Using compositional mixed-effects models to evaluate responses to amino acid supplementation in milk replacers for calves.

The consequences of supplementing Lys, Met, and Thr in milk replacers (MR) for calves have been widely studied, but scarce information exists about potential roles of other AA (whether essential or not). The effects on growth performance of supplementation of 4 different AA combinations in a mixed ration (25.4% crude protein and 20.3% fat) based on skim milk powder and whey protein concentrate were evaluated in 76 Holstein male calves (3 ± 1.7 d old). The 4 MR were as follows: CTRL with no AA supplementation; PG, supplying additional 0.3% Pro and 0.1% Gly; FY, supplying additional 0.2% Phe and 0.2% Tyr; and KMT, providing additional 0.62% Lys, 0.22% Met, and 0.61% Thr. All calves were fed the same milk allowance program and were weaned at 56 d of study. Concentrate intake was limited to minimize interference of potential differences in solid feed intake among treatments. Animals were weighed weekly, intakes recorded daily, and blood samples obtained at 2, 5, and 7 wk of study to determine serum urea and plasma AA concentrations. Plasma AA concentrations were explored using compositional data analysis, and their isometric log-ratio transformations were used to analyze their potential influence on ADG and serum urea concentration using a linear mixed-effects model. We detected no differences in calf performance and feed intake. Plasma relative concentration of the AA supplemented in the KMT and PG treatments increased in their respective treatments, and, in PG calves, a slight increase in the proportion of plasma Gly, Glu, and branched-chain AA was also observed. The proportions of plasma branched-chain AA, His, and Gln increased, and those of Thr, Arg, Lys, and Glu decreased with calves' age. A specific log-contrast balance formed by Arg, Thr, and Lys was found to be the main driver for lowering serum urea concentrations and increasing calf growth. The use of compositional mixed-effects models identified a cluster formed by the combination of Arg, Thr, and Lys, as a potential AA to optimize calf growth.

Evaluating the potential role of tryptophan in calf milk replacers to facilitate weaning.

Tryptophan is a precursor of serotonin, a neurotransmitter that participates in the control of the affective state of an animal. We hypothesized that Trp supplementation could help dairy calves to cope with weaning stress. Twenty-seven Holstein male calves (48 ± 0.8 d old; 82 ± 2.6 kg of body weight) were used to evaluate the effects of Trp supplementation at a rate of 4.5 g/d via milk replacer (MR) on performance and behavioral parameters around weaning. All calves received the same feeding program (6 L/d at 15% dry matter from d 1 to 7, 4 L/d at 15% dry matter from d 8 to 14, and 2 L/d at 15% dry matter in one feeding until d 21 of study) and were completely weaned 22 d after the beginning of the study (around 70 d of life). Calves were fed a starter feed (19.3% crude protein and 16.2% neutral detergent fiber, on a dry matter basis) and chopped straw ad libitum. Animals were weighed weekly, dry matter intakes were recorded daily, lying behavior was recorded using accelerometers throughout the study, and scan sampling was performed twice a week, 1 h after the morning feeding, to record behavioral activity (nonnutritive oral behaviors, suckling a neighbor calf, standing, resting, rumination, vocalizations, eating, and drinking). Tryptophan supplementation did not affect calf performance or concentrate and MR intake, but straw intake tended to be greater in nonsupplemented compared with Trp-supplemented calves (153 vs. 129 ± 9.0 g/d, respectively). Lying time, lying bouts, and lying duration decreased when changes in the MR feeding program occurred, independent of treatment. Similarly, differences in behavioral observations occurred along days of study, with no effect of Trp supplementation. The main changes observed in calf behavior were an increase in vocalizations and standing time 1 h after the morning feeding at weaning, but again these changes were independent of treatment. Parameters measured in serum and plasma indicated an increase in Trp, kynurenine, and the kynurenine/Trp ratio after feeding in the Trp calves. A tendency for lower plasma glucose concentration after feeding was observed in the Trp group. No changes in stress markers such as cortisol and haptoglobin in serum were detected. In conclusion, supplementing 4.5 g/d of Trp via MR between 48 and 62 d of life had no effect on performance or behavior in calves around weaning.

Short communication: Performance, intestinal permeability, and metabolic profile of calves fed a milk replacer supplemented with glutamic acid.

The objective of this study was to evaluate the potential benefits of supplementing glutamic acid in milk replacers (MR) with respect to calf performance, intestinal permeability, and metabolism. Sixty Holstein male calves (3 ± 1.3 d old and 45 ± 5.9 kg body weight) were individually housed and fed a control MR without AA supplementation (24.8% crude protein and 19.1% fat, dry matter basis), or MR supplemented with 0.3% glutamic acid (25.1% crude protein and 20.3% fat, dry matter basis). Animals followed the same MR feeding program and were weaned at 56 d of the study. The amount of starter concentrate offered was restricted to limit the effect of concentrate intake on calf metabolism. Individual daily consumption and weekly body weight were measured, and 4 h after the morning feeding, blood samples were obtained at 14 and 35 d to determine general biochemical parameters and plasma AA concentrations. On d 10 of the study, we conducted an intestinal permeability test by including 21 g of lactulose and 4.2 g of d-mannitol as markers in the MR. We found no differences in calf performance or in intestinal permeability (measured as lactulose:mannitol ratio). Serum glucose concentration was greater in unsupplemented calves than in Glu-supplemented calves. At 14 d, the proportion of plasma Leu was greater in Glu-supplemented calves; the proportion of Ile tended to be greater in Glu-supplemented calves; and the proportion of Met tended to be greater in unsupplemented calves. We observed no other differences. Small changes occurred in AA metabolism when supplementing calf MR with 0.3% glutamic acid, without leading to improvements in calf performance or changes in intestinal permeability.

Behavior and inflammation of the rumen and cecum in Holstein bulls fed high-concentrate diets with different concentrate presentation forms with or without straw supplementation.

Twenty-four individually housed Holstein bulls (395 ± 7.3 kg BW and 252 ± 3.1 d age) were exposed to a 2 × 2 factorial design (meal vs. pellets; with vs. without straw) to evaluate the effect of concentrate form and provision of straw in finishing diets on behavior and expression of rumen and cecum epithelium genes related to inflammation and behavior. Concentrate and straw consumption were recorded monthly and behavior (self-grooming, social, oral nonnutritive, tongue rolling, eating, drinking, ruminating, and lying) was recorded every two weeks. Bulls were slaughtered after 64 d of exposure to treatments, lesions on the rumen and liver were assessed, and samples of the rumen and cecum were collected. Straw supplementation tended ( = 0.08) to increase concentrate intake (8.0 vs. 7.4 ± 0.26 kg/d), increased ( < 0.01) the proportion of time ruminating (9.4 vs. 3.1 ± 1.02%), and decreased ( < 0.01) the occurrence of oral nonnutritive behaviors (0.52 vs. 1.34 ± 0.123 times/15 min) relative to bulls deprived of straw. Provision of straw increased ruminal pH, but the magnitude of the change was greater when the concentrate was provided as meal compared with pellets (interaction, < 0.05). When straw was not supplemented, all rumen samples had papillae fusion, whereas only 16.7% of bulls fed pellets and straw had papillae fusions (interaction, < 0.05). Vacuole grading of the rumen papillae was less ( < 0.01) in bulls provided straw compared with bulls without straw. For the ruminal epithelium, straw provision tended to increase the relative expression ratio of (which stimulates peptide YY, PYY, and serotonin secretion; = 0.06) and α (which modulates immune reactions and behavior; = 0.09) and increased and (tight junction proteins; < 0.05), along with ß and (proinflammatory cytokines; < 0.01) and ( < 0.01) in the rumen. Moreover, it also tended to increase the relative gene expression ratio of ß (an antimicrobial peptide; = 0.10) and ( = 0.10). Bulls fed pellets had a decreased ruminal relative expression ratio of α ( < 0.05). Bulls without straw had increased ( < 0.05) the cecum relative expression ratio of ß. In conclusion, the lack of straw supplementation in bulls fed high-concentrate diets modifies behavior and affects rumen macroscopic morphology and expression of epithelial genes that could be related to behavior and inflammation.

Short- and long-term effects of forage supplementation of calves during the preweaning period on performance, reproduction, and milk yield at first lactation.

Sixty female Holstein calves [body weight (BW)=39.5±3.76kg] were fed a ground starter concentrate [19% crude protein, 19% neutral detergent fiber (NDF)] during the preweaning period. Furthermore, oats hay (68% NDF) was supplemented only during the postweaning period (CON) or during both pre- and postweaning periods (OH) to evaluate performance until first breeding, diet digestibility after weaning, reproductive performance, and milk yield at first lactation. Calves were individually housed and bedded with wood shavings. All calves were offered 6 L/d of milk replacer (MR) at 12% dry matter (DM) in 2 feedings until 28d of age, 3 L/d of MR at 12% DM in 2 feedings from 29 to 44d of age calves, and 1.5 L of MR at 12% DM in 1 feeding from 45 to 51d of age. Animals were weaned at 52d of age. Starter concentrate and forage intake were recorded daily and BW weekly until 65d of age. Two weeks after weaning, total-tract apparent digestibility was determined in 6 calves per treatment. Heifer BW was recorded at 10 mo of age. Breeding and milk yield at first lactation were also recorded. Starter concentrate intake was greater in OH compared with CON animals during the preweaning period. As a result, calves in the OH treatment had greater average daily gain (ADG) than CON animals during the preweaning period. After weaning, OH calves consumed more forage than CON animals, but we found no differences between treatments in ADG and starter concentrate intake. Similarly, total-tract apparent digestibility did not differ between treatments, and BW and ADG from 2wk after weaning to 10mo of age did not differ between treatments. Moreover, no differences in reproductive performance [age at first artificial insemination (AI), age at fertile insemination, conception rate at first AI, and number of AI] or milk yield at first lactation were observed between treatments, although a positive relationship between growth rate early in life and future energy-corrected milk yield was found. We conclude that offering forage to young calves early in life allows improvements in growth before weaning and could help in the transition to mixed diets, but the improvement in growth achieved early in life was not maintained at 10mo of age.

Arginine supplementation between 41 and 146 days of pregnancy reduces uterine blood flow in dairy heifers.

We hypothesized that arginine (Arg) supplementation during early pregnancy could foster placental vascularization. The objective of this study was to evaluate the effects of Arg supplementation on uterine artery hemodynamics between 40 and 140 days of gestation. At 41 days of gestation, 17 Holstein heifers (448 ± 73.9 kg) were surgically fitted with a catheter in the peritoneal cavity. After surgery, nine heifers received a daily intraperitoneal infusion of 40 mg of Arg/kg of body weight (BW; ARG), whereas the remaining eight heifers received a daily intraperitoneal infusion of saline solution at equivalent volumes as ARG heifers relative to BW (CTRL). Daily infusions took place every 12 hours until heifers reached 146 days of pregnancy. At 41, 62, 83, 104, 125, and 146 days of pregnancy, all heifers were body weighed, bled, and uterine blood flow volume (FV) and other hemodynamics were determined using Doppler ultrasonography. The measurements included heart rate, FV, pulsatility index, and resistance index. Plasma concentrations of amino acids (AAs), nitric oxide, glucose, insulin growth factor, progesterone (P4), growth hormone, and prolactin were analyzed. In a second experiment, we evaluated Arg metabolism when infused either intravenously or intraperitoneally. Overall, FV did not differ between the treatments, but it increased (P < 0.001) with pregnancy day. Uterine blood FV evolved differently between the treatments, with CTRL heifers having a greater (P < 0.05) FV (1104 ± 65.42 mL/min) at 146 days of pregnancy than in ARG heifers (806 ± 65.32 mL/min). Pulsatility index and resistance index decreased throughout pregnancy but did not differ between the treatments. Heart rate was decreased (P < 0.05) in ARG (74 ± 1.4 beats/min) compared with CTRL heifers (81 ± 1.5 beats/min). Plasma concentrations of Arg tended (P < 0.09) to be greater in ARG than those in CTRL heifers, but carnitine, valine, isoleucine, leucine, phenylalanine, and tryptophan were lower (P < 0.05) in ARG than those in CTRL heifers. The proportion of essential AAs (with respect to total AAs) in plasma was greater (P < 0.05) in CTRL (73 ± 2.4%) than that in ARG heifers (65 ± 2.3%). No differences between the treatments were found in plasma prolactin (P = 0.43), insulin growth factor (P = 0.97), glucose (P = 0.45), growth hormone (P = 0.39), or nitric oxide (P = 0.89) concentrations. However, plasma P4 concentration was greater (P < 0.05) in ARG than in CTRL heifers. Contrary to our hypothesis, Arg supplementation did not increase blood flow to the uterus but did change other parameters that could influence placental and fetal growth such as heart rate, maternal concentration of plasma AAs, or P4 synthesis. Furthermore, infusion sites (blood vs. peritoneum) of Arg render different metabolic responses.

Interaction between the physical form of the starter feed and straw provision on growth performance of Holstein calves.

Two experiments were conducted to assess the effect of physical form of a starter feed with or without straw supplementation on growth performance of Holstein calves. In experiment 1, a total of 32 calves were randomly assigned at 7 d of age to texturized starter feed (containing rolled barley, corn, and oats) without straw, texturized starter feed with chopped straw, and pelleted starter feed with chopped straw. All calves were offered 4 L of pasteurized whole milk twice daily from 7 to 35 d of age, 2 L of milk twice daily from 36 to 42 d of age, and 2 L of milk from 43 to 49 d of age. Animals were weaned at 50 d of age, and the study finished when calves were 63 d old. In experiment 2, a total of 60 calves (8 d of age) were randomly assigned to texturized starter feed (containing whole corn) without straw, pelleted starter feed without straw, and pelleted starter feed with chopped straw. All calves were offered the same milk replacer (MR; 23% crude protein and 19.5 fat) at 11% dry matter concentration, 4 L/d of MR until 14 d of age, 6 L/d of MR from 14 to 37 d, 3 L/d of MR from 38 to 44 d, and 1.5 L/d of MR from 45 to 52 d of age. The experiment finished when calves were 58 d old (1 wk after weaning). Rumen liquid pH was measured after weaning. In both studies, calves were individually housed in pens on sawdust bedding and starter feed and chopped straw were offered free choice in separate buckets. In experiment 1, starter feed and straw intake and growth did not differ among treatments. However, calves receiving straw showed a greater rumen pH compared with those not receiving straw. In experiment 2, pelleted started feed supplemented with straw fostered an increase in solid feed intake (as percentage of body weight) compared with a pelleted or texturized starter feed without straw supplementation. However, calves that received the texturized starter feed containing whole corn had rumen pH similar to those fed a pelleted starter feed with straw. Feeding a texturized starter feed containing rolled barley, corn, and oats (with or without straw provision) was not able to maintain rumen pH or promote growth and intake compared with offering a pelleted starter feed with chopped straw. However, when whole corn was used in the texturized starter feed, rumen pH was equivalent to that obtained with a pelleted starter feed and straw supplementation.

Cryopreservation of Galanthus elwesii Hook. apical meristems by droplet vitrification.

The aim of this study was to develop an efficient cryopreservation protocol for the geophyte giant snowdrop (Galanthus elwesii Hook.) that guarantees a high rate of survival and plant regeneration after cryopreservation. The excised apical meristems were obtained from cultures of in vitro grown bulb scales. Using a vitrification procedure and optimizing the duration of the exposure to the loading solution (LS), meristem post-rewarm survival rates higher than 90 percent were achieved. Also regrowth percentages were very high, ranging from 87 to 91 percent. After optimizing the time of exposure to the plant vitrification solution (PVS2), the survival rate was between 83 and 97 percent. During post-rewarm regeneration, good growth recovery was as high as 76 percent; however, hyperhydration and callusing were also observed. The results demonstrate that cryopreservation of Galanthus elwesii germplasm seems to be feasible.

Effect of different forage sources on performance and feeding behavior of Holstein calves.

One hundred seventy-nine Holstein male calves [44.7 kg of body weight (BW) and 8.3 d of age] participated in a series of 3 experiments to evaluate the effect of different forage sources on performance, apparent digestibility, and feeding behavior. Animals in each study were randomly assigned to 1 of 3 different dietary treatments: control (CON) calves were fed starter feed without any forage provision (this treatment was repeated in each of the 3 experiments), and the 2 other treatments consisted of the same starter feed plus a forage source: chopped alfalfa (AH) or rye-grass hay (RH) in the first study; chopped oat hay (OH) or chopped barley straw (BS) in the second study; corn silage (CS) or triticale silage (TS) in the third study. All calves were offered 2L of milk replacer (MR) at 12.5% dry matter (DM) twice daily via a bottle until 50 d of age, and 2L of MR at 12.5% DM during the week before weaning (57 d of age). The study finished when calves were 71 d old. Starter feed, MR, and forage intakes were recorded daily and BW weekly. Calves were individually housed and bedded with wood shavings. Compared with CON, animals receiving OH, TS, and BS consumed more starter feed (0.88 vs. 1.14, 1.17, 1.06 kg/d, respectively) and had greater average daily gain (0.72 vs. 0.93, 0.88, 0.88 kg/d, respectively). Animals in treatments RH, BS, CS, and TS consumed less forage (51 g/d) than AH (120 g/d) and OH (101 g/d) calves. Apparent organic matter, DM, and neutral detergent fiber digestibilities did not differ among treatments (81.5, 81.1, and 54.4%, respectively). Apparent crude protein digestibility was greater in RH, CS, and AH treatments than in CON (80.5 vs. 76.4%, respectively). Compared with CON calves, animals in the AH treatment spent less time eating starter feed and lying, animals in AH and RH treatments spent more time ruminating, with odds ratios (OR) of 5.24 and 5.40, respectively. The AH and RH calves devoted less time to performing nonnutritive oral behaviors (OR: 0.38 and 0.34, respectively), and TS calves tended to devote less time to perform nonnutritive oral behaviors (OR: 0.21) 1h after being offered MR and solid feed. In conclusion, free-choice provision of a forage source to young calves improves feed intake and performance without impairing digestibilities of DM, organic matter, crude protein, and neutral detergent fiber, and, depending on forage source, reduces nonnutritive oral behaviors and stimulates rumination.

Effect of vitamin A restriction on performance and meat quality in finishing Holstein bulls and steers.

Twenty-four Holstein steers and 23 Holstein bulls (initial body weight= 252 ± 3.5 kg and age= 187 ± 7.5d) were randomly allocated to 4 treatments arranged in a 2 × 2 factorial design with gender (bulls vs steers) and vitamin A supplementation (either restricted at 1.3 × 1000 IU/kg, VAR, or supplemented at 4.6 × 1000 IU/kg, CTR) to evaluate the effect of vitamin A restriction on performance, carcass and meat quality traits of Holstein steers and bulls. Intramuscular fat was less (P<0.01) in bulls than in steers, and tended (P=0.09) to be greater in VAR than in CTR animals. Oxidative stability tended (P=0.09) to be greater in meat from VAR than from CTR animals at 21 d of ageing. Vitamin A restriction in Holstein bulls does not achieve the same intramuscular fat levels obtained with castration.

Effects of ring castration with local anesthesia and analgesia in Holstein calves at 3 months of age on welfare indicators.

Forty-seven Holstein calves (130 +/- 3.43 kg of BW and 95 +/- 1.5 d of age) were randomly assigned to 2 treatments [intact (INT), n = 23; or castrated (CAS), n = 24] to evaluate the effect of ring castration at 3 mo of age on welfare indicators. Castration was performed with local anesthesia (2% lidocaine, 3 mL in each testis and 2 mL in the scrotum) and analgesia (flunixin meglumine, intramuscularly, 3 mg/kg of BW). No local anesthesia or analgesia was used with INT calves. Serum cortisol concentration was determined at -120, 0, 30, 60, 90, and 180 min with respect to castration. At d 0, 1, 3, 7, 14, 21, 28, 35, 42, and 49, serum haptoglobin concentration was determined, rectal body and scrotal temperatures were measured, lesions at the castration site were scored, and the activity and behavior of 18 calves (9 INT and 9 CAS) were recorded continuously for 24 h. Weekly BW and concentrate and straw DMI were recorded. To evaluate humoral immunity, at 14 d after castration, ovalbumin was injected subcutaneously and serum antibody titers against ovalbumin before the injection and at d 35 were determined. At d 49 after castration, calves were intravenously injected with ACTH, and at 0, 1, 2, and 4 h thereafter, serum cortisol and testosterone concentrations were determined. Average daily gain was greater (P < 0.001) in INT than CAS calves (1.36 vs. 1.16 +/- 0.038 kg/d, respectively). Area under the curve of cortisol at castration day was reduced (P < 0.05) in CAS calves compared with INT calves (18 vs. 33 +/- 5.2 nmol/L per hour, respectively). The main scrotal lesion score observed in CAS calves throughout the study was 0, corresponding to no visible swelling, inflammation, or infection. However, scrotal lesion scores classified as 1 (swelling) were greater (P < 0.01) at 21 and 28 d after castration than at 1, 3, 7, and 14 d. Abnormal standing occurred more frequently (P < 0.001) in CAS than INT calves (2.6 vs. 0.5 +/- 0.03%, respectively) from 3 to 14 d after castration. Head turning tended (P = 0.06) to be greater at d 14 of the study in CAS than INT calves (3.0 vs. 2.6 +/- 0.04%, respectively). At d 49, 100% of CAS calves had no testes and no serum testosterone was detected. In summary, ring castration of Holstein calves performed at 3 mo of age with local anesthesia and analgesia decreased ADG and affected some behavioral traits during the first 14 d after castration. However, intake, serum cortisol and haptoglobin concentrations, rectal temperature, and humoral immunity were not altered.

Effects of extruded linseed supplementation on n-3 fatty acids and conjugated linoleic acid in milk and cheese from ewes.

The objective of this study was to assess the effects of dietary supplementation of extruded linseed on animal performance and fatty acid (FA) profile of ewe milk for the production of n-3 FA- and conjugated linoleic acid-enriched cheeses. A Manchega ewe flock (300 animals) receiving a 60:40 forage:concentrate diet was divided into 3 groups supplemented with 0, 6, and 12 g of extruded linseed/100 g of dry matter for the control, low, and high extruded linseed diets, respectively. Bulk and individual milk samples from 5 dairy ewes per group were monitored at 7, 14, 28, 45, and 60 d following supplementation. Manchego cheeses were made with bulk milk from the 3 treatment groups. Milk yield increased in dairy ewes receiving extruded linseed. Milk protein, fat, and total solids contents were not affected by linseed supplementation. Milk contents of alpha-linolenic acid increased from 0.36 with the control diet to 1.91% total FA with the high extruded linseed diet. Similarly, cis-9 trans-11 C18:2 rose from 0.73 to 2.33% and its precursor in the mammary gland, trans-11 C18:1, increased from 1.55 to 5.76% of total FA. This pattern occurred with no significant modification of the levels of trans-10 C18:1 and trans-10 cis-12 C18:2 FA. Furthermore, the high extruded linseed diet reduced C12:0 (-30%), C14:0 (-15%) and C16:0 (-28%), thus significantly diminishing the atherogenicity index of milk. The response to linseed supplementation was persistently maintained during the entire study. Acceptability attributes of n-3-enriched versus control cheeses ripened for 3 mo were not affected. Therefore, extruded linseed supplementation seems a plausible strategy to improve animal performance and nutritional quality of dairy lipids in milk and cheese from ewes.

Effect of plant extract supplementation on Escherichia coli O157:H7 and Salmonella carcass isolation in young Holstein bulls fed a high-concentrate diet.

Ninety Holstein bulls were used in a complete randomized design to study the effect of a blend of plant extract (PE) supplementation on jejunum, cecum, and rectum microbiota (Escherichia coli and lactic acid bacteria [LAB]) and hide and carcass contamination (identification of E. coli O157:H7 and Salmonella). Three treatments--control (CTR), monensin (MON), and PE--were tested. Bulls were offered straw and concentrate ad libitum during 108 d. In the cecum, the percentage of LAB counts below 5 log CFU/ml was greater (P < 0.01) in MON (68.1%) than in CTR (34.6%) and PE (28.0%) treatments. On hide, Salmonella was detected (P < 0.05) in CTR (13.3%) and MON (10.0%) treatments, in contrast to PE (0%) treatment. In bulls fed high-concentrate diets supplemented with PE, no increase of carcass E. coli O157:H7 and Salmonella identification was observed.

Effects of crude glycerin supplementation on performance and meat quality of Holstein bulls fed high-concentrate diets.

Forty-eight bulls (335 +/- 8.6 kg of initial BW) were randomly assigned to 4 glycerin levels (0, 4, 8, and 12% of concentrate DM) with the objective of evaluating the effects of glycerin supplementation on performance, ruminal fermentation, metabolism, and carcass and meat quality in Holstein bulls fed high-concentrate diets. Concentrates were formulated to be isonitrogenous and isocaloric (assuming a glycerin ME content of 3.47 Mcal/kg of DM). Concentrate and straw were fed for ad libitum intake. Bull BW and feed consumption were recorded monthly. Additionally, rumen and blood samples were collected every month. Bulls were slaughtered after 91 d of study (460 +/- 11 kg of final BW). Hot carcass weight, carcass backfat, and conformation were recorded. The area, Warner-Bratzler shear force, and intramuscular fat content of LM were determined. Glycerin level did not affect daily concentrate intake (6.89 +/- 0.34 kg/d of DM), straw intake (1.38 +/- 0.069 kg/d of DM), total DMI (8.27 +/- 0.32 kg/d of DM), ADG (1.36 +/- 0.087 kg/d), or G:F (0.17 +/- 0.009). Similarly, rumen molar proportions of propionic, acetic, and butyric acids, and rumen liquid osmolality were unaffected by treatment. However, a decreased rumen pH (P < 0.05), and greater rumen total VFA concentration (P = 0.09), serum insulin concentration (P < 0.05), and insulin to glucose ratio (P < 0.05) were observed in bulls fed 8% glycerin in concentrate compared with those receiving 0, 4, or 12%. No changes were observed in carcass and meat quality. The ME content of glycerin (86% glycerol) can be assumed to be 3.47 Mcal/kg of DM in Holstein bulls fed high-concentrate diets. In addition, feeding concentrate containing up to 12.1% of glycerin does not lead to detrimental effects on performance, ruminal fermentation, metabolism, and carcass and meat quality variables.

Evaluation of the fermentation dynamics of soluble crude protein from three protein sources in continuous culture fermenters.

Eight dual-flow continuous culture fermenters (1.03 +/- 0.05 L) were used to assess differences in microbial degradation of the soluble CP fraction of canola meal (CMSCP), soybean meal (SBMSCP), and fish meal (FMSCP) using a completely randomized design with two 9-d experimental periods and a solution of tryptone as a control treatment (control). All fermenters received the same basal diet (58% ground corn, 40% canary grass hay, 0.4% vitamin-mineral premix, 1% CaCO(3), 0.6% salt on a DM basis) in 8 equal portions daily. During sampling on the last 3 d of each period, 90-mL doses containing soluble CP were infused into the fermenters 30 min after the beginning of the first and last feedings of the day. The total amount of soluble CP supplied by the infusions of FMSCP, CMSCP, and SBMSCP was 3.2 g/d, representing 24% of the daily dietary CP intake. Infusion of FMSCP resulted in the greatest (P < 0.05) NH(3)-N concentration (4.6 +/- 0.40 mg/dL) compared with the other treatments (0.5 +/- 0.40 mg/dL). Microbial N flow (g/d) from the fermenters was also greatest (P < 0.05) with FMSCP (1.42 +/- 0.062) compared with the other soluble CP fractions (1.08 +/- 0.062). The efficiency of microbial protein synthesis tended to be lowest with the control diet, and the efficiency of N utilization was lowest with FMSCP treatment. These results indicate that N was limiting microbial growth in the control diet, and there was more rumen-available N with the FMSCP diet compared with the other dietary treatments. The extent of degradation of the soluble CP fraction from fish meal, soybean meal, and canola meal was determined to be 99, 30, and 37% of soluble CP, respectively. These results indicate that the soluble CP fraction is not 100% degraded in all feeds and that assuming a high degradation extent of the soluble CP fraction from soybean meal and canola meal may result in an underestimation of the supply of undegradable protein from these protein sources.

Effect of a diet enriched in whole linseed and sunflower oil on goat milk fatty acid composition and conjugated linoleic acid isomer profile.

The aim of the present research was to study changes in milk composition and fatty acid profile, specifically conjugated linoleic acid (CLA) and its isomers, in goat milk as affected by dietary supplementation of sun-flower oil and whole linseed (0.81 and 1.84% of dry matter on basal diet, respectively) and to assess the persistency of the response. To achieve this objective, bulk milk from a herd and from 6 individual dairy goats fed a diet supplemented with sunflower oil and whole linseed was monitored for a period of 3 mo. Gas chromatography and silver ion HPLC were used to analyze total CLA content and the isomeric profile of these fatty acids, respectively. The contents of alpha-linolenic acid increased from 0.35% with the reference diet to 0.62% with the supplemented diet. Similarly, CLA milk content increased from 0.46 to 1.18%. The same pattern was also observed for trans-11 C18:1 (1.38 to 4.05%, respectively) in goat milk after 3 mo of lipid supplementation. In contrast, changes in other trans C18:1 isomers were less remarkable. There was a strong linear correlation between cis-9, trans-11 C18:2, the main CLA isomer, and trans-11 C18:1 under the conditions assayed and their concentration remained stable throughout the duration of the study. Levels of the minor CLA isomers were also enhanced as a consequence of lipid supplementation. The most remarkable increases were observed for 11-13 (trans-trans and trans-cis geometric isomers), whereas trans-7, cis-9 (the second most important CLA isomer from a quantitative point of view) and trans-10, cis-12 increased only slightly with lipid supplementation.

Effects of physical form of a starter for dairy replacement calves on feed intake and performance.

One hundred six female Holstein calves [body weight (BW) = 41.5 +/- 0.37 kg and 11.2 +/- 0.3 d old] were used to evaluate the effects of physical form of a starter on animal performance and starter intake. Calves were randomly allocated to 2 treatments consisting of either a multiparticle or a pelleted starter. Both starters had exactly the same ingredient and nutrient composition but differed in their physical form. Calves received 4 L/d of the same milk replacer at a 150 g/kg dilution rate in 2 offers of 2 L each until they consumed an average of 300 g/d of starter (as fed) for 2 consecutive days; then the dilution rate was decreased to 120 g/kg until the age of 49 d when milk replacer was limited to 1 daily dose of 2 L until 57 d of age. Calves were kept in individual hutches for at least 1 wk after weaning. Body weight was measured at the beginning of the study and at 49 and 64 d of age. The median perimeters for the multiparticle and pelleted starters were 0.61 +/- 0.016 and 2.71 +/- 0.082 cm, respectively. Overall starter consumption was greater in calves receiving the multiparticle starter (944.8 +/- 30.01 g/d) than in those receiving the pelleted starter (863.9 +/- 32.04 g/d). There were no differences in the total milk replacer intake between the 2 treatments. Calf BW when leaving the individual hutches at the end of the study was similar between both treatments. Consequently, feed conversion efficiency was greater in calves consuming the pelleted than the multiparticle starter up to 64 d of age, mainly due to the greater conversion efficiency obtained with the pelleted than with the multiparticle starter after the preweaning period. It is concluded that pelleted starters may result in lower dry feed consumption compared with multiparticle starters, but because final BW was similar in both treatments, feed efficiency of calves consuming pelleted starters may be greater than that of calves consuming multiparticle starters. Therefore, when feeding a starter with similar nutrient composition to the one used in this study, there seems to be an economic advantage associated with feeding the starter in a pelleted form compared with a multiparticle form.

Nitrogen metabolism in the rumen.

Protein metabolism in the rumen is the result of metabolic activity of ruminal microorganisms. The structure of the protein is a key factor in determining its susceptibility to microbial proteases and, thus, its degradability. Ruminal protein degradation is affected by pH and the predominant species of microbial population. Ruminal proteolytic activity decreases as pH decreases with high-forage dairy cattle-type rations, but not in high-concentrate beef-type rations. Accumulation of amino acid (AA) N after feeding suggests that AA uptake by rumen microorganisms could be the limiting factor of protein degradation in the rumen. In addition, there are several AA, such as Phe, Leu, and Ile, that are synthesized by rumen microorganisms with greater difficulty than other AA. The most common assessment of efficiency of microbial protein synthesis (EMPS) is determination of grams of microbial N per unit of rumen available energy, typically expressed as true organic matter or carbohydrates fermented. However, EMPS is unable to estimate the efficiency at which bacteria capture available N in the rumen. An alternative and complementary measure of microbial protein synthesis is the efficiency of N use (ENU). In contrast to EMPS, ENU is a good measurement for describing efficiency of N capture by ruminal microbes. Using EMPS and ENU, it was concluded that optimum bacterial growth in the rumen occurs when EMPS is 29 g of bacterial N/kg of fermented organic matter, and ENU is 69%, implying that bacteria would require about 1.31 x rumen-available N per unit of bacterial N. Because the distribution of N within bacterial cells changes with rate of fermentation, AA N, rather than total bacterial N should be used to express microbial protein synthesis.

Nitrogen metabolism of early lactation cows fed diets with two different levels of protein and different amino acid profiles.

Four multiparous Holstein cows (569+/-122 kg) surgically prepared with indwelling catheters in the mesenteric, portal, and hepatic veins and carotid artery were allocated in a 4 x 4 Latin square to determine the effects of dietary crude protein (CP) level and amino acid (AA) profile on N metabolism during early lactation (from 25 to 65 d in milk). Cows received their diets in two equal meals and were milked twice daily. The dietary treatments were: 18% CP with a high (18H) or a low (18L) quality AA profile, and 15% CP with a high (15H) or a low (15L) quality AA profile. The four diets were similar in net energy for lactation (1.75 NEL Mcal/kg) and contained the same amount of RUP (34% of CP). The quality of the AA profile pertained only to the essential AA (EAA), and was assessed by comparison with the EAA profile of casein and considered the potential contribution of EAA from ruminal bacteria. The 18H and 15H diets were supplemented with 50 and 25 g/d of ruminally protected Met, respectively. After 10 d on treatment, a blood flow marker (p-amino-hippurate) was infused into a mesenteric vein, and arterial, portal, hepatic, and mammary blood samples were obtained at 3, 6, and 12 h after feeding. Dry matter intake was similar across treatments (23.4+/-0.5 kg/d). Amino acid oxidation, and consequent urea production, in the liver were numerically greater with the 18% CP rations, and, as a result, arterial urea concentrations were greatest (P < 0.01) with these rations. The amount of total AA extracted by the mammary gland tended to be greater with the H than with the L diets (21.4 vs. 18.2 mmol/ h, respectively). Milk yield tended to be greater (P = 0.16) with the 18H and 15H diets (47.7 and 46.3 kg/d, respectively) compared with the 18L and 15L diets (45.9 and 44.6 kg/d, respectively). Also, milk CP and casein contents were greatest (P = 0.09) with the H diets compared with the L diets. Milk and plasma urea N were greatest (P < 0.01) with the 18% CP diets. The efficiency of N utilization for milk protein synthesis was greatest (P < 0.09) with the 15% CP diets. It is concluded that milk protein production during early lactation is less susceptible to variations in dietary CP contents than variations in the AA profile of the dietary protein.

Abnormal flow volume loops in patients with intrathoracic Hodgkin's disease.

STUDY OBJECTIVES: To study the incidence of upper airway obstruction, as measured on the flow volume loop (FVL), in patients with bulky mediastinal Hodgkin's disease; to correlate the FVL with CT of the chest; and to follow the changes in the FVL after treatment of the tumor. DESIGN: Retrospective study of pulmonary function tests (PFTs) and chest CTs performed as part of a clinical trial for Hodgkin's disease. SETTING: Memorial Sloan-Kettering Cancer Center, a comprehensive cancer care center. PATIENTS: Twenty-five patients (15 men and 10 women; age range, 20 to 57 years) with bulky mediastinal Hodgkin's disease enrolled in a clinical trial of chemotherapy followed by external beam radiation therapy. MEASUREMENTS AND RESULTS: Fourteen of 25 patients (56%) had an abnormal FVL prior to therapy; after chemotherapy, only 7 of 25 patients (28%) had an abnormal FVL. The abnormal patterns seen were either those typical of fixed obstruction or variable extrathoracic obstruction. No patient had a pattern typical of variable intrathoracic obstruction. On chest CT scan, 16 patients had grade-I tracheal deformity; 6 had grade-II deformity, and 3 had grade-III deformity. All three patients with grade-III deformity had a fixed obstruction pattern, as did three patients with a grade-I pattern. Patients with a fixed pattern on FVL had significant decreases in inspiratory and expiratory flow rates. CONCLUSION: FVL abnormalities suggesting upper airway obstruction occurred in > 50% of patients with bulky mediastinal Hodgkin's disease. A fixed pattern of obstruction was associated with the lower flow rates and severe tracheal distortion on CT; these patients may warrant special attention prior to general anesthesia or invasive procedures. Asymptomatic patients with abnormal FVLs but normal tracheal profiles need not undergo extensive evaluation. No patients showed the expected pattern typical of intrathoracic obstruction, but rather the major effect was on the inspiratory loop. The authors speculate on the mechanism for this unexpected finding.