Increased Milk Protein Content Research Articles

Splanchnic and Mammary Nitrogen Metabolism by Dairy Cows Fed Steam-Rolled or Steam-Flaked Corn

Objectives were to determine net release or uptake of α-amino N, ammonia N, and urea N across portal-drained viscera, liver, splanchnic, and mammary tissues of lactating Holstein cows (n = 6; 109±9 d in milk) fed alfalfa hay-based total mixed rations (TMR) containing 40% steam-rolled or steam-flaked corn grain. The TMR were offered at 12-h intervals in a crossover design. Blood samples were obtained from indwelling catheters in portal, hepatic, and mammary veins and mesenteric or costo abdominal arteries, every 2h for each cow and diet. Steam-flaked compared with steam-rolled corn greatly increased in vitro starch hydrolysis (56 vs. 34%). Daily intake of dry matter (18.4±0.4 kg/d), starch, N, and net energy for lactation by cows were not altered by processing corn; neither were daily yield of milk (29.1±0.7 kg/d), fat-corrected milk, nor fat-corrected milk per dry matter intake. Steam-flaking tended to increase percent milk protein (2.97 vs. 2.82%; P = 0.07), but not yield, and decrease percent lactose (4.83 vs. 4.94) but not yield. Portal and hepatic blood flows were not affected by diet, nor were net absorption of α-amino N and ammonia N. Steam-flaking compared with steam-rolling increased urea N cycling to portal-drained viscera (212 vs. 87 g/d) by 140%, estimated mammary uptake and extraction ratio of α-amino N. Flaking versus rolling of corn improved N utilization in dairy cows by increasing urea cycling to the gut and uptake of α-amino N by the mammary gland. Higher mammary uptake of α-amino N (78 vs. 50 g/d) by dairy cows fed steam-flaked corn tended to increase milk protein content and may explain the previously observed effects of cows fed steam-flaked versus steam-rolled corn.

Effects of the level and source of dietary protein on intake and milk yield in dairy cows

The objectives of this trial were to determine the effect of dietary protein content and the effect of the source of protein supplements on dry matter intake (DMI) and milk yield in dairy cows fed ad libitum. In addition, the interaction of protein supplement with the level of milk yield was stud- ied to test the hypothesis that the DMI response to protein supplement depends on the nutrient requirements of the cows. Two groups of six lactating cows differing in milk yield (45 kg .d -1 and 38 kg.d -1 pre-treatment) were assigned to a double 3 〈 3 Latin square design over periods of 3 weeks. The 3 treatments consisted of 3 complete diets (60% maize silage and 40% concentrate) with different protein sources and levels: low-protein supplement (LP) (5% soybean meal + 1.2% of urea in the diet), high-protein supplement containing soybean meal (HP-SB) (19% soybean meal) and high-protein supplement containing formaldehyde-treated soybean meal (HP-FTSB) (12% formalde- hyde-treated soybean meal + 1.2% of urea in the diet). HP treatments significantly increased ( P < 0.05) DMI (+1.2 kg.d -1 ), milk yield (+1.8 kg.d -1 ), 4% FCM (+2.5 kg.d -1 ) and fat content (+1.9 g .kg -1 ) com- pared to the LP treatment. These improvements were not related to the source of protein used or the level of milk yield. Compared to LP treatment, the HP-SB treatment increased milk protein content (+1.4 g.kg -1 ) (P < 0.05), whereas the HP-FTSB treatment had no significant effect. Intake and milk yield were increased by higher protein content in the diets independently of the source of protein used or the level of milk yield. dairy cow / intake / protein / milk yield

The effects of feeding different starch sources and concentrations on milk production of high yielding Holstein cows

Mansbridge (1995) reported that replacing ground wheat with a mix of ground wheat and maize grain increased milk protein concentration, which led the authors to speculate that increased inclusion of maize grain increased rumen by-pass starch. Indeed, de Visseret al(1990) reported that feeding less rapidly degradable starches has led to increased milk protein concentration.The objective of this study was to examine the effects of starch concentration and source on feed intake, milk yield and milk composition of dairy cows.

Effect of Fat and Protein Content of Milk from Individual Cows on the Specificity Rates of Antibiotic Residue Screening Tests

The effect of high concentrations of milk protein and milk fat on the specificity rates of several antibiotic residue screening tests was evaluated in this study. Milk was sampled from 60 Jersey and 30 Holstein cows at one milking and analyzed for β-lactam residues using four antibiotic residue screening tests. Cows selected were not treated with an antibiotic for at least 30 d prior to sample collection, and milk was visibly normal. Before milk collection, quarter foremilk was aseptically sampled for mastitis pathogen analysis. Milk subsamples were analyzed for fat and protein contents, and somatic cell counts (SCC). Ten Jersey and four Holstein cows were infected with one or more mastitis pathogens. Concentrations of milk fat (4.78 vs. 3.39%) and protein (3.81 vs. 3.00%) were greater for Jersey cows compared with Holstein cows. Milk SCC averaged 148,000/ml and did not differ by breed. The specificity rates were greater than 0.9 for three of the four screening tests. Across breeds, there was an increased probability of a false-positive outcome for the Penzyme test (Coulter Food Science, Milwaukee, WI)), with increased milk protein content and decreased SCC. Increased milk fat content was associated with an increased probability of false-positive outcomes for the CITE Snap test (IDEXX Laboratories, Inc., Westbrook, ME). High concentrations of milk protein and milk fat can adversely affect antibiotic residue test performance, but the degree of the effect is dependent upon the analytical method of the screening test.

The effect of crop maturity on the nutritional value of maize silage for lactating dairy cows. 3. Food intake and milk production

AbstractFifty-five multiparous Holstein-Friesian cows were used in a 20-week continuous design study to determine the effect of maize silage maturity on food intake and milk production. Forage maize (cv. Hudson) was harvested and ensiled at target dry matter (DM) contents of 230 (T23), 280 (T28), 330 (T33) and 380 (T38) g per kg fresh weight (FW). The mean values for volatile-corrected DM (VCDM), starch, neutral-detergent fibre (NDF), crude protein and predicted metabolizable energy (ME) content of the four maize silages were 226, 290, 302 and 390 g/kg FW, 114, 274, 309 and 354 g/kg VCDM, 574, 447, 431 and 448 g/kg VCDM, 96, 80, 74 and 75 g/kg VCDM and 10·3, 11·5, 11·6 and 11·2 MJ/kg DM, respectively. Grass silage containing 296 g VCDM per kg FW was produced from the primary growth of a perennial ryegrass sward. At week 3 of lactation cows were allocated to one of five forage treatments offered ad libitum. The forage treatments were either grass silage alone (TGS) or a 3 : 1 DM ratio of maize and grass silage designated as T23, T28, T33 and T38. All cows also received 8·7 kg DM per day of a dairy concentrate. Forage VCDM intake for TGS was lower (P &lt; 0·001) than for T23 to T38. Increasing maize silage DM content from 226 (T23) to 290 (T28) g/kg increased (P &lt; 0·05) forage VCDM intake from 10·9 to 13·3 kg/day but a further increase to 390 (T38) g/kg tended to reduce VCDM intake. When compared with TGS, the inclusion of maize silage increased milk yield from 28·0 kg/day to 29·4, 32·7, 33·0 and 30·8 kg/day for T23 to T38, respectively, the increases being significant for T28 to T38. However, milk yield was reduced (P &lt; 0·05) when the DM content of the maize silage increased from 302 to 390 g/kg. Increasing maize silage DM content from T23 to T33 reduced (P &lt; 0·05) milk fat content from 45·8 to 41·8 g/kg, which was also lower (P &lt; 0·05) than for TGS. The inclusion of maize silage increased fat yield with a significant difference (P &lt; 0·05) between TGS and T28. The inclusion of maize silage increased milk protein content (P &lt; 0·05) and protein yield (P &lt; 0·001) when compared with TGS. While increasing maize silage maturity did not affect (P &gt; 0·05) milk protein content, protein yield was higher (P &lt; 0·05) for the two intermediate DM contents. There were no treatment effects on body condition score. It is concluded that the changes in composition of maize silage with increasing maturity, which are associated with increased starch and reduced NDF content, resulted in large increases in food intake and yield of milk and protein as crops matured from T23 to T33. However, when crop maturity increased further to T38 there was a tendency for DM intake and yield of milk and protein to decline.

Growth Performance of Growing-Finishing Pigs Fed Diets Supplemented with Chinese Cottonseed Meal Based on Amino Acid Digestibilities

Birdsfoot trefoil (Lotus corniculatus) increases milk yield of dairy cows. An indoor feeding experiment using Friesian dairy cows in mid lactation was conducted to determine what proportions of the milk yield and composition changes were due to the condensed tannins (CT) in Lotus, and what proportions were due to factors associated with legumes (higher herbage intake and forage quality). Cows were fed either perennial ryegrass or Lotus, and were also drenched with either polyethylene glycol (PEG) to block the action of CT, or water. Milk yields (kg/cow/d) were higher on Lotus (21.24) than on Lotus+PEG (18.61), ryegrass (15.53) or ryegrass+PEG (15.49) indicating that CT contributed to 46% of the increased milk yield that resulted from feeding Lotus rather than ryegrass. CT had no effect on intake, but contributed to increased milk protein concentration, increased efficiency and decreased milk fat concentration.

Applying current technology to improve milk protein at farm level

AbstractImproving milk protein concentration at farm level can add fifty pounds per cow to milk sales annually. The benefit for processors is an increase in protein supply by ten percent and improved milk processability. The farm changes needed to improve milk protein content can also lead to a reduction in milk production costs of at least fifty pounds per cow. The objective of the Kerry Agribusiness/Teagasc “Focus on Profit” project was to adopt current technology in relation to improving milk protein at farm level to enable farmers to improve their income. Specifically to improve milk value by 0.85 p/litre by increasing milk protein content from 32 g/kg, the Kerry average for 1994, to 34 g/kg by the year end 2000. Thirty five farmers were selected to represent each category of milk supplier to Kerry Agribusiness in relation to scale of production, size of holding, soil type, farm management practices and farm location. Herds were milk recorded. Milk volume, protein and butterfat concentration, production costs, farm characteristics and management practices were monitored. Current information/technology from research on improving milk protein content and reducing costs was communicated to monitor farms by means of farm visits, farm walks, demonstrations, discussion groups, clinics, seminars, newsletters, booklet, press articles and the radio by advisors and research personnel from Kerry Agribusiness, Teagasc, Munster Cattle Breeding Society, Department of Agriculture and New Zealand. From 1994, milk protein concentration has increased by 1.1 g/kg from 31.7 to 32.8, butterfat concentration has increased by 2.4 g/kg from 35.2 to 37.6 g/kg and milk value has increased by 0.97 p/litre from 20.23 to 21.20 p/litre. The best improvement in milk protein was observed during January, February and March — 0.27 g/kg, 0.36 g/kg and 0.24 g/kg respectively. Twelve monitor farmers had protein content in their milk greater than 32.0 g/kg in 1994. This increased to 33 farmers by 1998 of which 14 had milk protein content greater than 33.0 g/kg. Thirty two (91%) of monitor farmers improved milk protein by over 0.1 g/kg, six increased milk protein by over 2.0 g/kg. Milk costs were reduced by 0.7 p/litre by monitor farmers when 1995 was compared to 1998. This reduction was 1.74 p/litre from 4.66 p/litre to 2.92 p/litre when 1995 was compared with 1997. By applying current information/technology, Kerry Agribusiness monitor farmers increased milk protein content and reduced milk production costs.

The effects of energy source and level of digestible undegradable protein in concentrates on silage intake and performance of lactating dairy cows offered a range of grass silages

AbstractThe effects of energy source and level of digestible undegraded protein (DUP) in concentrates on silage intake and performance of lactating dairy cows, offered one of a range of grass silages differing in digestibility and intake characteristics, were evaluated in a partially balanced change-over design experiment involving 48 cows. Four silages were prepared using differing management practices prior to and during ensiling. All silages were treated with an inoculant additive. For silages A, В, С and D, dry matter (DM) concentrations were 199, 320, 313 and 223 (s.e. 4.6) g/kg, pH values 3.82, 4.03, 4·03 and 5·27 (s.e. 0.056), ammonia nitrogen (N) concentrations 58, 122, 66 and 356 (s.e. 13.2) g/kg total N and in vivo DM apparent digestibilities 077, 0.75 , 0.60 and 0.60 (s.e. 0·013) respectively. When offered as the sole diet to 12 dairy cows in a partially balanced change-over design experiment, silage DM intakes were 14.7, 14.7, 12.7 and 10.5 (s.e. 0·36) kg/day respectively for silages А, В, С and D. Six concentrates containing three starch concentrations, each at two levels of DUP, were formulated to have similar concentrations of crude protein, metabolizable energy (ME) and fermentable ME. For the low and high starch concentrates and low and high levels of DUP, starch concentrations were 22·5 and 273 g/kg DM and DUP levels were 44 and 60 g/kg DM respectively. Silages were offered ad libitum supplemented with 10 kg fresh concentrate per head per day. For silages А, В, С and D, DM intakes were 10.8, 11.2, 10·7 and 9·1 (s.e. 0·26) kg/day and milk yields 29.0, 27.6, 27.1 and 25.7 (s.e. 0.69) kg/day respectively. With the exception of milk protein concentration there were no significant (P&gt; 0.05) silage type by concentrate energy source and/or level of DUP interactions on silage intake, milk output or composition. Concentrate energy source had no effect (P&gt; 0.05) on silage DM intake, the yields of milk, fat, protein or fat plus protein or milk fat concentration. However, increasing starch concentration increased milk protein concentration (P&lt; 0·001), urinary allantoin concentration (P&lt; 0·01) and diet apparent digestibility (P&lt; 0·001). Altering concentrate DUP level had no effect (P&gt; 0·05) on silage DM intake, yields of milk, protein, fat or fat plus protein, milk f at concentrations or diet apparent digestibility. Increasing the level of DUP decreased milk protein (P&lt; 0·05) concentration. It is concluded that with silages of varying digestibility, fermentation and intake characteristics, there were no concentrate energy source and/or level of DUP by silage type interactions on silage intake, milk yield or composition, or diet apparent digestibility with the exception of a silage type by concentrate level of DUP interaction on milk protein concentration. With out-of-parlour feeding of concentrates the results of the present study suggest that there is no evidence to justify the formulation of concentrates differing in energy source or level of DUP to complement individual silage types.

Response of lactating dairy cows to steam-flaked sorghum, steam-flaked corn, or steam-rolled corn and protein sources of differing degradability.

Protein sources with different degradabilities were fed to 48 lactating Holstein cows receiving 37 or 39% of dietary dry matter as steam-flaked sorghum (360 g/L), steam-flaked corn (360 g/L), or steam-rolled corn (490 g/L) in a 3 x 2 factorial arrangement of treatments. Cows were fed an alfalfa-based diet with 7% soybean meal or 5% of an animal-marine protein blend and 37 or 39% grain. Although not significant, cows fed flaked grain yielded a mean of 1.5 kg/d more milk than did those fed rolled grain. Gross feed efficiency was not affected by grain processing or protein source, but diets with the animal-marine protein blend had 9% higher estimated net energy for lactation than did diets with soybean meal. The greater gains in body weight and increased digestibility of the diets with the animal-marine protein blend verify the higher energy concentration of those diets. Yield of milk protein was increased by flaked grain or the animal-marine protein blend, and flaked grain increased percentages of lactose and solids nonfat. Increasing the ratio of rumen-degradable starch to rumen-degradable protein increased milk protein content and yield linearly and increased contents of lactose and solids nonfat. A linear response of dry matter, organic matter, crude protein, and starch digestibilities was observed as the ratio of rumen-degradable starch to rumen-degradable protein increased. These data show improved performance of dairy cows fed a high rumen-undegradable protein source with diets high in rumen-degradable starch from steam-processed grains.

An examination of the effect of concentrate energy source on rumen fermentation characteristics of dairy cattle offered grass silages of differing intake characteristics

Recent dairy cow production studies (Keady et al, 1998a, b) have indicated that energy source (starch v fibre) in the concentrate did not alter silage intake or milk yield of lactating dairy cattle offered a range of grass silages. However in both studies increasing the level of starch in the concentrate increased milk protein concentration and tended to decrease milk fat concentration. The present study was undertaken to examine the effects of concentrate energy source on rumen fermentation characteristics of dairy cattle offered three grass silages.Three silages were produced from predominantly perennial ryegrass swards after 39 day regrowth intervals. Silages A and C were ensiled from primary regrowths treated with an inoculant while silage B was ensiled from a secondary regrowth untreated. Silage A was wilted for 24 hours prior to ensiling while silages B and C were ensiled direct. Two concentrates, 0s and 100s were formulated to contain different starch concentrations but similar concentrations of crude protein, metabolisable energy, digestible undegradable protein and effective rumen degradable protein.

The effect of dietary fat and metabolizable energy supply on milk protein concentration of dairy cows

AbstractTo investigate the effect of dietary fat and metabolizable energy (ME) on milk protein concentration, an experiment was carried out using 12 multiparous early-lactation Holstein-Friesian dairy cows. Three diets were offered in a complete Latin-square change-over design, based on ad libitum access to grass silage. One of three concentrates was offered at a rate of 12 kg/day, each formulated to supply one of two levels of ME (12·1 and 13·6 MJ/kg dry matter (DM)) and one of two levels of fat (31 and a mean of 88 g acid hydrolysis ether extract per kg DM): low energy, high fat (LEHF); low energy, low fat (LELF); and high energy, high fat (HEHF). The concentration of milk protein was significantly higher from animals offered the LELF concentrate (32·5 v. a mean of 31·2 (s.e.d. 0·45) g/kg, P &lt; 0·05), because of lower milk yields (31·0 v. a mean of 33·4 (s.e.d. 0·63) kg/day, P &lt; 0·05). Animals offered the HEHF concentrate produced the highest yields of milk protein but their milk had the lowest concentrations of fat (32·5,34·4 and 31·9 g/kg for LEHF, LELF and HEHF respectively; s.e.d 1·07; P &lt; 0·05 for difference between LELF and HEHF). Silage DM intake was significantly increased by animals offered the LEHF concentrate (9·1, 8·6 and 8·7 (s.e.d. 0·19) kg/day, P &lt; 0·05 for differences between LEHF and the other two concentrates). Urinary purine derivative excretion, used as an index ofmicrobial protein supply, was highest from animals offered the LELF and HEHF concentrates, which both supplied similar amounts of fermentable ME. It is hypothesized that increased de novo synthesis offatty acids on the low fat diet reduced the availability of glucose for lactose synthesis, leading to reduced milk yields and hence increased milk protein concentrations.

The effects of concentrate energy source on silage intake and animal performance with lactating dairy cows offered a range of grass silages

AbstractA partially balanced change-over design experiment was made to examine the effects of concentrate energy source on the voluntary food intake and animal performance of 50 lactating dairy cows offered a diverse range of grass silages. The silages were also offered as the sole diet to 10 dairy cows in a partially balanced change-over design experiment. A total of five silages were prepared. Silages A, B and D and silages C and E were harvested from primary regrowths and secondary regrowths respectively of predominantly perennial ryegrass swards. Herbage was ensiled either pre-wilted or unwilted and either untreated or treated with a bacterial inoculant or formic acid based additives. For silages A, B, C, D and E, dry matter (DM) concentrations were 473, 334, 170, 170 and 256 (s.e. 4·0) g/kg, pH values 4·42, 4·01, 4·88, 4·46 and 3·91 (s.e. 0·059), ammonia-nitrogen (N) concentrations 86, 88, 289, 182 and 135 (s.e. 10·6) glkg total N and in vitro DM apparent digestibilities 0·76, 0·76, 0·75, 0·73 and 0·75 (s.e. 0·009) respectively. When offered as the sole diet DM intakes were 14·1,14·7,10·5,10·1 and 11·5 (s.e. 0·50) kg/day. Five concentrates were formulated to contain similar concentrations of crude protein, effective rumen degradable protein (ERDP), metabolizable energy (ME) and fermentable ME (FME) but using different carbohydrate sources to achieve a wide range of starch concentrations. For the low and high starch concentrates, starch concentrations were 50 and 384 g/kg DM, and acid-detergent fibre concentrations were 128 and 75 g/kg DM respectively. The silages were offeredad libitumsupplemented with 10 kg concentrate per head per day. For silages A, B, C, D and E silage DM intakes were 10·6, 10·5, 8·5, 8·6 and 9·0 (s.e. 0·37) kg/day and milk yields 23·9, 28·1, 26·2, 26·1 and 25·0 (s.e. 0·76) kg/day respectively. Concentrate energy source did not influence (P &gt; 0·05) silage DM intake, diet apparent digestibility or the yields of milk or fat plus protein. For concentrates containing 50, 131, 209, 310 and 384 g starch per kg DM, milk protein concentrations were 32·0, 32·2, 32·5, 33·0 and 33·6 (s.e. 0·13) glkg, milk fat concentrations were 44·5, 43·9, 43·8, 43·3 and 43·1 (s.e. 0·35) glkg and urinary allantoin concentrations 15·2,15·4, 17·0, 1.7·6 and 18·0 mmolll respectively. Increasing starch intake resulted in positive and negative linear relationships for milk protein (P&lt; 0·01, R2 = 0·96) and fat (P&lt; 0·01, R2 = 0·96) concentrations respectively. There were no significant concentrate energy source × silage type interactions on silage intake or yields of milk or fat plus protein (P &gt; 0·05). However there was a concentrate energy source × silage type interaction on milk fat yield (P &gt; 0·05). It is concluded that, with silages of varying fermentation and intake characteristics but similar apparent digestibility, there were no concentrate energy source × silage type interactions on food intake, milk composition or milk yield. Also concentrate energy source had no effect on silage DM intake or milk yield. However increasing starch intake linearly increased milk protein concentration, probably due to increased microbial protein synthesis and decreased milk fat concentration.

Influence of Fat Source and Sorghum Grain Treatment on Performance and Digestibilities of High Yielding Dairy Cows

Forty-eight lactating Holstein cows averaging 81 d in milk were allotted to eight blocks based on milk yield during the 14-d pretreatment period and randomly assigned to six treatment groups in a 2×3 factorial arrangement of treatments for 64 d. Factors were type of sorghum grain processing dry-rolled vs. steam-flaked; fed at 34% of dry matter (DM) in a total mixed ration (TMR) based on alfalfa] and type of supplemental fat (2.5% of DM as cottonseed oil, tallow, or prilled fatty acids). Compared with dry-rolled sorghum, steam-flaked sorghum did not affect milk yield, fat percentage, or fat yield but did increase milk protein percentage, body weight gains, and estimated net energy for lactation (22%). Fat source did not affect lactational response, but, compared with tallow, prilled fatty acids tended to decrease DM intake. Steam-flaked sorghum, compared with dry-rolled sorghum, increased digestibilities of DM, organic matter, crude protein, and starch, regardless of fat source. The TMR containing prilled fat had lower digestibilities of DM and organic matter than did TMR containing cottonseed oil or tallow; and TMR containing prilled fat had lower digestibilities of crude protein and total fatty acids than did TMR containing tallow. This study showed that steam-flaking of sorghum grain increased milk protein content, body weight gains, and estimated net energy for lactation, regardless of dietary fat source.

Response of Lactating Cows to Methionine or Methionine Plus Lysine Added to High Protein Diets Based on Alfalfa and Heated Soybeans

Lactation diets based on wilted alfalfa silage and heated whole soybeans are common in the mid-western US. We examined the milk production response of multiparous Holstein cows to the addition of ruminally protected methionine at two percentages to a basal total mixed ration. An additional total mixed ration included both methionine and lysine supplementation. Sixteen Holstein cows in early lactation were used in a replicated 4 x 4 Latin square design with 21-d periods. Milk production, milk composition, and dry matter intake were determined for the last 5 d of each period. Milk production (41.5 kg/d), dry matter intake (25.9 kg/d), and milk fat concentration (3.26%) were unaffected by the supplementation of amino acids. The addition of methionine increased milk protein concentration and yield linearly. Each gram of methionine increased milk protein yield by 4g, and milk protein concentration increased from 2.89 to 2.99% with the addition of 10.5 g/d of methionine. The proportion of casein N in total milk N was unaffected by treatment. The addition of lysine did not elicit a response. Total mixed rations based on alfalfa haylage, heated soybeans, and animal proteins were clearly limited by their methionine content but were adequate in their lysine content.

The effects of offering sucrose and fishmeal to dairy cows receiving different levels of concentrates on food intake and animal performance

Quota restricts the volume and butterfat content of milk at farm level. However there is no restriction on milk protein concentration. In a previous study in the present series, sucrose supplementation of cows in late lactation offered grass silage based diets increased milk protein concentration, while supplementation with sucrose and fishmeal increased protein concentration and the yields of milk, protein and fat plus protein equivalent to, or greater than, that obtained from the parent herbage. The present study was undertaken to evaluate the effects of partially replacing a concentrate supplement with sucrose and/or fishmeal, over a range of concentrate feed levels, on forage intake, milk production and composition.Herbage was harvested from the primary growth of a predominantly perennial ryegrass sward, unwilted, precision chopped and treated with a formic acid based additive (Add-Safe, Trouw Nutrition) at 2.85 l/t. A concentrate was formulated consisting of unmolassed sugar beet pulp, barley, soyabean meal and minerals and vitamins. Four complete diets were prepared consisting of the silage and either concentrate (20 g/kg fresh silage) (SC), concentrate and sucrose (each at 10 g/kg fresh silage) (SCS) concentrate and fishmeal (each at 10 g/kg fresh silage) (SCF) or sucrose and fishmeal (each at 10 g/kg fresh silage) (SSF).

Effects of inoculant treatment on ryegrass silage fermentation, digestibility, rumen fementation, intake and performance of lactating dairy cattle

AbstractA randomized block experiment involving thirty‐six lactating dairy cattle was carried out to evaluate a bacterial inoculant (Grazyme Grobac, Agritech), containing bacteria, enzymes and a rumen enhancer, as a silage additive. Herbage from the primary regrowth of predominantly perennial ryegrass swards was ensiled unwilted and precision‐chopped after a 51‐d growth interval on 4 and 5 August. Alternate loads of herbage were ensiled either untreated (C) or treated with formic acid at a rate of 2.65 1 (t herbage)−1 (F) or the inoculant at a rate of 0.64 kg (t grass)−1 (I). The treatments were harvested using the same harvester in the rotation of I, F and C treatments. Mean dry‐matter (DM), water‐soluble carbohydrate and nitrate nitrogen (N) concentrations and buffering capacity of the C herbages at ensiling were 198 g kg−1, 18 2 g kg−1, 290 mg (1 juice)−1 and 379 mequiv. (kg DM)−1 respectively. For silages C, F and I pH values were 3.7, 3.8 and 3.8 and ammonia N concentrations 61, 43 and 58 g (kg total N)−1 respectively. Inoculant treatment did not alter aerobic stability of the silages, whereas formic acid treatment increased it. The silages were offered ad libitum and supplemented with 5 kg of concentrates per head daily. For treatments C, F and I silage DM intakes were 10.8, 11.2 and 10.8 (s.e. 0–33) kg d−1, milk yields 21.3, 20.9 and 20.7 (s.e. 0.52) kg d−1, fat concentrations 38.3, 40.3 and 37.2 (s.e. 0.83) g kg−1 and protein concentrations 30.8, 32.6 and 32.6 (s.e. 0.49) g kg−1 respectively. Inoculant treatment did not alter (P0.05) the digestibility coefficients of the total diets, whereas formic acid treatment decreased DM (P0.05), organic matter (P0.05), neutral detergent fibre (P0.01) and hemicellulose (P0.01) digestibilities. Formic acid treatment altered rumen fermentation patterns, whereas inoculant treatment had no effect. It is concluded that, relative to a well‐preserved untreated silage, additive treatment did not alter DM intake, milk yield or fat plus protein yield. However, both additive treatments increased milk protein concentrations and formic acid treatment increased milk fat concentration relative to the well‐preserved, untreated silage.

Dietary influence on protein level in milk and milk yield in dairy cows

Diet can influence the yield of milk protein more than it can influence milk protein content. Providing sufficient dietary crude protein in forms that will maximize amounts of amino acids required for milk protein synthesis to the gastrointestinal tract, in forms that can be digested and absorbed, will provide for optimal milk protein yield and content. Maximizing ruminal microbial protein synthesis is an important part of this strategy. The rest of the strategy involves providing sufficient amounts of the remaining required amino acids as ruminally protected proteins, or amino acids in forms that can be digested in the gastrointestinal tract. A diet deficient in protein will reduce milk protein content 1 to 2 g kg −1 and may substantially reduce yields of milk and milk protein. A diet containing high amounts of readily fermentable carbohydrates may increase milk protein content 1 to 2 g kg −1, and may increase yields of milk and protein, but may also result in digestive and metabolic upsets. Diets containing supplemental fat will increase yield of milk protein, but not as extensively as the increase in yield of milk, because milk protein content is usually reduced 1 to 2 g kg −1. The increased efficiency of milk fat and lactose synthesis is likely to be the reason for this depression in milk protein content. A means of overcoming this problem is a continuing research challenge.

The influence of dietary energy source and dietary protein level on milk protein concentration from dairy cows

AbstractTo investigate the effects of energy source and protein level of diets on milk protein content, 12 multiparous Holstein-Friesian cows were used in a 4 × 4 Latin square change-over experiment with 4-week periods. Four diets were offered, withad libitumsilage as proportionately 0·40 of the diet, and the remaining 0·60 as one of four concentrates, two based on barley and two on molassed sugar-beet pulp. Two protein levels were achieved by altering the amounts of digestible undegraded protein in the concentrates, with all diets formulated to supply equal quantities of rumen degradable protein. There was no effect of diet on dry-matter intakes. Both starch and high dietary protein levels significantly increased milk protein concentration (P&lt; 0·05), but had no effects on milk fat and lactose concentrations. Mean milk yields were significantly higher (P&lt; 0·05) with increased dietary protein. Dietary protein significantly affected the yields of milk protein (P&lt; 0·01) and lactose (P&lt; 0·05) but not that of fat. Urinary allantoin excretion was significantly greater with both high protein (P&lt; 0·05) and starch-based diets (P&lt; 0·05). No significant interaction effects were found. It is concluded that dietary effects were due largely to differences in supply of rumen degradable protein; increases in milk protein concentration were therefore brought about by increasing the protein supply to the animal.

Responses in Milk Constituents to Intravascular Administration of Two Mixtures of Amino Acids to Dairy Cows

Four Holstein-Friesian cows were used to investigate the effects of intravascular infusions of AA mixtures on milk constituents. Cows were in wk 11 to 28 of lactation and were fed a basal concentrate (142g of CP/kg of DM) and grass silage (149g of CP/kg of DM) in a. 60:40 ratio (percentage of DM). Cows were fed hourly, and feed intake was fixed at 95% of ad libitum intake for each experimental period. Each cow received a 4-d jugular saline infusion, followed by a 5-d jugular infusion of a mixture of AA. Two mixtures of AA were used in a crossover design. The first mixture contained both the essential AA and non-essential AA found in milk protein (total AA); this mixture was infused at 400g of AA/d. The other mixture represented the essential AA fraction only and was infused at 208 g/d. Infusion of total AA increased milk protein concentration from 32.4 to 35.0 g/kg, and essential AA increased milk protein concentration from 32.5 to 36.9 g/kg; milk protein yield increased by 87 g/d (total AA) and 143 g/d (essential AA). Intravascular administration of AA specifically stimulated milk protein concentration, and the efficiency with which the AA were used was higher than had been previously reported when AA supply was increased either by dietary supplementation or by abomasal infusion.

Effects of physical treatment of barley and rapeseed meal in dairy cows given grass silage-based diets

Twenty-four Ayrshire cows were used to study the effects of physical treatment of barley, rapeseed meal (RSM) supplementation and heat-moisture treatment of RSM on silage intake and milk production. Experimental design was a cyclic change-over with six dietary treatments. The treatments in a 2 x 3 factorial arrangement consisted of either untreated (UB) or heat-moisture treated barley (TB), given without protein supplementation (control) or with untreated or heat-moisture treated RSM. Grass silage was given ad libitum and the concentrates at a rate of 10 kg/d. For the RSM diets, 2 kg/d of the basal concentrate was replaced with either untreated or treated RSM. Treatment of barley decreased silage intake, the effect being greater when the supplement did not contain RSM. There was no effect on milk yield, but due to the lower milk fat content, energy corrected milk yield was lower in cows given TB than in those given UB. Feeding the TB diets was also associated with lower milk urea content, and with increased milk protein content but not protein yield. Faster initial rate of gas production in vitro suggested that the treatment of barley increased the rate of fermentation. Compared with the control diets, RSM supplementation significantly increased silage intake, milk yield, milk protein content and yields of all milk constituents. Heat-moisture treatment of RSM did not produce any further production response.