Effects of buffers on milk fatty acids and mammary arteriovenous differences in dairy cows fed Ca salts of fatty acids.

Ten Holstein cows in early lactation were used in a replicated 5 x 5 Latin square design to study the effects of MgO and three buffers added to diets containing Ca salts of canola oil fatty acids. Treatments were 1) control (basal diet; no buffer). 2) 1.1% NaHCO3 plus 1.1% KHCO3, 3) 1.9% NaHCO3, 4) 0.5% MgO, and 5) 2.0% Na sesquicarbonate (percentage of dry matter). The control diet contained 53% grass silage, 43% concentrate, and 4% Ca salts. Body weight, intake, milk yield, and percentages of milk fat, protein, and lactose were unaffected by treatments. Buffers and MgO tended to increase triacylglycerol extraction by the mammary gland and changed the proportions of some fatty acids in milk. Arterial concentrations of acetate and triacylglycerol were correlated with their respective arteriovenous differences. Extraction by the mammary gland was high for acetate (approximately equal to 58.2%), triacylglycerol (approximately equal to 47.3%) propionate (approximately equal to 34.6%), and glucose (approximately equal to 24.3%). Extraction of free fatty acids, phospholipids, or cholesterol was negligible. Mammary triacylglycerol arteriovenous difference tended to be higher than when MgO was fed than when NaHCO3 was fed. Sodium sesquicarbonate, NaHCO3, and the blend of bicarbonate buffers increased C18:2 in milk fat when compared with the control treatment. The concentration of C18:2 in milk fat decreased when MgO was fed, but the ratio of cis-C18:1 to trans-C18:1 increased compared with effects of dietary NaHCO3. Medium-chain fatty acids in milk fat tended to be higher than Na sesquicarbonate than with NaHCO3. Buffers and MgO modified the profiles of fatty acids in milk.

Fatty acid profile and physical properties of milk fat from cows fed calcium salts of fatty acids with varying unsaturation.

Holstein cows (n = 24) averaging 42 d in milk were used in a randomized complete block design during a 4-wk trial. A control total mixed ration (TMR) was compared with TMR supplemented with Ca salts of fatty acids from canola oil, soybean oil, or linseed oil. The three vegetable oils were progressively more unsaturated; the dominant fatty acids were, respectively, cis-delta-9-C18:1, C18:2, and C18:3. Apparent total tract digestibility of dry matter, crude protein, ether extract, and neutral detergent fiber was higher for rations containing Ca salts than for the control ration. Milk yield increased linearly as the unsaturation of the dominant fatty acid in the Ca salts increased. Milk fat percentage was reduced when Ca salts were added to the rations. The addition of Ca salts to the ration decreased the proportions of saturated fatty acids that contained C6 to C16 and increased the proportions of C18:0, cis-delta-C18:1, and trans-delta-11-C18:1 in milk fat. Proportions of C18:2 and C18:3 increased linearly, and cis-delta-9-C18:1 decreased linearly, as the unsaturation of the dominant fatty acid in the Ca salts increased. The proportion of fat that was liquid at 5 degrees C was higher for butter from cows fed diets containing Ca salts, but the proportion of liquid fat at 20 degrees C was not affected. Calcium salts of unsaturated fatty acids added to the diets of dairy cows improved the thermal properties of milk fat.

Timothy grass or alfalfa silage for cows in midlactation: effect of supplementary barley.

Twenty-four multiparous Holstein cows averaging 104 d of lactation were used in a trial with a split-plot design to evaluate the nutritive value of two silages, timothy grass or alfalfa, both treated with formic acid and stored in plastic bag silos. Silages were offered for ad libitum intake either alone or with 17 or 34% (dry matter basis) dry-rolled barley. Both silages contained similar amounts of acid detergent fiber (ADF) (27.5 and 26.7% for timothy grass and alfalfa, respectively). After 110 d of storage, alfalfa silage contained higher amounts of organic acids and NH3 N but had lower soluble N. Total dry matter intake (DMI) and silage DMI were similar between cows fed both silages. Increased barley proportion decreased silage DMI (19.2 to 14.2 kg/d). Apparent total tract digestibility of dry matter was unaffected by treatment. The digestibility of neutral detergent fiber and ADF was higher for the timothy grass silage than for alfalfa silage and was unaffected by the barley percentage added to either silage. Milk yield was lower (23.9 to 22.6 kg/d) for cows fed the highest proportion of barley. The 4% fat-corrected milk yield was unaffected by treatment. Percentages of fat, protein, and total solids in milk were higher for cows fed diets with the higher barley content. Milk fat and protein yields were similar among treatments. Urea in blood was lower for cows fed timothy grass silage than for cows fed alfalfa silage (4.68 vs. 6.23 mg/100 ml). These results suggest that timothy grass silage and alfalfa silage, when stored at a similar ADF content, have comparable nutritive value for midlactation cows.

Dietary soybeans extruded at different temperatures: milk composition and in situ fatty acid reactions.

Twenty-four multiparous Holstein cows, 4 of which were ruminally fistulated, were assigned to one of four diets containing full-fat soybeans, either raw or extruded at 120, 130, or 140 degrees C. Our hypothesis was that the extrusion of full-fat soybeans, as well as the extrusion temperature, would affect the bypass of fatty acids in the rumen and, thus, would modify the fatty acid profile of milk fat. Total mixed diets containing 23.7% soybeans (percentage of DM) were fed for 8 wk. Milk yield was lower, and the proportion of milk CP was higher, for cows fed raw soybeans than for cows fed extruded soybeans. Compared with raw soybeans, extruded soybeans increased the concentration of delta-11-trans-C18:1 from 2.72 to 11.41% in milk fat but had no effect on yield or percentage of milk fat. Polyunsaturated fatty acids of raw soybeans disappeared more rapidly than did those of extruded soybeans from bags incubated in the rumen of fistulated cows. However, more delta-11-trans-C18:1 and C18:0 appeared in bags containing extruded soybeans than in bags containing raw soybeans. Extrusion of full-fat soybeans influenced the metabolism of fatty acids in the rumen and the fatty acid profile of milk fat, but the temperature of extrusion had only minor effects on these parameters.

Lactational response of cows to different concentrations of calcium salts of canola oil fatty acids with or without bicarbonates.

Holstein cows (n = 24) averaging 39 d of lactation were used in a randomized complete block design during an 8-wk trial. From wk 1 to 4, diets contained 62% alfalfa silage and 38% concentrates (dry matter basis), and, from wk 5 to 8, diets contained 47% forage and 53% concentrates. The concentrates were increased for the second phase so that the effect of bicarbonates could be expressed more fully. Diets 1, 2, and 3 contained 2% of a blend of Na and K bicarbonates and 0, 2, or 4% of Ca salts of canola oil fatty acids (percentage of dry matter), respectively. Diet 4 contained the same percentage of Ca salts as did diet 3 but without bicarbonates. Dry matter intake decreased linearly (wk 4), and milk yield was altered quadratically (wk 4), as the percentage of Ca salts in the diet increased. Milk fat percentage (wk 8) and yield (wk 4 and 8), as well as milk protein percentage (wk 4 and 8) and yield (wk 4), decreased linearly as the percentage of Ca salts in the diet increased. Short- and medium-chain saturated fatty acids decreased linearly, and C18:0, trans-delta-11-C18:1, cis-delta-9-C18:1, cis-delta-11-C18:1, and C18:2 increased linearly, as Ca salts in the diet increased. Addition of Na and K bicarbonates to the diets that contained Ca salts increased milk and milk protein yields and increased the proportions of C18:2 in milk fat at wk 8. Dietary bicarbonates had no effect on the responses of other milk fatty acids to supplementation of 4% Ca salts of canola oil fatty acids.

Performance and profiles of milk fatty acids of cows fed full fat, heat-treated soybeans using various processing methods.

Twenty-four multiparous Holstein cows (48 d in lactation) were used in an 8-wk trial employing a completely randomized block design to determine the effect of heat treatment of full fat soybeans on the fatty acid composition of milk fat. Treatments consisted of a total mixed ration supplemented with 1) ground raw, 2) extruded, 3) micronized, or 4) roasted soybeans included at 17.5% of the dry matter of the total mixed ration. Dietary treatment had no effect on body weight, yields of milk or solids-corrected milk, fat percentage, or yield of milk fat or protein. Cows fed ground raw soybeans had a higher dry matter intake and a higher percentage of protein in milk than those fed heat-treated soybeans. The concentrations of saturated fatty acids from C8:0 to C16:0 were lower, and cis-delta-9-C18:1 tended to be higher, in the milk fat of cows fed heat-treated soybeans than in the milk fat of cows fed ground raw soybeans. The concentration of trans-delta-11-C18:1 was lowest for cows fed ground raw soybeans, intermediate for cows fed micronized and roasted soybeans, and highest for cows fed extruded soybeans. Cows fed extruded soybeans had lower concentrations of C18:2 and C18:3 than did cows fed micronized or roasted soybeans; cows fed ground raw soybeans had intermediate concentrations of C18:2 and C18:3.

Juice-extracted grass pellets and sodium bicarbonate for cows fed timothy silage of two chop lengths.

Eighteen multiparous Holstein cows in midlactation were used in a switchback design trial to evaluate the effect of chop length (3 or 30 mm) of timothy grass silage, containing less than 30% ADF and treated with formic acid, on DMI and cow performance. Within chop length, addition of NaHCO3 (2% of DMI) or the replacement of 30% of silage DM with juice-extracted grass pellets was also evaluated. Cows were fed a TMR composed of 90% silage and 10% concentrate. Silage preservation characteristics were not different between chop lengths. The DMI and apparent digestibility were similar among treatments. Yields of 4% FCM (24.9 vs. 22.7 kg/d), fat (1.03 vs. .93 kg/d), and protein (.83 vs .77 kg/d) were higher with the short chopped silage. Milk protein, milk NPN content, and serum urea were higher for cows fed long chopped silage. Yields of milk and milk constituents were not affected by the addition of juice-extracted grass pellets or NaHCO3. Fat percentage and fatty acid composition of milk remained unchanged by treatments. Reduction of particle size, from 30 to 3 mm, of timothy grass, treated with formic acid at harvest and using compaction at ensiling in bag silos, did not affect silage conservation characteristics but did improve milk, fat, and protein yields when cows were fed high silage diets.

Juice-extracted grass pellets and sodium bicarbonate for cows in midlactation fed timothy grass silage.

Eighteen midlactation Holstein cows, averaging 80 to 125 d of lactation, were used in a trial of switchback design to evaluate two timothy silages, wilted or direct-cut and treated with formic acid, and three treatments, control, NaHCO3 added at 2% of DM, or juice-extracted grass pellets replacing 30% silage DM. Cows fed direct-cut silage that had been treated with formic acid consumed more DM (19.8 vs. 18.6 kg/d) than those fed wilted silage. The DMI was also increased with NaHCO3 and grass pellet treatments. However, NaHCO3 reduced digestibility of most nutrients without affecting pH of rumen fluid or degradation of DM and NDF. Compared with wilted silage, direct-cut silage that had been treated with formic acid contained more degradable NDF (86 vs. 84.5%). Milk yield (24.9 vs. 23.6 kg/d) was higher for cows fed direct-cut than wilted silage, but 4% FCM yield remained unchanged. Addition of NaHCO3 tended to increase yields of milk and 4% FCM. Treatments did not affect milk composition. Serum urea N was higher for cows fed the direct-cut silage than for cows fed wilted silage. Silage type had more impact on feed intake and performance than did NaHCO3 or juice-extracted grass pellets.

Suppressive effect of serum from pigs and dogs fed a diet deficient in vitamin E and selenium on lymphocyte proliferation.

The effect of sera collected from either pigs or dogs previously fed a vitamin E (vit E)- and selenium (Se)-deficient diet on in vitro lymphocyte blastogenesis response to mitogens was studied. Porcine sera were obtained from pigs used in 2 different trials. In I trial, 4-wk-old pigs received either a basal diet deficient in vit E and Se or the basal diet supplemented with Vit E, Se or Vit E and Se. Pigs were maintained on their respective diet for 25 d. Canine sera were collected from pups maintained on a deficient diet for 8 wk. Four dogs and 4 pigs maintained on a commercial diet were used as donors of peripheral blood lymphocytes (PBL). The addition of sera from pigs or dogs maintained on a vit E- and Se-deficient diet markedly suppressed both porcine and canine PBL response to mitogens. Porcine PBL blastogenesis was also suppressed when porcine or canine sera were added 8, 24 or 48 h after the beginning of the incubation period to culture containing 1% of fetal bovine serum (FBS). However, the suppressive effect caused by porcine sera was less severe than the one due to canine sera. Addition of 1% FBS in the cultures was sufficient to eliminate the suppression caused by the presence of sera from pigs fed a vit E- and Se-deficient diet. Other attempts to restore the lymphocyte response to mitogens by the addition of indomethacin, diethylcarbamazine or eicosatetraynoic acid, inhibitors of prostaglandin and/or leukotriene synthesis, were not successful. Because of the severe suppression caused by sera from animals maintained on a vit E- and Se-deficient diet on the in vitro response of lymphocytes to mitogenic stimulations, it is very important to take precautions to avoid such deficiency. In vivo suppression of immunocompetent cells to antigenic stimulations may impair the capacity of the host to control infections.

Cellular immune responses in pigs fed a vitamin E- and selenium-deficient diet.

The effects of dietary restriction of vitamin E (Vit E) and selenium (Se) on lymphocyte proliferation, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC), and on burst respiratory response of stimulated granulocytes as measured by chemiluminescence (CL) were studied in pigs. Six male weanling pigs were maintained for 25 d on a torula yeast-based diet containing no measurable amount of alpha-tocopherol and less than .02 mg of Se per kilogram of feed. Six others received the same basal diet supplemented with 33 IU of DL-alpha-tocopheryl acetate and .2 mg of Se per kilogram of feed. All pigs were inoculated with Salmonella typhisuis on d 21 of the feeding period and killed on d 25. Tests to measure cellular immune functions were performed on cells isolated from blood samples taken on d 21 and 25. After 21 d of feeding, lymphocyte blastogenesis responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen in pigs fed the Vit E- and Se-deficient diet were normal compared with the response in pigs fed the supplemented diet. Moreover, the cytotoxic activity of NK cells, the ADCC response, and the CL response of granulocytes were not affected. After 25 d, a marked suppression of lymphocyte response to mitogens occurred in pigs fed the Vit E- and Se-deficient diet when the cells were cultured in the presence of autologous serum. When fetal bovine serum replaced autologous serum in the cultures, no suppression was observed. No effect on NK activity and ADCC was observed, whereas the CL peak response of granulocytes tended to be higher in pigs fed the deficient diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood responses of calves fed milk substitutes containing hydrolyzed fish protein and lime-treated corn flour.

Two experiments involving 3- to 5-d-old dairy calves were carried out. In Experiment 1, lime-treated corn flour (Nixtamal) supplied 50 to 100% of carbohydrates in a milk substitute based on sodium caseinate, lard, and cerelose. In Experiment 2, partially hydrolyzed fish protein concentrate replaced 50% of 67% of proteins in milk substitutes based on skim milk powder, lard, and 35% Nixtamal. Increasing the proportion of carbohydrates supplied by Nixtamal was associated with a linear decrease of postprandial serum glucose and insulin. Postprandial fluctuations in blood glucose were less in calves fed Nixtamal than in controls. Nixtamal probably was trapped within the casein clot in the abomasum, leading to delayed rate of passage of Nixtamal carbohydrates into the intestine. Replacing skim milk protein with hydrolyzed fish protein in diets containing Nixtamal had no effect on blood glucose or insulin but elevated free essential amino acids, which promoted glucagon secretion. More uniform concentrations of blood essential amino acids and glucose were related to lower blood urea at 54 d in calves fed diets based on hydrolyzed fish protein and Nixtamal, than that of control calves. It is suggested that more uniform postprandial blood glucose concentrations might reduce amino acid degradation for energy purposes and stimulate protein synthesis. Young dairy calves may adapt to milk substitutes based on Nixtamal and hydrolyzed fish protein despite changes in the concentration patterns of several blood components.

Survival rate and development of fetuses during the first 30 days of gestation after folic acid addition to a swine diet.

At weaning, 162 sows were assigned randomly to six treatments (27 in each treatment) according to a 2 X 3 factorial arrangement: two levels of supplementary folic acid (0 and 5 mg/kg of diet) and three treatments to stimulate ovulation (none, flushing and pregnant mare serum gonadotropin [PMSG] injection). All sows were mated twice within 7 d after weaning. Of the 162 animals originally selected, 123 sows were pregnant and used in this trial. The flushing treatment consisted of allowing sows ad libitum access to feed from the day after weaning through the 1st day of behavioral estrus, whereas control animals received 2.4 kg of feed daily. The hormonal treatment consisted of one i.m. injection of 1,250 IU of PMSG the day after weaning. The commercial-type diet used as the control was computed to contain .6 mg folates per kilogram. Folic acid supplementation elevated (P less than .001) serum folates between weaning and 30 d of gestation. Fetuses of sows fed the diet supplemented with folic acid had a higher (P less than .05) total protein concentration than fetuses of control sows, whereas RNA and DNA concentrations and protein:DNA ratio were not affected. The PMSG treatment elevated (P less than .05) ovulation rate, whereas the flushing or folic acid treatments had no effect on this trait. The addition of 5 mg/kg folic acid to the commercial-type diet improved (P less than .05) the survival rate of fetuses during early gestation and tended (P = .096) to increase the number of fetuses presumably living at 30 d of gestation when this treatment was associated with high ovulation rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum zinc, iron and copper status during early gestation in sows fed a folic acid-supplemented diet.

The purpose of this trial was to determine whether an addition of folic acid to a commercial diet would affect serum Zn, Fe and Cu status in sows between weaning and 30 d of gestation. At weaning, 162 sows were assigned randomly to six groups and housed in individual cages fitted on a slatted floor. There were six treatments according to a 2 X 3 factorial arrangement: two levels of supplementary folic acid (0 and 5 mg/kg of diet) and three treatments to stimulate ovulation (none, flushing and pregnant mare serum gonadotropin [PMSG] i.m. injection). Control groups were fed a commercial-type diet, and folic acid-treated groups were fed the same diet supplemented with 5 mg/kg of pteroylglutamic acid. All sows were mated twice within 7 d after weaning. Of the 162 animals originally selected, 123 sows were pregnant and used in this trial. Serum folates, Zn, Cu and Fe were measured at weaning, mating and 30 d of gestation. Serum Cu, Zn and folates increased between weaning and mating, and then decreased to 30 d of gestation. Supplementing the commercial diet with folic acid elevated serum folates between weaning and d 30 of gestation (P less than .001). Folic acid supplementation also was associated with a higher level of serum Zn at 30 d of gestation. Supplemental folic acid had no effect on the pattern of serum Cu and Fe throughout the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Digestibility measured by fecal and ileal collection in preruminant calves fed a clotting or a nonclotting milk replacer.

Eight Holstein male calves, each fitted with an ileal reentrant cannula at 7 to 10 d of age, were fed a milk replacer based on low heat skim milk powder with or without an oxalate-NaOH buffer known to prevent curd formation in the abomasum. The calves were used to study the effects of milk clotting on digesta flow at the ileum and apparent digestibility measured by fecal and ileal collection. Patterns of ileal flow of total digesta, DM, N, and fat were similar for the clotting and the nonclotting milk replacers. The apparent digestibility of DM and N was higher when measured by fecal than ileal collection for both milk replacers. Digestibility of DM was higher for the clotting than for the nonclotting milk replacer when measured by ileal collection. Clotting did not affect N digestibility measured by either fecal or ileal collection. The concentration of amino acids differed generally in the ileal digesta compared with concentration in feces. In the ileal digesta, some amino acids showed lower concentrations in the clotting milk replacer fed calves compared with those fed the nonclotting milk replacer. The coefficients of digestibility of each amino acid were similar when measured by either fecal or ileal collection. Clotting had no effect on amino acid digestibility measured by both fecal and ileal collection. The data suggest that fecal collection might indicate higher digestibility as compared with ileal collection and that the absence of milk replacer clotting does not affect ileal flow and digestibility of milk replacer N and fat.

Digestibility and blood parameters in the preruminant calf fed a clotting or a nonclotting milk replacer.

Eight male Holstein calves 7 to 10 d of age were fed a milk replacer containing a skim milk powder subjected to low-temperature drying either with or without addition of an oxalate-NaOH buffer known to prevent curd formation. The calves were used in a completely randomized design to study the effect of milk clotting on digestibility and blood parameters. Plasma glucose and plasma insulin were similar (P greater than .05) for the clotting and the nonclotting milk replacers. For both treatments, concentrations of glucose and insulin reached a peak 2 h postfeeding (P less than .01). Plasma triglycerides were higher (P less than .01) postfeeding for the nonclotting than for the clotting milk replacer. Plasma essential amino acids and plasma urea were higher, whereas plasma calcium was lower, for the nonclotting milk (P less than .01). Digestibility of dry matter, protein and fat was similar (P greater than .05) between clotting and nonclotting milk. The dry matter content of feces was not affected by clotting (P greater than .05). The data are interpreted to indicate that clotting of the milk replacer modifies blood concentrations of triglycerides, essential amino acids and urea without changing the digestibility of the diet.

Effect of methanol/acetone/water extraction and enzymatic hydrolysis on the nutritional value of unheated rapeseed proteins.

The objective of this work was to study the effect of the extraction of phenols by methanol/acetone/water and proteolysis (pepsin 1 hour; trypsin 2 hours) on the nutritional characteristics of unheated rapeseed protein as measured by weight gain, protein intake, net protein ratio, apparent digestibility and absorbed protein. The effect of proteolysis of the methanol/acetone/water extracted rapeseed protein, and the effect of mixing the methanol/acetone/water extract back with the extracted rapeseed protein was also studied. Extraction of phenolic compounds from rapeseed flour significantly improved weight gain, protein intake, net protein ratio and absorbed protein value. However, the mixing of phenolic extract with the extracted rapeseed protein did not appear to have a significant effect. Enzymatic hydrolysis (1 hour with pepsin and 2 hours with trypsin) of the raw material significantly improved the weight gain and protein intake. The combined methanol/acetone/water extraction and protein hydrolysis treatments were beneficial on all nutritional quality parameters of rapeseed protein. These results suggest that the protein-bound phenolic compounds, rather than the free phenolic compounds contribute mainly to the decrease in the nutritional values of proteins associated with phenolic compounds in raw flour before extraction.

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.

Duodenal flow of digesta in preruminant calves fed clotting or nonclotting milk replacer.

Four Holstein male calves each were fitted with a reentrant duodenal cannula and fed a low heat milk replacer with or without an oxalate-NaOH buffer known to prevent curd formation in the abomasum. Animals were used in a crossover design to study the effect of milk clotting on duodenal flow of DM, fat, protein, lactose, and Ca. Clotting affected the flow of DM, protein N, total N, and fat as shown by the more uniform gastric emptying of the clotting milk replacer compared with the nonclotting one. For both treatments, the flow rate of these components reached a peak 2 h after feeding. Clotting did not alter the flow rate of free amino N, lactose, and Ca. The cumulative flow of DM, lactose, and Ca was similar for the clotting and nonclotting milk replacers rising gradually during the first 4 h postfeeding and tending to plateau thereafter. The clotting milk replacer resulted in a more linear cumulative flow of fat, protein N, and total N than the nonclotting one. Proteolysis of milk protein in the abomasum was the same for the two milk replacers as indicated by the total flow of free amino N measured over 24 h. Data suggest that milk clotting modifies abomasal flow of milk constituents retained in the abomasal clot but does not alter the flow of constituents in the whey fraction.

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.

Serum folates in gestating swine after folic acid addition to diet.

Folic acid was added to the diet as a simple means to increase serum folates in gestating sows. At weaning, 95 multiparous sows were randomly assigned to five treatments. Of these sows, 67 farrowed and were used for this trial. Three supplementation levels of folic acid added to a commercial diet at 3, 9 and 27 mg per kg were studied. A commercial diet without any supplementation of folic acid was used as a control treatment. A fifth treatment consisted of eight im injections of 15 mg of folic acid each, according to a predetermined schedule that was previously effective in improving the reproductive performance of sows when combined with flushing. Each sow was kept in an individual cage and received 2 kg of feed daily. Serum folates were measured at weaning, mating and on d 14, 28, 42 and 56 after mating. The time-response curve of serum folates in sows injected with folic acid was higher than that of sows fed the unsupplemented diet (P = .057). Adding folic acid to diet may be as efficient as folic acid injections to elevate serum folates when compared with sows fed the control diet. The mean supplementary level of folic acid sufficient to maintain the serum folate concentration at approximately the same levels as those observed in sows injected with folic acid was estimated to be near 4.3 mg per kg of feed.