH₄) emissions and milk production of spring-calving Holstein-Friesian cows offered either a grazed perennial ryegrass diet or a total mixed ration (TMR) diet for 10 wk in early lactation. Forty-eight spring-calving Holstein-Friesian dairy cows were randomly assigned to 1 of 2 nutritional treatments for 10 wk: 1) grass or 2) TMR. The grass group received an allocation of 17 kg of dry matter (DM) of grass per cow per day with a pre-grazing herbage mass of 1,492 kg of DM/ha. The TMR offered per cow per day was composed of maize silage (7.5 kg of DM), concentrate blend (8.6 kg of DM), grass silage (3.5 kg of DM), molasses (0.7 kg of DM), and straw (0.5 kg of DM). Daily CH₄ emissions were determined via the emissions from ruminants using a calibrated tracer technique for 5 consecutive days during wk 4 and 10 of the study. Simultaneously, herbage dry matter intake (DMI) for the grass group was estimated using the n-alkane technique, whereas DMI for the TMR group was recorded using the Griffith Elder feeding system. Cows offered TMR had higher milk yield (29.5 vs. 21.1 kg/d), solids-corrected milk yield (27.7 vs. 20.1 kg/d), fat and protein (FP) yield (2.09 vs. 1.54 kg/d), bodyweight change (0.54 kg of gain/d vs. 0.37 kg of loss/d), and body condition score change (0.36 unit gain vs. 0.33 unit loss) than did the grass group over the course of the 10-wk study. Methane emissions were higher for the TMR group than the grass group (397 vs. 251 g/cow per day). The TMR group also emitted more CH₄ per kg of FP (200 vs. 174 g/kg of FP) than did the grass group. They also emitted more CH₄ per kg of DMI (20.28 vs. 18.06 g/kg of DMI) than did the grass group. In this study, spring-calving cows, consuming a high quality perennial ryegrass diet in the spring, produced less enteric CH₄ emissions per cow, per unit of intake, and per unit of FP than did cows offered a standard TMR diet.     

Effects of providing total mixed rations indoors and on pasture on the behavior of lactating dairy cattle and their preference to be indoors or on pasture

Grazing is considered a normal behavior for dairy cattle, although they may not be able to meet their nutritional requirements from grazing alone, and so to sustain higher yields requires access to a total mixed ration (TMR). The study aim was to provide dairy cows with access to TMR indoors and on pasture to establish influence on behavior and preference for each location. The study took place from August to November, 2009, using 36 late-lactation Holstein-Friesian dairy cows. The cows were allocated to 1 of 3 26-d study periods (n = 12 × 3). Within each period the cows were further divided into a control (n = 6) or treatment (n = 6) group using a crossover design, where the cows were changed between the control and treatment group after 13 d. Treatment cows had access to TMR indoors and on pasture, whereas control cows only had access to TMR indoors. Following a.m. and p.m. milkings the cows were taken to a point equidistant between indoors and pasture and given the choice of going to pasture (1.5 ha) or to a freestall barn. Between milkings the cows had free access between the locations. Initial choice was recorded and a video camera was used to record time spent in each location. Behavior observations were recorded to establish how the cows spent their time during the day. To determine what factors influenced preference, weather conditions, milk yield, body condition score, and lameness were recorded. Initially, the cows chose indoors following milking (96.4 ± 0.80%). Overall, the cows expressed a partial preference for pasture (71.1 ± 1.82%), which was different from 100, 50, and 0%. Study period influenced preference with cows spending less time on pasture as the season progressed (86.7 vs. 68.3 vs. 58.3% for study periods 1, 2, and 3, respectively). Providing the cows with TMR outdoors did not affect pasture use, but resulted in an increase in TMR intake of 2.2 ± 0.41 kg of dry matter/d. The cows spent more time on pasture as the temperature-humidity index indoors (55.6 ± 0.92) and outdoors (54.6 ± 0.82) increased, but rainfall and milk yield did not influence preference. Cows with lameness score >1.5 spent more time indoors (35.4 ± 4.52 vs. 25.2 ± 2.64% for cows with >1.5 vs. ≤1.5 lameness score, respectively). In conclusion, the cows expressed a partial preference for pasture, which was not influenced by providing TMR on pasture.     

Ensiling of soybean curd residue and wet brewers grains with or without other feeds as a total mixed ration

Wet brewers grains and soybean curd residue were stored in laboratory-scale silos without (BG and SC silages, respectively) or with other ingredients as total mixed rations (BGT and SCT silages, respectively). Silages were opened after 14 and 56 d, and microbial counts, fermentation products, and aerobic stability were determined. Denaturing gradient gel electrophoresis was carried out to examine bacterial communities, and several bacteria that appeared to be involved in fermentation were identified. Lactic acid content was greater in SCT than in BGT silage, but lower in SC than in BG silage. Ethanol content was greater in BG than in SC regardless of silage type. Aerobic deterioration occurred promptly in ensiling materials (nonensiled by-products and total mixed ration mixtures) and in silages stored alone; however, SCT and BGT silages resisted deterioration and no heating was found for more than 5.5 d regardless of storage period. Silages were stable even with high yeast populations at silo opening, whereas prolonged ensiling decreased yeast counts in the 2 total mixed ration silages. The denaturing gradient gel electrophoresis profiles appeared similar between SCT and BGT silages but not between SC and BG silages. Weissella spp. and Lactobacillus brevis were common in aerobically stable SCT and BGT silages, and Lactobacillus buchneri was detected only in BGT silage. Both L. brevis and L. buchneri were found in silage but not in ensiling materials. Several other lactic acid bacteria were also identified in SCT and BGT silages, but did not appear to be related to fermentation and aerobic stability.     

Accuracy and precision of total mixed rations fed on commercial dairy farms

Despite the significant time and effort spent formulating total mixed rations (TMR), it is evident that the ration delivered by the producer and that consumed by the cow may not accurately reflect that originally formulated. The objectives of this study were to (1) determine how TMR fed agrees with or differs from TMR formulation (accuracy), (2) determine daily variability in physical and chemical characteristics of TMR delivered (precision), and (3) investigate the relationship between daily variability in ration characteristics and group-average measures of productivity [dry matter intake (DMI), milk yield, milk components, efficiency, and feed sorting] on commercial dairy farms. Twenty-two commercial freestall herds were visited for 7 consecutive days in both summer and winter months. Fresh and refusal feed samples were collected daily to assess particle size distribution, dry matter, and chemical composition. Milk test data, including yield, fat, and protein were collected from a coinciding Dairy Herd Improvement test. Multivariable mixed-effect regression models were used to analyze associations between productivity measures and daily ration variability, measured as coefficient of variation (CV) over 7 d. The average TMR [crude protein = 16.5%, net energy for lactation (NE_L) = 1.7 Mcal/kg, nonfiber carbohydrates = 41.3%, total digestible nutrients = 73.3%, neutral detergent fiber = 31.3%, acid detergent fiber = 20.5%, Ca = 0.92%, p = 0.42%, Mg = 0.35%, K = 1.45%, Na = 0.41%] delivered exceeded TMR formulation for NE_L (+0.05 Mcal/kg), nonfiber carbohydrates (+1.2%), acid detergent fiber (+0.7%), Ca (+0.08%), P (+0.02%), Mg (+0.02%), and K (+0.04%) and underfed crude protein (−0.4%), neutral detergent fiber (−0.6%), and Na (−0.1%). Dietary measures with high day-to-day CV were average feed refusal rate (CV = 74%), percent long particles (CV = 16%), percent medium particles (CV = 7.7%), percent short particles (CV = 6.1%), percent fine particles (CV = 13%), Ca (CV = 7.7%), Mg (CV = 5.2%), and Na (CV = 10%). Every 0.5-percentage-point decrease in daily NE_L (CV = 1.2 ± 0.4%) was associated with 3.2 kg/d greater milk yield, 1.0 kg/d greater DMI, and 4.3% greater efficiency of production. Every 5-percentage-point decrease in variability in percent long particles (average percent long = 19.8 ± 6.5; CV = 16.1 ± 6.9%) in the TMR was associated with 1.2 kg/d greater milk yield and a 2.6% increase in efficiency of milk production. These results demonstrate the importance of ensuring TMR consistency to maximize DMI, production, and efficiency.     

Resistance to aerobic deterioration of total mixed ration silage inoculated with and without homofermentative or heterofermentative lactic acid bacteria

Wet brewers grains were stored as a total mixed ration (TMR) in laboratory silos with lucerne hay, cracked maize, sugar beet pulp, soya bean meal and molasses at 5:1:1:1:1:1 on fresh weight basis. The TMR mixture was inoculated with or without Lactobacillus casei or Lactobacillus buchneri to obtain silages with differing fermentation and stability after exposure to air. In the first experiment, ensiling was stopped at 10, 20 and 60 days, and the stability was tested for the following 7 days. Ethanol and lactic acid were the main products in untreated TMR silage, while addition of L. casei and L. buchneri increased lactic and acetic acid, respectively. No silages deteriorated in the presence of air over 7 days, regardless of inoculation, ensiling period and the level of yeasts determined at unloading. In the second experiment, silos were opened at 14 days and then subjected to aerobic stability test for 14 days. Resistance to deterioration was sustained in the untreated control, even with a high population (>10⁴ cfu g^?1) of yeasts throughout the 14‐day test. Spoilage was found in L. casei‐treated silage at about 5 days, while increase of yeasts preceded the distinct heating (degradation). In L. buchneri‐treated silage, no yeasts were detected at unloading or after exposure to air. These results suggest that substantial stability can be expected in TMR silage with or without inoculation of lactic acid bacteria. This property is not associated with the counts of yeasts at loading and the characteristics of silage such as alcoholic and lactic acid fermentation. Copyright © 2007 Society of Chemical Industry     

Growth performance,blood metabolites,ruminal fermentation,and bacterial community in preweaning dairy calves fed corn silage-included starter and total mixed ration

The objective of this study was to evaluate the effects of the inclusion of whole-plant corn silage (WPCS) in a starter or total mixed ration (TMR) on growth, blood metabolites, ruminal fermentation, and microbial community in preweaning dairy calves. A total of 45 healthy dairy calves were blocked by date of birth and randomly assigned to 1 of 3 treatments: 100% calf starter (CONS), a mix of 85% calf starter and 15% WPCS [dry matter (DM) basis; CSCS], or 100% WPCS-based lactation TMR (CTMR). Pasteurized normal milk was fed to all the animals under the same regimen. The experiment ran from when the calves were 2 d old to weaning at 63 d. Milk and feed intakes were recorded daily. Growth performance data and blood samples were collected on wk 3, 5, 7, and 9 of the experiment. Rumen fluid was sampled at 40 and 60 d. The 3 treatments had different particle size fractions. The CSCS group had greater medium fraction (<19 mm, >8 mm) and particles retained on 8-mm sieves than the other 2 groups, whereas the CTMR group had the greatest long (>19 mm) and fine (<4 mm) fractions and physically effective neutral detergent fiber (NDF) on 8- and 4-mm sieves, but had the smallest short fraction (<8 mm, >4 mm) and particles retained on 4-mm sieves. The 24-h in vitro digestibility of DM, crude protein (CP), NDF, and acid detergent fiber (ADF) were decreased in order by the CONS, CSCS, and CTMR groups. Compared with the CONS group, the digestibility of ether extract (EE) was lower in the CSCS and CTMR groups, whereas the digestibility of starch was similar among treatments. During the experimental period, the DM, CP, and metabolizable energy intakes from milk, solid feed, and total feed were not affected by treatments. The NDF, ADF, and EE intakes and potentially digestible intakes were greater in the CTMR group than in the other 2 groups. With the exception that body barrel was greater for calves fed CSCS, growth parameters and blood metabolites were similar among treatments. Compared with the CSCS group, the CTMR group had greater rumen pH and total volatile fatty acids, propionate, and isovalerate concentrations, but a lower acetate:propionate ratio. The CTMR group had greater relative abundances of some cellulolytic bacteria (Rikenellaceae RC9 gut group, Christensenellaceae R7, Ruminococcaceae NK4A214, Ruminococcaceae UCG, Ruminococcus, and Erysipelotrichaceae UCG) in the rumen, which may be beneficial for the early acquisition of specific adult-associated microorganisms. In summary, a WPCS-based lactation TMR, but not the WPCS-included starter, had the potential to be an alternative starter in preweaning calves without having significant adverse effects. These findings provide theoretical and practical implications for the rational application of TMR in the early life of dairy calves.     

Effects of feeding ground versus pelleted total mixed ration on digestion,rumen function and milk production performance of dairy cows

This study evaluated the effects of feeding ground (G) versus pelleted (P) total mixed ration (PTMR) on digestibility and milk production performance of mid‐lactation dairy cows over a 42‐days period. Results showed that, compared to GTMR, feeding PTMR increased dry matter intake and digestibility, ruminal propionate proportions and milk protein percentage, but decreased acetate‐to‐propionate ratio, milk fat percentage and aldehydes, acids, alcohols, and aromatic hydrocarbon proportions in milk. The PTMR did not improve milk yield but accelerated live weight recovery of cows and led to acidosis risk in lactating cows due to negative effects on rumen fermentation.     

Including 8 hours of access to alfalfa in 1 or 2 grazing sessions in dairy cows fed a partial mixed ration: Effects on intake,behavior, digestion,and milk production and composition

The aim of this study was to evaluate the inclusion of alfalfa grazing during 8 h continuous or partitioned in 2 separated sessions of 4 h after each milking, on nutrient intake, digestibility, ruminal fermentation, feeding behavior, milk production, milk composition, and milk fatty acid profile, in late-lactation cows fed a partial mixed ration (PMR). Twelve dairy cows (193 ± 83 d in milk, 584 ± 71 kg of body weight) were housed in individual outdoor pens and assigned to treatments according to a 3 × 3 Latin square design replicated 4 times. The treatments were as follows: (1) control (T0), cows were fed a total mixed ration (TMR) provided ad libitum 20.0% crude protein (CP), 32.2% neutral detergent fiber (NDF); (2) fed a diet combining a PMR which had the same ingredient composition as the TMR (60% of ad libitum intake) + 1 session of 8 h of pasture (T8), continuous grazing alfalfa (Medicago sativa; 20.6% CP, 35.8% NDF) after the p.m. milking; and (3) PMR (60% of ad libitum intake) + 2 daily sessions of 4 h of access to pasture after each milking (T4+4). The experiment lasted 57 d and was divided into 3 periods of 19 d each. The first 12 d of each period was used for diet adaptation, and the last 7 d was used for data collection. No differences among treatments were observed for any of the productive variables, feeding efficiency, or purine derivatives excretion. Cows in T0 had greater intake and apparent digestibility of dry matter, organic matter, and nonfibrous carbohydrates compared with T4+4 and T8. Compared with T0, alfalfa grazing increased the concentration of C18:1 trans-11 and decreased those of C16:0 and C17:0 in milk fat. Cows in T4+4 consumed 1.1 more kg DM/d of alfalfa and N provided by alfalfa in the diet was 3 percentage points higher compared with T8 cows (266 vs. 229 g/d, respectively). In addition, T4+4 cows had a greater daily range of ruminal pH than T8 (0.73 vs. 0.93), and the highest concentrations of NH₃-N were recorded during the a.m. grazing session while in T8 cows it occurred during the night. In conclusion, including 8 h of alfalfa grazing in T8 and T4+4 treatments allowed the substitution between 35.8 and 38.7% of the total dry matter intake (DMI) of a PMR (with a similar CP concentration to alfalfa) for pasture, maintaining milk solids production and increasing the C18:1 trans-11 of milk fat compared with a TMR in mid late–lactation cows. In an herbage plus PMR diet, splitting the 1 continuous grazing session of 8 h into 2 sessions of 4 h increased the proportion of energy and N provided by alfalfa pasture and reduced PMR intake, without modifying the total nutrient intake or productive performance of cows.