Diet digestibility and growth of holstein calves fed acidified milk replacers containing soy protein concentrate

Three experiments were conducted to determine the effects of acidification of milk replacers containing soy protein concentrate on diet digestibility and growth of Holstein bull calves. In Experiment 1, six calves (6 wk old) were fed at 10% of BW/d either acidified milk replacer containing soy protein concentrate or untreated milk replacer containing soy protein concentrate. Replacers were reconstituted to 12.5% DM for 10-d adjustment and 4-d collection periods to determine digestibility and N balance. Digestibilities of DM, ether extract, and N were similar between treatments. Nitrogen retention and N retention as a percentage of that absorbed were higher for calves fed the acidified diet. In Experiment 2, 20 calves (1 wk old) were fed diets identical to those diets fed in Experiment 1 at 20% of BW/d for 4 wk. Calves were allowed to adjust to the diet for 5 d. Growth parameters were measured and amount of feed offered was adjusted weekly. Calves fed the untreated diet had higher daily weight gains, girth gains, height gains, and better feed utilization. In Experiment 3, 21 calves were fed either the aforementioned diets or a replacer based on milk proteins at 10% of BW/d (12.5% DM) for 4 wk. Growth parameters were measured and DM intakes were adjusted weekly. Growth and feed conversion were similar across diets. Replacers containing soy protein concentrate or large amounts of whey may need to be supplemented with additional methionine to maximize rate of gain.     

The nutritive value of cooked potato in milk replacers for young calves

The digestibility of nutrients in milk replacers were determined with Ayrshire bull calves from 7 to 28 days of age. The mean apparent digestibilities of dry matter (DM), gross energy (g.e.) and nitrogen declined from 0.84 to 0.79; 0.85 to 0.78 and 0.79 to 0.76 when cooked potato flour replaced an equivalent weight of spray-dried whey in liquid diets. Potato starch has a mean apparent digestibility of 0.65. Nitrogen retention was unaffected by diet, but the potato diet had a lower metabolisable energy value than the control diet (15.6 and 17.5 MJ per kg DM respectively). Glucose levels in the jugular blood were lower for calves fed the potato based milk replacer. The apparent digestibilities of dry matter, gross energy and nitrogen showed marked improvements with age, particularly on the potato based diet, with starch digestibility improving from 0.50 to 0.74 between 10 and 24 days. While blood glucose concentration increases with age, the relative differences between treatments remained.     

Tolerance of the preruminant calf for selenium in milk replacer

Calves were fed skim milk powder-based milk replacer containing either .2, 1, 3, 5, or 10 ppm selenium (added as sodium selenate) in the dry matter from 3 to 45 d of age to estimate the lowest amount of dietary selenium that would reduce calf performance and feed utilization. Only at the highest selenium (10 ppm) did calves show reduced average daily gain and feed efficiency and lower blood packed cell volume. Apparent digestibility of dry matter, nitrogen, and lipid, and plasma creatine phosphokinase activity were not affected by any of the selenium intakes. In general, selenium in blood, bile, duodenal mucosa, liver, kidney, and muscle reflected selenium intakes with liver and kidney reaching the highest selenium concentrations. Postmortem examinations of calves revealed no gross abnormalities for any of the selenium treatments. The preruminant calf is very tolerant of high inorganic selenium concentrations in skim milk powder-based milk replacer.     

Replacement of skimmed milk with hydrolyzed fish protein and Nixtamal in milk substitutes for dairy calves

Two experiments were conducted with 3- to 5-d-old Holstein male calves. In Experiment 1, 15 calves were assigned to three dietary treatments. The control diet was based on sodium caseinate, lard, and cerelose. In the other diets, either 50% or all carbohydrates were replaced by lime-treated corn flour (Nixtamal). In Experiment 2, 35 calves were assigned to dietary treatments in which 0, 50, or 67% low heat skimmed milk protein was replaced by hydrolyzed fish protein; for the replacement diets, Nixtamal was incorporated at 25 or 35% of the dry matter. Control diet protein was entirely from skimmed milk. Milk substitutes provided the only feed during the 8-wk experiment. In Experiment 1, body weight gain and feed efficiency declined when Nixtamal completely replaced skimmed milk but remained unchanged at 50% substitution. Substitution of Nixtamal for skimmed milk powder decreased nitrogen and carbohydrate digestibility; but digestibility improved with age. In Experiment 2, replacing up to 67% of skimmed milk protein with partially hydrolyzed fish protein concentrate had no effect on body weight gain but decreased feed efficiency linearly at 8 wk and reduced dry matter, nitrogen, and fat digestibility. Nixtamal can replace up to 50% of skimmed milk carbohydrates without detrimental effect on growth rate, feed efficiency, and diarrhea, but digestibility might be reduced. Concurrent replacement of up to 67% of skimmed milk protein with partially hydrolysed fish protein concentrate would be feasible for newborn calves gaining 450 g/d, despite lower nitrogen digestibility.     

Effects of feeding corn or barley on composition of milk and diet digestibility

Complete mixed, cubed diets containing corn or barley as the cereal component were fed to eight cows, four first lactation and four second or later lactation. Diets were fed for ad libitum intake in two periods of 21 d each. Percentages of milk fat, protein, lactose, and solids were not affected by corn or barley. Percentages of casein, whey, and nonprotein nitrogen were not different nor was proportion of total nitrogen represented as casein, whey, or nonprotein nitrogen for corn or barley diets. Production status, first lactation versus older cows, did not affect milk composition of casein, whey, and nonprotein nitrogen. Apparent digestibility of dry matter and energy was not different, but fiber digestibility was significantly lower for the barley diet. Intake of dry matter and digestible energy and yield of milk and milk constituents were not different. When diets were fed to rumen fistulated heifers, molar percentages of volatile fatty acids, total volatile fatty acid concentration, and pH of rumen fluid were not different for corn or barley diets.     

Dietary fibers and supplementary iron in a milk replacer for veal calves

Thirty 1-wk-old male Holstein calves were allotted randomly to six groups into a 3 X 2 factorial design. The control diet was skim milk, whey, tallow, vitamins, and minerals. Either Alpha-Floc or pectin was added at 5% dry matter. Supplementary iron was added at 30 and 50 ppm (dry basis). The six diets were fed for 14 wk. Calves without supplementary iron were mildly anemic at 6 wk and severely at 14 wk (7 and 5 g/dl hemoglobin). At 14 wk, both fibers had decreased blood hemoglobin in calves given supplementary iron. Feed refusal began at 8 wk with the appearance of anemia for calves unsupplemented with iron, but both Alpha-Floc and pectin decreased feed refusal. Supplementary iron practically eliminated feed refusal. Supplementary iron improved average daily gain and feed conversion, but dietary fibers had no effect. Adding Alpha-Floc and pectin to the diets reduced frequency of diarrheic feces. Mean carcass weight of calves fed supplementary iron was 11.6% higher than that of unsupplemented calves. Supplementary iron decreased liver lipids and increased glutamic oxaloacetic transaminase activity in blood plasma.     

Increased super-conditioning temperature of corn grain affects performance,skeletal growth,and blood metabolites in Holstein dairy calves

We aimed to evaluate the effects of feeding super-conditioned corn at different temperatures on intake, growth performance, total-tract starch digestibility, rumen fermentation, blood metabolites, and feeding behavior of dairy calves. Thirty-six Holstein female dairy calves (40 ± 1.72 kg of body weight, ± SD) were randomly assigned to 1 of the following 3 treatments: (1) ground corn (control; CON; n = 12), (2) corn super-conditioned at 75°C (T-75; n = 12), and (3) corn super-conditioned at 95°C (T-95; n = 12). Three mash starter feeds with an identical nutritional composition were blended with 5% chopped alfalfa hay and fed to individually-housed calves from d 3 to 77 of their birth. All calves were fed 4 L/d of pasteurized whole milk twice daily since d 3 to 56, followed by 2 L/d of morning feeding from d 57 to 63 of age. Calves were weaned on d 63 and remained in the study until d 77. The T-75 and T-95 diets increased total-tract starch digestibility compared with the CON diet. Dry matter intake and weaning or final BW were not affected by treatments; however, average daily gain and feed efficiency increased in calves fed T-95 in the overall period. The T-95 diet increased withers height and tended to increase hip height compared with other diets, but feeding behavior did not change throughout the experimental period. Ruminal pH decreased in calves fed the T-95 diet compared with T-75 and CON diets. The molar proportion of ruminal propionate increased, whereas the acetate-to-propionate ratio tended to decrease in calves fed the T-95 compared with CON diet. Calves fed the T-95 diet had the highest blood glucose concentration, whereas a trend for increased insulin concentration was observed in calves fed T-95 compared with other diets. In conclusion, super-conditioning temperature of corn (T-95 vs. T-75 and CON) improved the average daily gain, feed efficiency, and skeletal growth, but did not influence dry matter intake during the first 77 d of age. Finally, the total-tract starch digestibility increased, whereas ruminal pH dropped during the postweaning period as super-conditioning temperature elevated.     

Performance of young calves fed soybean protein replacers

In two 12-wk trials we evaluated soybean protein in calf milk replacers. In trial 1, twelve 5-day-old Holstein calves were allotted randomly to three milk replacers. The diets contained 26% crude protein. In trial 2, 18 calves were used and the diet contained 30% crude protein. In trial 1 period 1 (10 to 15 days), mean coefficients of apparent digestibility (%) for milk protein, soy protein concentrate, and full fat soy flour replacers were dry matter 92.0, 70.0, 71.0; protein 90.1, 56.6, 61.3; fat 88.9, 55.0, 53.2;; and ash 85.8, 62.5, 61.2. Average daily nitrogen retentions were 10.8, -1.24, and -.7 g. Results in period 2 (30 to 35 days) for digestibilities and nitrogen retention showed considerable improvement over those in period 1. In trial 2 period 1, mean coefficients of apparent digestibility (%) for milk protein, soy protein concentrate, and defatted soy flour replacers were dry matter 87.5, 66.6, 47.9; protein 80.5, 57.2, 28.5; fat 81.5, 55.9, 33.5; and ash 83.8, 58.9, 48.4. Average daily nitrogen retentions were 10.8, 2.9, and -3.6 g. Results in period 2 for digestibilities and nitrogen retention also showed considerable improvement. Calves are able to use soy based replacers more effectively with age.     

Effects of raw pea flour on nutrient digestibility and immune responses in the preruminant calf.

Two milk substitute diets for which the protein was provided either exclusively by skim milk powder (control) or partially (34%) by dehulled raw pea flour were given for 2 and 4 wk, respectively, to five preruminant calves, each fitted with a reentrant ileocecal cannula. Ileal apparent digestibility was lower with the pea diet during wk 1 than with the control diet. Four of the cannulated calves exhibited significant intolerance to the pea diet, resulting in lower digestibility during wk 4. In contrast, fecal digestibility of the pea diet, measured in four additional calves without reentrant cannulas, did not significantly decrease between wk 1 and 4. The AA composition of ileal digesta from the first group of calves did not vary greatly, suggesting that the differences observed in their apparent digestibility of proteins were due mainly to changes in the loss of endogenous proteins. However, pea legumin survived digestion in the small intestine in amounts generally equivalent to 1 to 3% of intake. Most of that undigested fraction was smaller than the native legumin: 40 to 200 kDa instead of 360 kDa. Also, a 45-kDa fragment was detected in the urine. Increased intestinal permeability could have favored the development of the high systemic anti-pea antibody titers that were observed in all of the calves.     

Pancreatic enzyme deficiency depends on dietary protein origin in milk-fed calves

In young mammals, milk proteins and their substitutes are used in milk formula. Protein substitution modifies diet digestibility and pancreatic secretions. The aim of this study was to test if milk protein substitution could generate pancreatic deficiency in milk-fed calves. The effect of pancreatic juice on the digestibility of proteins was studied. Measurement of apparent fecal nutrient digestibility was used to estimate digestion. Ten calves (60 to 130 d old) were chronically fitted with pancreatic accessory duct cannulas and 2 duodenal cannulas to provide precise measurement, sampling, and reintroduction of pancreatic juice as well as additional infusions. Animals were fed milk formula based on skim milk powder or soybean concentrate. Level of deficiency depended on dietary protein origin. Twice as much protein or trypsin was required with a soybean concentrate diet than with a skim milk powder diet to obtain maximal nutrient digestibility. Pancreatic protein concentration in the juice can be used to differentiate between normal and deficient animals. Among these proteins, trypsin measurement is a good pancreatic deficiency marker. These results confirmed the major role of exocrine pancreatic secretions in producing optimal digestion in young calves. Furthermore, practical applications of these results can be applied for the young in other animal species and in humans.     

Effect of Adding Dried Whey to Starter Diet of Early and Late Weaned Calves

Forty-four Holstein calves, 20 males and 24 females, were randomly assigned to one of four treatments in a 2 × 2 factorial designed experiment. Treatments consisted of early (35 d) versus late (70 d) weaning and the feeding of a pelleted starter diet containing either 0 or 24.5% dried sweet whey. Calves were housed in individual, elevated, shaded pens. Whole milk was fed at 10% of body weight adjusted weekly. The assigned starter diet and water were provided free choice beginning on the 8th d of the trial. Intakes of milk and starter diet were recorded daily. Body weight, heart girth, and wither height measurements were recorded weekly during the 14-wk trial. Calves fed the starter diet containing whey consumed less dry matter (119.2 vs. 150.7 kg) and had a lower rate of gain (.63 vs. .72 kg/d) than those fed the control starter ration. Late weaned calves consumed less starter (115.8 vs. 145.0 kg) and gained more rapidly (.74 vs. .61 kg/d) than early weaned calves. Bull calves were more efficient converters of dietary dry matter into body weight gain than heifer calves, and late weaned calves were more efficient than early weaned calves. Inclusion of whey in the starter ration did not influence feed conversion. It was concluded that the addition of whey at 24% of a pelleted starter diet depressed intake and rate of gain of calves.     

Effect of environmental temperature and dietary fat on growth and physiological responses of newborn calves

Effects of cold environmental temperature and supplemental dietary fat (energy) on growth rate and physiological responses of young dairy calves fed a milk replacer diet were studied. Thirty-six Holstein bull calves were randomly assigned to one of six treatments allotted in a 2(-4 degrees C or 10 degrees C) X 3(10, 17.5, or 25% dietary fat) factorial arrangement of treatments Calves began the experiment at an average of 6 d of age and received .6 kg dry milk replacer in 4 L of water daily for 3 wk. Average daily gains (kg/d) over the 3-wk trial for calves fed 10, 17.5, and 25% fat diets were-.04, .02, and .09 at -4 degrees C and .15, .22, and .20 at 10 degrees C. Gains were significantly lower for calves housed at -4 degrees C. Rectal temperatures were lower for calves at -4 degrees C than at 10 degrees C and for calves fed 10% versus 25% fat diet. Respiratory rates and water intakes were lower for calves housed at -4 degrees C but were not affected by diet. Concentrations of plasma glucose and prolactin were lower for calves housed at -4 degrees C while concentrations of plasma free fatty acids and growth hormone were not affected by temperature. Plasma free fatty acids were increased by dietary fat, and plasma growth hormone was reduced as dietary fat increased. Calves housed at -4 degrees C had higher maintenance energy requirements (.133 Mcal metabolizable energy/kg.75) than calves housed at 10 degrees C (.101 Mcal metabolizable energy/kg.75).(ABSTRACT TRUNCATED AT 250 WORDS)     

An oxalate-sodium hydroxide buffer to study the role of milk replacer coagulation in preruminant calves

An oxalate-NaOH buffer, which prevents coagulation in the abomasum of young calves, was added to a nonclotting milk replacer based on high heat skim milk powder, to investigate effects of this buffer on digestibility and metabolism of dietary components. Twelve Holstein male calves were allotted at random in two groups of six animals each and fed the experimental milk replacers from 3 to 17 d of age. Digestibility of dry matter, protein, and fat was similar for both control and buffered milk replacers. Concentrations of plasma glucose, triglycerides, alpha-amino nitrogen, and urea were the same in animals receiving buffer treated milk replacer and control diets. The data suggests that this oxalate-NaOH buffer would be suitable to prevent milk clotting in studies dealing with the importance of coagulation in digestion and metabolism in preruminant calves.     

Liquid egg as an alternative protein source in calf milk replacers

The use of alternative proteins in milk replacer has been evaluated for their ability to decrease the cost of milk replacers without negatively impacting performance of the calf. Three studies were conducted to evaluate the performance of calves fed milk replacer utilizing liquid egg as an alternative protein and to determine the optimal concentration of liquid egg to include in milk replacers. Calves in trials 1 and 2 were assigned to a control diet of all milk protein replacer (MILK) or a diet formulated to contain 5% of the diet (13.5% of the protein) from liquid egg (5% EGG). Calves in trial 3 were assigned to one of four diets: the control (MILK) and 5% EGG diets fed in trials 1 and 2, or diets formulated to contain either 10 or 15% of the diet (27 or 40.5% of the protein) from liquid egg (10% EGG, 15% EGG). For all experiments, milk replacers were formulated to contain 20% protein, 20% fat and were fed at 454 g/d reconstituted to 12% DM. Production of the diets containing egg protein utilized breaker eggs that were pasteurized during manufacturing. Holstein bull calves (n = 44 for experiment 1, n = 38 for experiment 2, and n = 120 for experiment 3), were purchased from an area sale barn. Calves were housed in individual hutches with water available free choice starting on d 0. A commercially available calf starter was offered free choice beginning on d 7 for experiments 1 and 2 and on d 1 for experiment 3. Feed intake, scour scores, and antibiotic treatments were recorded daily. For experiment 1, calves fed 5% EGG had greater weight gains than calves fed MILK. No differences in average daily feed intake were observed. For experiment 2, weight gains tended to be lower with 5% EGG, whereas feed intakes and gain to feed ratios were similar between calves fed MILK or 5% EGG. For experiment 3, as the amount of egg in the diet increased, weight gain decreased in a linear fashion during the milk replacer feeding period, but the decrease in gain was significant only with the 15% EGG diet. These results indicate that egg is an effective alternative protein source to milk protein in calf milk replacers when fed at levels up to 10% of the diet in a conventional feeding program of 0.45 kg per head per day.     

Effects of protein content and rumen-undegradable to rumen-degradable protein ratio in finely ground calf starters on growth performance,ruminal and blood parameters,and urinary purine derivatives

This study investigated the effects of feeding finely ground starter diets containing either 18 or 22% crude protein (CP) content [dry matter (DM) basis] and high or low ratios of rumen-undegradable protein to rumen-degradable protein (RUP:RDP) on growth performance, nutrient digestibility, ruminal fermentation, blood metabolites, and urinary purine derivatives in dairy calves. A total of 48 three-day-old female Holstein dairy calves with 40.2 ± 2.5 kg of initial body weight (BW) were randomly assigned in a complete randomized block design to a 2 × 2 factorial arrangement of treatments (12 calves/treatment). Treatments were as follows: (1) finely ground starter diet (mean particle size = 0.69 mm) with 18% CP and low RUP:RDP ratio [low ratio (LR) = 26:74; 18CP-LR]; (2) finely ground starter diet with 18% CP and high RUP:RDP ratio [high ratio (HR) = 35:65; 18CP-HR]; (3) finely ground starter diet with 22% CP and low RUP:RDP ratio (22CP-LR); (4) finely ground starter diet with 22% CP and high RUP:RDP ratio (22CP-HR) on DM bases. Blocking was based on the day of treatment assignment, and treatments were randomly assigned within each block. Calves received 4 L of milk daily from d 3 to 10, 7 L/d from d 11 to 40, 4 L/d from d 41 to 49, and 2.5 L/d from d 50 to 53, and then all calves were weaned but remained in the experiment until d 83 of age. The results showed that overall average daily gain (ADG), weaning BW, and feed efficiency (FE) were greater in 22% CP treatments than in 18% CP. Increasing the starter CP content from 18 to 22% of DM did not influence overall starter feed intake, milk intake, total dry matter intake (DMI), postweaning ADG, and FE of calves. No effect of RUP:RDP ratio was observed for starter feed intake, milk intake, total DMI, preweaning ADG, FE, and grams of CP per megacalorie of metabolizable energy. The RUP intake and postweaning ADG were greater for calves fed the HR diets than for those fed the LR diets. The digestibility of neutral detergent fiber was greater, and the digestibility of OM tended to be greater, and the ruminal concentrations of total short-chain fatty acids (SCFA), acetate proportion, and acetate-to-propionate ratio were greater in 22% CP than in 18% CP. A 2-way interaction between starter protein content and time was observed for total ruminal SCFA, acetate proportion, and acetate-to-propionate ratio, indicating that starter CP concentration had more effect on ruminal parameters. Preweaning urinary purine derivatives, preweaning microbial protein synthesis, and postweaning urinary nitrogen were greater for calves fed the 22CP diets than for those fed the 18CP diets but were not affected by the different RUP:RDP ratios. The concentrations of blood glucose and insulin were greater in 22% CP than in 18% CP diets. The blood insulin concentration was greater when calves received the HR diets compared with the LR diets. Therefore, we conclude that greater starter protein content can have beneficial effects on growth performance, probably through increased microbial protein synthesized and preweaning blood insulin concentration; however, a greater RUP:RDP ratio showed marginal effects on growth performance during the postweaning period.     

Soy protein concentrate and heated soy flours as protein sources in milk replacer for preruminant calves

Thirty-two male calves (8/treatment) in Trial 1 and 41 male and female calves (10 or 11/treatment) in Trial 2 were fed milk replacers containing 100% of the total protein from milk sources or 25% from milk and 75% from a soy product: soy protein concentrate; commercial heated (fully cooked) soy flour; or experimental soy flour for 6 wk. The experimental flour received moist heat sufficient to reduce trypsin inhibitor to 1 unit/mg. Calf performance improved with age on all diets. Growth, protein and dry matter digestibility, nitrogen retention, and morphology of the intestinal mucosa of calves on the all milk-protein diet were superior to those of calves on diets containing a soy product. All soy-fed groups had a humoral but no cell-mediated immune reaction to soy proteins. Soy protein concentrate and the experimental heated soy flour were superior to the commercial heated soy flour as protein sources for milk replacer.     

Addition of sodium bicarbonate to calf starter rations varying in protein percent

The influence of added sodium bicarbonate on calf performance and on a possible sparing effect on dietary protein was studied with 48 Holstein calves. Calves were assigned randomly to one of four starter diets containing 10% chopped hay in a 2 X 2 factorial designed experiment: 1) 12% crude protein, 0% sodium bicarbonate; 2) 12% crude protein, 3% sodium bicarbonate; 3) 17% crude protein, 0% sodium bicarbonate; and 4) 17% crude protein, 3% sodium bicarbonate. All calves were fed fermented colostrum for 5 wk and offered their respective starter diets from birth until 10 wk of age. Average daily gains and daily dry matter intakes for wk 0 to 5 were .24, .25; .28, .24; .26, .19; and .27, .24 kg for diets 1 to 4 and for wk 6 to 10 were .52, 1.64; .50, 1.73; .67, 1.78; and .63, 1.87 kg. Addition of sodium bicarbonate (diets 2 and 4) stimulated greater growth (0 to 5 wk) and higher feed intake for the 10-wk trial. Digestibilities of all nutrient measures at wk 9 were lower with added sodium bicarbonate and may be related to higher feed intake. Added sodium bicarbonate did not influence nitrogen digestibility. However, the higher protein diet with sodium bicarbonate improved nitrogen utilization. Rumen samples collected at 9 wk tended to have a higher pH and ratio of acetate: propionate with added sodium bicarbonate. Calves fed the high protein diets gained more weight and consumed more feed than calves fed the low protein diets.     

Diet supplementation with canola meal improves milk production,reduces enteric methane emissions,and shifts nitrogen excretion from urine to feces in dairy cows

The objective of this study was to examine the effect of isonitrogenous substitution of solvent-extracted soybean meal (SBM) with solvent-extracted canola meal (CM) on enteric CH₄ production, ruminal fermentation characteristics (including protozoa), digestion (in situ and apparent total-tract digestibility), N excretion, and milk production of dairy cows. For this purpose, 16 lactating Holstein cows, of which 12 were ruminally cannulated, were used in a replicated 4 × 4 Latin square (35-d periods; 14-d adaptation). The cows averaged (mean ± SD) 116 ± 23 d in milk, 692 ± 60 kg of body weight, and 47.5 ± 4.9 kg/d of milk production. The experimental treatments were control diet (no CM; 0%CM) and diets supplemented [dry matter (DM) basis] with 7.9% CM (8%CM), 15.8% CM (16%CM), or 23.7% CM (24%CM) on a DM basis. The forage:concentrate ratio was 52:48 (DM basis) and was similar among the experimental diets. Canola meal was included in the diet at the expense of SBM and soybean hulls, whereas the percentages of the other diet ingredients were the same. Intake of DM increased linearly, whereas apparent total-tract digestibility of DM, crude protein, neutral detergent fiber, and gross energy (GE) declined linearly as CM inclusion in the diet increased. Total volatile fatty acids concentration and butyrate molar proportion decreased linearly, whereas molar proportion of propionate increased linearly, and that of acetate was unaffected by CM inclusion in the diet. Ruminal ammonia concentration was not affected by inclusion of CM in the diet. Energy-corrected milk (ECM) yield increased linearly (up to 2.2 kg/d) with increasing CM percentage in the diet, whereas milk production efficiency averaged 1.63 kg of ECM/kg of DM intake and was unaffected by CM inclusion in the diet. Daily CH₄ production decreased linearly with increasing CM percentage in the diet (489, 475, 463, and 461 g/d for 0%CM, 8%CM, 16%CM and 24%CM diets, respectively). As a consequence, CH₄ emission intensity (g of CH₄/kg of ECM) also declined linearly by up to 10% as the amount of CM increased in the diet. Methane production also decreased linearly when expressed relative to GE intake (5.7, 5.2, 5.1, and 4.9% for 0%CM, 8%CM, 16%CM and 24%CM diet, respectively). Quantity of manure N excretion was not affected by replacing SBM with CM; however, N excretion shifted from urine to feces as dietary percentage of CM increased, suggesting reduced potential for N volatilization. Results from this study show that replacing SBM with CM as a protein source in dairy cow diets reduced enteric CH₄ emissions (g/d, % of GE intake, and adjusted for milk production) and increased milk production. The study indicates that CM can successfully, partially or fully, replace SBM in lactating dairy cow diets, with positive effects on animal productivity and the environment (i.e., less enteric CH₄ emission and urinary N excreted). We conclude that compared with SBM, inclusion of CM meal in dairy cow diets can play a key role in reducing the environmental footprint of milk production.     

Soybean oil supplementation and starter protein content: Effects on growth performance,digestibility, ruminal fermentation,and urinary purine derivatives of Holstein dairy calves

This study investigated the effects of feeding dairy calves starter diets containing 19% or 22% crude protein (CP) content on a dry matter basis and either supplemented or not with soybean oil (SBO, 0 vs. 3%, dry matter basis) on growth performance, digestibility, urinary nitrogen, and purine derivatives (PD) excretion. A total of 48 female Holstein dairy calves (mean 39.8 kg of body weight) were randomly distributed to experimental diets in a 2 × 2 factorial arrangement of treatments. The 4 dietary treatments were (1) starter diet without SBO supplement and 19% CP (NSBO-19CP), (2) starter diet without SBO supplement and 22% CP (NSBO-22CP), (3) starter diet with 3% SBO and 19% CP (SBO-19CP), and (4) starter diet with 3% SBO and 22% CP (SBO-22CP). Milk feeding value was similarly based on a constant protocol across experimental treatments and calves had ad libitum access to water and starter diets throughout the study. All calves were weaned on d 63 of age and remained in the study until d 83 of age. Calves supplemented with SBO had lower starter feed intake and average daily gain (ADG) and lower feed efficiency (FE) but had a higher fecal score indicating a higher likelihood of diarrhea occurrence compared with unsupplemented calves. Wither heights, digestibilities of organic matter, CP, and neutral detergent fiber were decreased, and ruminal volatile fatty acids tended to be reduced, and the molar proportion of ruminal butyrate (preweaning) and acetate (postweaning) reduced by supplemental SBO. The urinary allantoin and total PD excretion were reduced; however, urinary nitrogen excretion was increased when calves were supplemented with SBO. The CP amount did not affect starter feed intake, FE, or diarrhea occurrence rate, whereas the 22CP diets increased neutral detergent fiber digestibility, improved ADG (tendency), and increased allantoin and urinary PD excretion compared with the 19CP diets. The starter feed intake, ADG, FE, diarrhea occurrence rate, nutrient digestibility, and ruminal fermentation were not affected by the interaction between starter SBO and CP level; however, hip height and total PD in calves that received the SBO-22CP diets were higher than those fed the SBO-19CP diets. In conclusion, based on our experimental conditions, supplemental SBO could not be recommended for dairy calves. Furthermore, our findings indicate that SBO has negative effects on performance more attributed to reducing starter intake, digestibility, and ruminal volatile fatty acid concentration rather than because of a limitation of starter metabolizable protein supply and intestinal amino acid availability. Therefore, our results indicate that feeding the higher starter CP content is not a viable strategy to compensate for the negative effects of SBO supplementation on the growth performance of dairy calves.     

Starch–protein interaction in the rumen of weaned dairy calves

The objectives of this study were to investigate the effect of starch and protein interaction on rumen environment, in situ digestion, and total-tract digestibility of nutrients in weaned dairy calves between 8 and 16 wk of age. Sixteen rumen-cannulated calves were randomly divided into 4 dietary treatment groups with 4 calves fed in each treatment. The treatment diets had 2 levels of starch [18%, low starch (LS), or 38%, high starch (HS)] and 2 levels of protein [16%, low protein (LP), or 22%, high protein (HP)] on a dry matter (DM) basis in calf grower: (1) LPLS, (2) LPHS, (3) HPLS, and (4) HPHS. Calves were fed for ad libitum intake (95% assigned grower and 5% grass hay), and refusals were collected weekly. Total-tract digestibility collection and in situ digestibility procedures were performed for each calf at 11 and 15 wk. Samples for in situ digestibility, grass hay (GH), soybean hulls (SBH), wheat middlings (WM), ground corn (GrC), and soybean meal (SBM) were incubated for 9 and 24 h. There was no starch and protein interaction on total-tract digestibility of calves. Total-tract DM, neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibility, and feed efficiency were affected by both protein and starch inclusion level in calf diet. Total-tract starch digestibility was lower for LS diets. Dry matter digestibility and feed efficiency were greater in calves fed HP and HS diets compared with calves fed LP and LS diets, respectively. Fiber digestibility (NDF and ADF) was less in calves fed HS diets compared with calves fed LS diets but was greater in calves fed HP diets compared with calves fed LP diets. Level of protein did not affect in situ DM and NDF disappearance of GH, but HP increased in situ DM and NDF disappearance of SBH. High-starch diets decreased DM and NDF disappearance of both GH and SBH. At 20 h after feeding, ruminal pH was 0.51 unit higher in calves fed HPHS compared with calves fed LPHS. Total ruminal VFA and proportion of propionate was greater with HS versus LS, whereas proportion of acetate was greater with LS versus HS. The DM disappearance of SBM and WM and NDF disappearance of WM was greater for calves fed HPHS compared with calves fed LPHS at 11 wk of age. In our study, when HP was fed with HS, rumen pH, in situ digestion of WM and SBM, and total-tract digestion of DM, NDF, and ADF increased. This provides evidence for starch–protein interaction in the rumen of recently weaned dairy calves. Improvements in total-tract and in situ digestibility suggest that both protein and starch levels are important for 8- to 16-wk-old calves.