A 120-d finishing study utilizing 318 heifers (342 kg initial BW) was conducted to examine effects of ruminally protected choline (RPC) in diets containing graded concentrations of tallow. Heifers ...were blocked according to previous nutrition (full-fed or limit-fed) and allotted to 24 pens containing 11 to 15 heifers. Two pens, one within each block, were assigned to each of 12 factorially arranged treatments including dietary tallow (0, 2, or 4%) and supplemental RPC (0, 20, 40, or 60 g of product daily, estimated to supply 0, 5, 10, or 15 g/d choline postruminally). Heifers were implanted with Revalor-H and fed a finishing diet based on steam-flaked and dry-rolled corn (12.5% CP, 8% alfalfa on DM basis). Dry matter intake decreased (P < 0.10) by 5.4% when tallow was increased from 0 to 4% but was not affected by RPC. Heifers receiving 4% tallow had 7.3% lower gains than those receiving none (P < 0.10). Supplementation of RPC increased (P < 0.10) ADG, with 20 g/d resulting in an 8.6% increase. Similarly, gain efficiency improved (P < 0.10) by 7.6% with addition of 20 g/d RPC. Yield grade and kidney, pelvic, and heart fat both increased linearly (P < 0.10) with fat supplementation. The percentage of carcasses grading USDA Choice was not affected by intermediate levels of RPC but decreased with the highest level (60 g/d). Dressing percentage, hot carcass weight, marbling, and 12th-rib fat thickness were not affected significantly by either tallow or RPC. On d 90, jugular blood was collected from all heifers at 2 h postfeeding. Plasma urea and serum insulin concentrations were not affected by either tallow or RPC. Dietary tallow linearly increased (P < 0.10) NEFA, cholesterol, triglyceride, and total amino acid concentrations. Choline supplementation led to quadratic responses for total amino acids (P < 0.10), with concentrations being greatest for intermediate levels of RPC. Moderate levels of supplemental RPC improved growth performance of finishing cattle without negatively affecting carcass characteristics. Optimum performance was achieved with 20 g of product daily.
Ruminally cannulated Rambouillet wether lambs were used in three 6 x 6 Latin square experiments (n = 6/experiment) to determine which essential AA limit N retention. Lambs (BW = 36.9 ± 1.9 kg for ...Exp. 1, 35.1 ± 1.4 kg for Exp. 2, and 46.0 ± 1.3 kg for Exp. 3) were housed in metabolism crates and limit-fed (DMI = approx. 1.8% of BW daily) twice daily a soybean hull-based diet low in ruminally undegradable protein. Treatments for Exp. 1 were continuous abomasal infusions of a solution (500 mL/d) containing 1) no AA (CON), 2) a mixture of 10 essential AA and 2 nonessential AA (10EAA), 3) 10EAA with Met removed, 4) 10EAA with Lys removed, 5) 10EAA with His removed, and 6) 10EAA with Thr removed. Treatments for Exp. 2 were abomasal infusions of 1) CON, 2) 10EAA, 3) 10EAA with Leu, Ile, and Val removed (-BCAA), 4) 10EAA with Arg removed, 5) 10EAA with Phe removed, and 6) 10EAA with Trp removed. Treatments for Exp. 3 were abomasal infusions of 1) CON, 2) 10EAA, 3) -BCAA, 4) 10EAA with Leu removed, 5) 10EAA with Ile removed, and 6) 10EAA with Val removed. All lambs received continuous infusions of acetate and propionate into the rumen and dextrose into the abomasum to supply additional energy. Periods were 7 d: 3 d for adaptation to abomasally infused treatments and 4 d for fecal and urinary collections. Blood samples were collected 3 h after feeding on d 7. In all 3 experiments, N retention was greater (P < 0.10) for lambs receiving 10EAA vs. CON, demonstrating that the basal AA supply from CON was limiting. Removal of each of the essential AA from 10EAA decreased (P < 0.10) their concentrations in plasma (except for Trp), indicating that 10EAA supplied these AA in excess of the animal's requirement. In Exp. 1, N retention (g/d) decreased (P < 0.10) in response to the removal of Met and Thr, but was not affected by removal of Lys and His from 10EAA. In Exp. 2, N retention decreased (P < 0.10) in response to removal of all 3 branched-chain AA, Arg, and Trp, whereas the removal of Phe from 10EAA did not affect N retention. In Exp. 3, N retention decreased (P < 0.10) in response to removal of branched-chain AA and Val, but was not affected by the omission of Leu and Ile from 10EAA. The results of this research demonstrated that Met, Thr, Arg, Trp, and Val limited N retention of lambs fed a diet low in ruminally undegradable protein. PUBLICATION ABSTRACT
Abstract
Crude glycerin (GLY) is used as an energy supplement for cattle and has been shown to increase propionate and decrease acetate concentrations in the rumen. Glycerin also decreases ruminal ...NH3, and therefore, we hypothesized that GLY in rumen fluid would decrease protein degradability of feedstuffs. The objective was to evaluate the effect of GLY in bovine rumen fluid on extent of protein degradability of alfalfa hay (ALF), dried distiller’s grains (DDG), and soybean meal (SBM). The study was conducted using an in vitro incubator with four incubation jars. Each incubation jar contained 18 filter bags with 0.5 g of ground feed sample (six bags contained ALF, six contained DDG, and six contained SBM), six blank bags, 1,600 mL of buffer solution, 400-mL rumen fluid (collected from two ruminally cannulated cows), and one of the two treatments. Treatments were 12.7 g of deionized water (−GLY) or 12.7 g of GLY (+GLY) added to the 2-liter contents of each jar. Incubation jars were purged with CO2 and allowed to incubate at 39°C for 48 h. The 48-h incubation period was repeated for a total of three runs (the study was a randomized complete block design). Fluid samples from incubation jars were collected at 0 and 48 h into 25-mL vials for measurement of pH and analysis of VFA and NH3. At the end of the 48-h incubation period, filter bags containing feed samples were collected for determination of DM, NDF, and CP disappearance. The pH and NH3 concentrations of the contents of jars were lower (P ≤ 0.01) and total VFA concentrations were greater (P < 0.01) for +GLY than −GLY after 48 h of incubation. Molar percentages of acetate, isobutyrate, and isovalerate were lower (P < 0.01) and molar percentages of propionate and valerate were greater (P ≤ 0.02), resulting in a lower (P < 0.01) acetate-to-propionate ratio for +GLY compared with −GLY after the 48-h incubation period. A GLY × feed interaction (P < 0.01) occurred for DM and CP disappearance, where +GLY decreased DM and CP disappearance of SBM more than that of ALF and DDG. Disappearance of NDF from ALF, DDG, and SBM was lower for +GLY compared with −GLY (GLY; P < 0.01). These results suggest that supplementing glycerin to ruminants may cause an increase in RUP fraction escaping to the small intestine for potential digestion and absorption.
Five ruminally cannulated Holstein steers (176 kg) were used in a 5 x 5 Latin square to evaluate the effects of branched-chain AA supplementation on N retention and plasma AA concentrations of ...steers. Steers were limit-fed (3.0 kg/d of DM) twice daily diets low in ruminally undegradable protein (72% soybean hulls, 19% alfalfa, 5% molasses, and 4% vitamins and minerals). Acetate (400 g/d) was continuously infused into the rumen. Treatments were continuous abomasal infusions of 1) 115 g/d of a mixture of 10 essential AA designed to exceed the steers' requirements (10AA), 2) 10AA with Leu removed, 3) 10AA with Ile removed, 4) 10AA with Val removed, and 5) 10AA with all three branched-chain AA removed. Experimental periods were 7 d, with 3 d for adaptation to treatments and 4 d for total fecal and urinary collections for N balance. Blood samples were collected 5 h after feeding on d 7. Retained N decreased in response to removal of Leu (P < 0.06), Val (P < 0.05), or all three branched-chain AA (P < 0.05). Plasma Leu concentrations decreased (P < 0.05) in response to removal of Leu and all three branched-chain AA. Plasma Ile concentrations decreased (P < 0.05) in response to removal of Ile and all three branched-chain AA but increased (P < 0.05) in response to removal of Leu. Plasma Val concentrations decreased (P < 0.05) in response to removal of Val and all three branched-chain AA but increased (P < 0.05) in response to removal of Leu. Responses in N balance and plasma AA concentrations of growing cattle limit-fed soybean hull-based diets demonstrate limitations in the basal supply of Leu and Val but not Ile provided that supplies of all other essential AA are met.
A study was conducted to evaluate Met requirements of late-gestation beef cows consuming low quality forages on the premise that inadequate supply of metabolizable AA may limit protein accretion ...during pregnancy. Five ruminally cannulated, multiparous late-gestation beef cows (490 ± 27 kg), of predominantly Angus (≥75%) with Hereford and Simmental breeding, were used in a 5 × 5 Latin square experiment to evaluate the effects of postruminal DL-Met supplementation on N retention, serum metabolites, and plasma AA concentrations during the third trimester of pregnancy. The basal diet was fed individually, and weights of refusals were recorded for N intake determination. Treatments consisted of no urea, urea (0.053 ± 0.002 g/kg of BW daily), urea + 5 g of Met/d, urea + 10 g of Met/d, and urea + 15 g of Met/d. Cows were adapted to the experimental diet 30 d before the beginning of the study, with periods lasting for 14 d; 4 d to allow for clearance of the previous treatment effects, 4 d for adaptation to the treatments, and 6 d for total fecal and urine collection. Blood samples were collected every 4 h on d 13 of each period for analysis of serum metabolites and plasma AA. Inclusion of urea increased DM and OM intakes (urea vs. no urea; P = 0.05), but no further improvement in intake was observed with inclusion of Met. Serum urea concentrations increased with inclusion of urea (P = 0.03) and responded quadratically (P = 0.06) when Met was added, with the lowest concentration observed in the urea + 5 g of Met/d treatment. More N was retained with the inclusion of urea (P = 0.04), and N retention increased linearly (P = 0.07) with inclusion of Met. Plasma Met concentration increased linearly (P < 0.01) with inclusion of Met. These data suggest that Met was a limiting AA and that supplementation of a combination of urea and 5 g/d of rumen-protected Met to low quality, forage diets will improve N retention and promote protein accretion during late pregnancy. PUBLICATION ABSTRACT
Resistance to carbapenems in human pathogens is a growing clinical and public health concern. The carbapenems are in an antimicrobial class considered last-resort, they are used to treat human ...infections caused by multidrug-resistant Enterobacterales, and they are classified by the World Health Organization as ‘High Priority Critically Important Antimicrobials’. The presence of carbapenem-resistant Enterobacterales (CREs) of animal-origin is of concern because targeted studies of Canadian retail seafood revealed the presence of carbapenem resistance in a small number of Enterobacterales isolates. To further investigate this issue, a risk profile was developed examining shrimp and salmon, the two most important seafood commodities consumed by Canadians and Escherichia coli, a member of the Enterobacterales order. Carbapenem-resistant E. coli (CREc) isolates have been identified in shrimp and other seafood products. Although carbapenem use in aquaculture has not been reported, several classes of antimicrobials are utilised globally and co-selection of antimicrobial-resistant microorganisms in an aquaculture setting is also of concern. CREs have been identified in retail seafood purchased in Canada and are currently thought to be uncommon. However, data concerning CRE or CREc occurrence and distribution in seafood are limited, and argue for implementation of ongoing or periodic surveillance.
We evaluated the optimal level of alfalfa inclusion in soybean hull-based diets. In Exp. 1, 20 Holstein steers (319 kg of BW) were used in a complete block design. Treatments included a soybean hull ...mix (95.7% soybean hulls, 3% molasses, 0.5% urea, 0.8% mineral mix; DM basis) fed alone (100:0) or with 10.4, 20.7, or 30.9% (DM basis) coarsely chopped alfalfa hay (90:10, 80:20, and 70:30, respectively) or alfalfa alone (0:100). Diets were fed once daily at 1.75% (DM basis) of BW. In some cases, orts were present, which caused DM, OM, and NDF intakes to decrease (linear, P < 0.05) as alfalfa was added to the diets. Digestibilities of DM, OM, and NDF decreased linearly (P < 0.05) as alfalfa was added to the diets, but quadratic responses (P < 0.05) indicated that positive associative effects occurred between soybean hulls and alfalfa. Liquid dilution rates increased (linear, P < 0.05) with alfalfa additions to the diets and also demonstrated positive associative effects between soybean hulls and alfalfa (quadratic, P < 0.05). Solid passage rates were similar for 100:0 and 0:100 but were increased (quadratically and cubically, P < 0.05) when combinations of soybean hulls and alfalfa were fed. In Exp. 2, in vitro NDF digestibilities were measured for soybean hulls, alfalfa, and a blend of 85% soybean hulls and 15% alfalfa, each with no N source or supplemented with casein or urea to ascertain the effects of protein from alfalfa on digestibility. Disappearances were increased (P < 0.05) by addition of urea or casein, but no interactions between substrate and N supplement were observed. Addition of 30% alfalfa to diets consisting primarily of soybean hulls led to positive associative effects on diet digestibility, but alfalfa additions led to increased liquid and solid passage rates, suggesting that the benefit was not a result of slower passage of soybean hulls from the rumen.
Cycling (n = 16) and noncycling (n = 24), early postpartum, suckled beef cows of three breeds were assigned randomly to three treatments: 1) 100-micrograms injection of GnRH plus a 6-mg implant of ...norgestomet administered on d -7 before 25 mg of PGF(2alpha) and implant removal on d 0 (GnRH+NORG); 2) 100 micrograms of GnRH given on d -7 followed by 25 mg of PGF(2alpha) on d 0 (GnRH); or 3) 2 mL of saline plus a 6-mg implant of norgestomet administered on d -7 followed by 25 mg of PGF(2alpha) and implant removal on d 0 (NORG). All cows were given 100 micrograms of GnRH on d +2 (48 h after PGF(2alpha)). Blood sera collected daily from d -7 to d +4 were analyzed for progesterone and estradiol-17beta, and ovaries were monitored daily by transrectal ultrasonography to assess changes in ovarian structures. Luteal structures were induced in 75% of noncycling cows in both treatments after GnRH, resulting in elevated (P < .01) progesterone on d 0 for GnRH+NORG-treated cows. Concentrations of estradiol-17beta (P < .01) and LH (P < .05) were greater on d +2 after GnRH for cows previously receiving norgestomet implants. Pregnancy rates after one fixed-time AI at 16 h after GnRH (d +2) were greater (P < .05) in GnRH+NORG (71%) than in GnRH (31%) and NORG (15%) cows. Difference in pregnancy rate was due partly to normal luteal activity after AI in over 87% of GnRH+NORG cows and no incidence of short luteal phases. The GnRH+NORG treatment initially induced ovulation or turnover of the largest follicle, induction of a new follicular wave, followed later by increased concentrations of estradiol-17beta and progesterone. After PGF(2alpha), greater GnRH-induced release of LH occurred in GnRH+NORG cows before ovulation, and pregnancy rates were greater after a fixed-time AI.
Bacterial lipopolysaccharide endotoxins (LPS) elicit inflammatory responses reflective of acute bacterial infection. We determine if feeding ewes high (15.5 %) or low (8.5 %) CP diets for 10 d ...altered inflammatory responses to an i.v. bolus of 0 (control), 0.75 (
L75
), or 1.50 (
L150
) μg LPS/kg BW in a 2 × 3 factorial (n = 5/treatment). Rectal temperatures, heart and respiratory rates, blood leukocyte concentrations, and serum cortisol, insulin, and glucose concentrations were measured for 24 h after an LPS bolus (bolus = 0 h). In general, rectal temperatures were greater (
P
≤ 0.05) in control ewes fed high CP, but LPS increased (
P
≤ 0.05) rectal temperature in a dose-dependent manner at most times between 2 and 24 h after bolus. Peak rectal temperature in L75 and L150 occurred 4 h after bolus. A monophasic, dose-independent rise (
P
≤ 0.023) in serum cortisol occurred from 0.5 to 24 h after bolus, with peak cortisol at 4 h. Serum insulin was increased (
P
≤ 0.016) by LPS in a dose-dependent manner from 4 to 24 h after bolus. Insulin did not differ between control ewes fed high and low CP diets but was greater (
P
< 0.001) in L75 ewes fed low compared with high CP and in L150 ewes fed high compared with low CP. Elevated insulin was not preceded by elevated serum glucose. Total white blood cell concentrations were not affected (
P
≥ 0.135) by LPS, but neutrophil and monocyte fractions of white blood cells were increased (
P
≤ 0.047) by LPS at 12 and 24 h and at 24 h after bolus, respectively, and lymphocyte fraction was increased (
P
= 0.037) at 2 h and decreased (
P
≤ 0.006) at 12 and 24 h after bolus. Red blood cell and hemoglobin concentrations and hematocrit (%) were elevated (
P
≤ 0.022) by LPS at 2 and 4 h after bolus. Rectal temperatures and serum glucose were greater (
P
≤ 0.033) in ewes fed a high CP diet before LPS injection, but these effects were lost at and within 2.5 h of bolus, respectively. Feeding high CP diets for 10 d did not reduce inflammation in ewes during the first 24 h after LPS exposure but may benefit livestock by preventing acute insulin resistance when endotoxin exposure is mild.
Abstract
Increased salivary cortisol in cattle may be detrimental to rumen bacterial diversity. Effects of transportation and diet before transportation on plasma and salivary cortisol and on rumen ...conditions of 20 ruminal-cannulated heifers (346 ± 16 kg BW) were evaluated. Heifers were fed ad libitum 40% Sorghum Sudan grass hay and 60% commercial pellet (64% TDN, 12.4% CP, DM basis) for 13 d before study initiation. Heifers were randomly assigned to a 2 × 2 factorial arrangement of 8-h transportation (TR) vs. no transportation (NT) and 100% Sorghum Sudan grass hay (HAY) vs. 30% hay and 70% pellets (H+P) fed ad libitum for 3 d before transportation. All groups were fasted during the 8-h transit period. Upon feedlot arrival at 8 h, cattle were fasted an additional 4 h. At 12 h, cattle were fed 30% wheat hay and 70% commercial feed (69% TDN, 16.6% CP, DM basis). Blood and ruminal fluid were sampled at 0, 8, 12, 24, 28 and 72 h. No diet × transport interactions were observed for any variable. Plasma cortisol was decreased for HAY vs. H+P heifers at 72 h (P < 0.05, diet × hour). Rumen pH and total volatile fatty acid concentrations did not differ between groups. Molar percentages of acetate increased, molar percentages of propionate decreased, and acetate-to-propionate ratios increased at 0 and 12 h for HAY compared to H+P (P < 0.05, diet × hour). At 0 h, molar percentages of butyrate were less for HAY vs. H+P (P < 0.05, diet × hour). Bacterial phyla richness was decreased for NT/HAY compared to NT/H+P and was increased for TR/HAY compared to TR/H+P heifers (P < 0.05, diet × transport). Proteobacteria relative abundances were less at 0 h for heifers fed HAY vs H+P (P < 0.05, diet × hour). Genera evenness was increased at 8 h for TR compared to NT cattle (P < 0.05, transport × hour). Genera Shannon-wiener indices were greater at 0 and 8 h for cattle consuming HAY compared to H+P (P < 0.05, diet × hour). Genera richness was increased at 0 h for cattle fed HAY compared to H+P (P < 0.05, diet × hour). Prevotella relative abundances were less for cattle fed HAY compared to H+P at 0 and 8 h (P < 0.05, diet × hour). In summary, due to negligible response to transportation, salivary cortisol effect on bacteria population and diversity were presumably minimal.
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