Intramuscular Fat Deposition in Steers Is Accelerated at a Set Body Weight

Seventy-two Angus crossbred steers (average initial BW, 351 ± 5.5 kg) were used to ascertain the breakpoint in BW above which intramuscular fat deposition was accelerated. Steers were randomly assigned to one of three treatments in an unbalanced study; treatment groups represented a BW at which steers would enter the feedlot (363, 408, or 454 kg). Until entering the feedlot, steers were grazed on pasture and supplemented to achieve 0.8 kg gain/d. Intramuscular fat deposition, measured ultrasonically, and live BW were acquired on d 0 and at 28-d intervals thereafter on each animal until harvest. In the feedlot, steers were fed a 13.4% CP concentrate diet until they reached a final BW of approximately 567 kg. After slaughter, carcass data were collected. No differences (P < 0.05) in ADG on pasture (0.85 ± 0.14 kg) or in the feedlot (1.70 ± 0.07 kg) occurred among treatments. There was good agreement between predicted and measured carcass quality grade (QG) (5.5 and 5.2, respectively). Based on broken-line analysis, deposition of intramuscular fat began to increase at approximately 378 kg regardless of BW at entry into the feedlot. The breakpoint BW for increased intramuscular fat accretion rate was calculated as 64% of mature BW of these steers.     

Effect of using Acacia mearnsii tannin extract as a feed additive on nutritional variables and productive performance in dairy cows grazing a temperate pasture

This study was carried out to evaluate the impact of including Acacia mearnsii tannin extract (TA) as a feed additive on nutrition and productive performance of dairy cows grazing a high‐quality temperate pasture and receiving supplementation with a concentrate feedstuff. Fourteen multiparous Holstein cows were assigned to either of the following treatments: concentrate without or with 20 g TA/kg dry matter (DM). Concentrate intake accounted for 32% of the total DM intake. Tannin addition increased the herbage DM intake by 22% (p < .05). There was no effect of TA inclusion on milk yield, milk composition, milk nitrogen (N) excretion, milk and plasma urea‐N concentration, urinary excretion of total N, urea‐N, and purine derivatives. However, TA inclusion increased the N intake and retention, total N excretion in manure, fecal N to urine N ratio, and decreased the dietary N efficiency for milk production and the percentage of ingested N excreted in urine (p < .05). In conclusion, supplementing dairy cows grazing a high‐quality temperate pasture with a concentrate containing 20 g TA/kg DM showed the potential of decreasing the proportion of ingested N excreted in urine without affecting the productive performance.     

Lasalocid Supplementation of Dairy Cow Diets in Early Lactation

A 36-cow study was conducted to evaluate the effects of lasalocid on feed intake, milk production and composition, and various blood metabolites in early lactation. Multiparous Holstein cows were assigned at parturition to a total mixed diet containing 33% corn silage, 17% chopped alfalfa hay, and 50% concentrate mix on a DM basis for 10 wk. An additional 2.3 kg of alfalfa hay was fed during the first 7 d in milk (DIM). Diets were supplemented with 0, 180, or 360 mg/d of lasalocid in a completely randomized design. Covariant-adjusted mean (the covariate was mature equivalent milk production from the previous lactation) DMI; milk and fat-corrected milk (FCM) production; percentages of milk fat, protein, and solids-not-fat; milk somatic cell count; BW; body condition score; and concentrations of glucose, β-hydroxybutyrate, and non-esterified fatty acid (NEFA) in blood were unaffected by supplementation with lasalocid. A dose of 360 mg/d of lasalocid may not be enough to significantly affect high-producing cows consuming >20 kg/d of DM.     

Comparison of Swine Diets Containing a Food Waste Product Made with Wheat Middlings and Corn or a Corn/Soybean Diet,

Although pigs will readily consume wet food waste (FW), the high moisture content contributes to spoilage and feeding management problems. The use of a dry, processed FW product was compared with a traditional corn and soybean (CS) diet using growing swine in two performance trials and one digestibility trial. The FW diet contained approximately 20% processed FW (DM basis). In Trial 1, 24 gilts (76.4 kg) housed in eight replicated pens (four pens per treatment) were fed in a 6-wk trial. Intake, BW gain, feed efficiency, and carcass characteristics were compared. Feed intake and BW gain averaged 3.4 and 3.6 kg of DM/d and 0.87 and 0.85 kg/d for gilts fed traditional and FW diets, respectively. There were no differences in these or any other measurements (P>0.05). In Trial 2, 12 barrows (84.3 kg) housed in four replicated pens (two pens per treatment) were fed in a 6-wk trial. Intake, BW gain, feed efficiency, and carcass characteristics were compared. Feed intake and BW gain averaged 3.1 and 3.3 kg of DM/d and 0.62 and 0.71 kg/d for barrows fed traditional and FW diets, respectively. Four growing gilts (68.2 kg) were used to compare digestibility in a crossover design. There were no differences (P>0.10) for DM, CP, ADF, or NDF digestibility when feed intake averaged 1.9 kg of DM/d for both FW and CS diets. The use of up to 20% processed FW may be suitable in commercial swine diets.     

Effects of Pre-Weaning Vitamin E,Selenium, and Copper Supplementation on the Performance,Acute Phase Protein Concentration,and Immune Function of Stressed Beef Calves

Two experiments were conducted to determine the effects of pre-weaning vitamin E, Se, and Cu supplementation on performance and immune response in stressed calves. In Exp. 1, 71 Hereford x Angus calves were individually creep fed: 1) control supplement (CON), 2) control plus 500 IU vitamin E + 0.3 mg Se/kg DM (E), 3) control plus 10 mg Cu/kg DM (CU), or 4) a combination of E and CU treatments (ECU). In Exp. 2, 80 Hereford (Angus calves were individually creep fed: 1) control supplement (CON), 2) control plus 0.3 mg Se/kg DM (SE), 3) control plus 500 IU vitamin E + 0.3 mg Se/kg DM (LOWE), 4) control plus 1000 IU vitamin E + 0.3 mg Se/kg DM (MEDE), or 5) control plus 1500 IU vitamin E + 0.3 mg Se/kg DM (HIE). Treatments continued for 49 (Exp. 1) or 53 d (Exp. 2) prior to weaning. At weaning all calves were transported to feedlot facilities. In Exp. 1, vitamin E tended (P<0.09) to improve post-weaning ADG and reduce (P<0.06) plasma haptoglobin (Hp), but had no effect on plasma α-tocopherol. Dietary Cu tended to increase (P<0.01) liver Cu stores, and antibody titers to bovine viral diarrhea (BVD) were greater (P<0.04) at weaning in CU and E calves. In Exp. 2, vitamin E tended to increase serum α-tocopherol (P<0.06) and cortisol (P<0.08). Vitamin E and Se supplementation may improve post-weaning performance and decrease plasma Hp concentrations in stressed calves.     

Effect of herbage allowance and concentrate supplementation on dry matter intake, milk production and energy balance of early lactating dairy cows

The objective of this study was to investigate the effect of daily herbage allowance and concentrate supplementation level offered at approximately 40 and 80 days in milk (DIM) and the carryover effects at 120 DIM on the production performance of spring calving dairy cows. Sixty-six (30 primiparous and 36 multiparous) Holstein–Friesian dairy cows (mean calving date — 7 Feb ± 9.9 days) were randomly assigned to a 6 treatment (n = 11) grazing study. The experiment was a randomised block design with a 3 × 2 factorial arrangement of treatments (3 daily herbage allowances (DHA's; approximately 13, 16 and 19 kg DM/cow/day; > 4 cm) and 2 concentrate allowances (0 and 4 kg DM/day). Treatments were imposed from 21 February to 8 May. Following this period (subsequent 4-weeks) animals were offered a daily herbage allowance of 20 kg DM/cow/day and no concentrate. Milk production, total dry matter intake (TDMI), energy balance (EB) and blood metabolites were measured on three occasions — at approximately 40, 80 and 120 days in milk, R1, R2 and the carryover period, respectively. Cows offered a low DHA had a lower post-grazing sward height but increased sward utilisation (> 4 cm) during R1 and R2, there was no difference during the carryover period. Concentrate supplementation increased post-grazing sward height by 11% during R2 but had no effect during R1 and the carryover period. Daily herbage allowance had no effect on milk yield or composition during R1 however a low DHA tended to reduce milk yield in R2. Concentrate supplementation increased milk and solids corrected milk (SCM) yield by 4.1 and 2.8 kg/cow/day, respectively during R1 and also increased R2 milk production performance, this effect extended into the carryover period. Offering a low DHA restricted grass dry matter intake (DMI) during R1 and R2 yet concentrate supplementation significantly increased total DMI (2.3 (R1) and 3.0 (R2) kg DM/cow). Animals offered a low DHA had a significantly lower bodyweight (BW) than those offered a medium or high DHA during P1 and P2. Concentrate supplementation increased BW during P1 and P2 (+ 9 and + 14 kg/cow, respectively). There was no effect of treatment on BW during P3. There was no effect of DHA on EB in R1; during R2 animals offered a low DHA had the lowest EB. Concentrate significantly increased EB in R1 and R2 and increased plasma glucose concentration while it decreased plasma NEFA and BHB concentrations. The results of this study indicate that animals should be offered a low DHA up to 80 DIM after which DHA should be increased however animals should also be supplemented with concentrate during the early post-partum period.     

Effects of inclusion of whole-crop pea silages differing in their tannin content on the performance of dairy cows fed high or low protein concentrates

The effect of including high or low tannin forage peas as an alternative to soyabean meal on performance and N efficiency was investigated using 18 dairy cows in two Latin square design studies. Two varieties of forage pea; Racer (coloured flowers; high tannin) and Croma (white flowers; low tannin), were ensiled 12 weeks post sowing. The in situ degradability characteristics of the pea silages were determined using 4 cannulated sheep. The low tannin forage had a higher soluble N (a) fraction and a greater extent of degradation (a + b), resulting in a greater amount of N being predicted to be released in the rumen than the high tannin forage. In experiment 1, cows were fed one of three treatments in each of 3 periods of 28 d duration in a Latin square design; grass silage/whole-crop wheat (0.50:0.50, DM basis) and 8 kg/d of a high protein concentrate (GWH); grass silage/whole-crop wheat/high tannin forage pea silage (0.25:0.25:0.50 respectively, DM basis) and 8 kg/d of a high protein concentrate (HTH) or 8 kg/d of a low protein supplement (HTL). The inclusion of forage peas increased (P < 0.05) DM intake by 1.2 kg DM/d, but there was no effect of dietary treatment on milk yield (average of 23.0 kg/d), composition or live weight change. The efficiency of use of dietary N (N output in milk/N intake) was highest (P < 0.001) in cows when fed GWH (0.289) and lowest in HTH (0.234). In experiment 2, cows were fed one of three treatments in each of 3 periods of 28 d duration in a Latin square design; grass silage/whole-crop wheat (0.50:0.50, DM basis) and 8 kg/d of a high protein concentrate (GWH); grass silage/whole-crop wheat/low tannin forage pea silage (0.25:0.25:0.5 respectively, DM basis) and 8 kg/d of a high protein concentrate (LTH) or 8 kg/d of a low protein concentrate (LTL). Compared with GWH, the inclusion of forage peas increased (P < 0.05) DM intake by 2.0 kg/d, but there was no effect of dietary treatment on milk yield (average of 24.5 kg/d). Milk fat content was highest (P < 0.05) in cows when fed LTL (45.7 g/kg) and lowest in LTH (41.9 g/kg), but there was no effect (P > 0.05) of treatment on daily fat yield or any other milk component. The efficiency of dietary N use was highest (P < 0.001) in cows when fed GWH (0.300) and lowest in LTH (0.234). It is concluded that either high or low tannin forage pea silages can replace approximately 1.1 kg/d of soyabean meal in the diet of mid-late lactation dairy cows without affecting animal performance, but N efficiency for milk production is decreased.     

Performance of Steers Supplemented with Zinc During Grazing and Receiving at the Feedlot

A study was conducted to compare the effects of three supplemental zinc sources on beef steers grazing winter annual pasture and during receiving in a feedlot. In southern Arkansas, 84 steers were weighed (BW = 216 ± 1.5 kg), bled via jugular puncture, and randomly assigned to 12 bermudagrass pastures (0.81 ha each) that had been overseeded with wheat, rye, and annual ryegrass (7 steers per pasture; 116 d of grazing) on January 15; the steers were allowed to graze until May 11. Steers were fed 0.45 kg daily of corn-based supplement containing 103 mg zinc from ZnSO₄, zinc amino acid complex (ZnAA), or zinc polysaccharide (ZnPOL) during the entire grazing period. On May 12, steers were shipped to a research feedlot (14 h; 1,016 km; 6.9% BW shrink) in northeast New Mexico. In the feedlot, the same groups of steers were fed a receiving diet (steam-flaked milo) that contained the same zinc sources as fed during the grazing period. Dietary concentrate was increased from 75 to 85% of dietary DM weekly. Data were analyzed as a completely random design; least squares means were separated using contrast. Steer BW on d 28 and 84 of the grazing period were greater (P<0.05) for cattle fed ZnAA and ZnPOL than for steers fed ZnSO₄; however, ADG over the 116 d of grazing and ending BW did not differ (P>0.28) among zinc sources. In the feedlot, steer BW, ADG, and feed efficiency did not differ (P>0.05) among zinc sources. Serum zinc concentrations did not differ (P>0.05) among zinc sources at any point in time. We conclude that early in the grazing period, ZnAA and ZnPOL improved steer BW compared with ZnSO₄; however, no differences were noted among zinc sources later in the grazing period or during receiving in the feedlot.     

Growth Performance by Stocker Steers Fed Magnesium-Mica During a Grazing and Feedlot Period

Two experiments were conducted to determine the effects of Mg-mica supplementation on grazing and feedlot performance of stocker steers. In Exp. 1, eight groups of six steers were fed a basal diet of 80% ground grain sorghum, 15% corn silage, and 5% control protein supplement (DM basis) or a supplement containing Mg-mica (9% of supplement; 4.5 mg/kg diet DM) for 141 d. Marbling scores tended (P<0.10) to be greater, and the percentage of carcasses grading USDA Choice or higher was greater (P<0.05), from steers fed Mg-mica than from those fed the control supplement. In Exp. 2, eight groups of nine head each were offered either a control grain sorghum-based supplement or one containing 34 g/d of Mg-mica (2.7 g Mg) while grazing smooth bromegrass pastures for 112 d. Pasture groups were then placed in feedlot pens for 120 d and fed a basal diet similar to that described above. Two groups fed each pasture supplement received a control supplement, and two received a supplement containing Mg-mica (10% of supplement; 5 mg/kg diet DM). Steers fed Mg-mica during the pasture phase tended to have heavier (P=0.11) hot carcass weights, higher (P<0.05) dressing percentages, numerically (P>0.10) higher marbling scores, and a higher percentage of carcasses grading USDA Choice than steers fed the control supplement during the pasture phase. Therefore, adding Mg-mica to pasture supplements or feedlot diets appears to have no impact on grazing or feedlot performance, but may improve carcass quality.     

Influence of Both Endophyte Infestation in Fescue Pastures and Calf Genotype on Subsequent Feedlot Performance of Steers

Three experiments were conducted to determine the influence of both the concentration of endophytic fungus infestation in tall fescue pastures and calf genotype on the subsequent health and performance of steers in the feedlot. In Exp. 1 and 2, Angus steers grazed fescue pastures in Georgia containing low, moderate, or high endophyte infestations for 182 d (Exp. 1) or 78 d (Exp. 2) with 12 steers per treatment. Steers were transported 1,600 km to Texas in October (Exp. 1) and July (Exp. 2), were fed a 93% concentrate diet during the finishing period, and were harvested at an estimated backfat thickness of 12 mm. In both trials, DMI over the entire feeding period and carcass characteristics were not affected (P>0.05) by endophyte infestation. In both trials, pasture ADG decreased, and feedlot ADG and gain to feed ratio increased as the previous pasture endophyte infestation increased (P<0.05). Serum cholesterol concentrations tended (P<0.10) to decrease with increasing endophyte infestation during the first 14 d in the feedlot. In Exp. 3, Angus and Brahman × British crossbred steers grazed fescue pastures in Georgia containing low, moderate, or high endophyte in each of 2 yr. Six steers of each breed group were on each treatment each year. Steers were transported to Texas in late August of each year, were fed a 93% concentrate finishing diet, and were harvested at an estimated individual backfat thickness of 12 mm. As endophyte infestation increased, serum urea N concentrations and gain to feed ratios increased (P<0.05), whereas pasture ADG, initial BW, transit shrink, serum cholesterol concentrations, final BW, and carcass weights decreased (P<0.05) in Angus steers, but not in Brahman-cross steers. In these studies, the adverse effects of high endophyte infestations in fescue pastures appeared to carry over to the feedlot for ca. 14 d. However, steers from highly infested pastures can compensate for poor pasture performance with improved performance in the feedlot when no adverse health effects occur. Any impact of the endophyte seems to be similar in Brahman-cross and Angus steers.     

Growth Performance and Serum Mineral Concentrations of Stocker Calves Grazing Wheat Pastures and Fed Different Sources of Magnesium,

Magnesium supplementation has been shown to benefit feedlot cattle and is typically added at high concentrations to mineral supplements for calves grazing wheat pasture. Two experiments were conducted to determine the effects of Mg-mica supplementation on performance and serum mineral concentrations of stocker calves grazing wheat pasture. Supplemental Mg was provided at 6.1 g/d of supplemental Mg/ animal, Monday through Friday. In Exp. 1, 36 mixed-breed stocker calves (243 ± 3.9 kg BW) were stratified by BW and gender and allocated randomly to one of nine groups of four animals for a 112-d grazing study. Weight gain, shrink percentage, and serum Mg, Ca, K, Cu, and Zn concentrations did not differ (P>0.10) among calves fed either weathered Mg-mica (WMM), unweathered Mg-mica (UMM), or MgO. All serum mineral concentrations were within normal physiological ranges. In Exp. 2, 64 mixed-breed stocker steers (275 ± 1.7 kg BW) were stratified by BW and allocated randomly to one of 16 groups of four animals. Weight gain during a 50-d grazing study and subsequent feedlot period did not differ (P>0.10) among calves fed either no added Mg source or WMM, UMM, or MgO. Serum Cu was higher (P<0.05), and serum Mg was lower (P<0.05), from steers fed MgO, but all serum mineral concentrations were within normal physiological ranges. Although Mg-mica is relatively high in Fe (4%), using it as a supplemental Mg source appeared to have no negative impact on growth performance or serum mineral concentrations of calves grazing wheat pasture.     

Effects of a Brown‐midrib corn hybrid on nutrient digestibility in wethers and on dry matter intake,performance, rumen and blood variables in dairy cows

The aim of the present trials was to determine the effect of an experimental Brown‐midrib (Bm) corn hybrid in relation to a commercial corn hybrid (Con) on digestibility in wethers and on dry matter intake (DMI), milk yield and milk composition in dairy cows. Digestibility of crude fibre (CF), neutral detergent fibre (NDFom) and acid detergent fibre (ADFom) were higher for Bm (CF Con: 57.8%; Bm: 67.2%; NDFom Con: 56.8%; Bm: 64.8%; ADFom Con: 52.0%; Bm: 63.9%), but concentration of net energy for lactation did not differ (Con: 6.4 MJ/kg DM; Bm: 6.3 MJ/kg DM). A total of 64 lactating German Holstein cows were assigned to one of the two dietary treatments Con or Bm according to milk yield, lactation number, days in milk and live weight. In Trial 1, cows were fed a total mixed ration consisting of 50% corn silage (Con or Bm) and 50% concentrate on dry matter (DM) basis. In Trial 2, the same animals were fed the respective silage for ad libitum intake and 5.3 kg of concentrate DM per animal per day. In Trial 1, DMI and milk‐fat content were decreased significantly for the Bm‐treatment (DMI Con: 22.5 kg/day; Bm: 21.5 kg/day; milk fat Con: 3.8%; Bm: 3.3%). In Trial 2, milk yield and fat‐corrected milk (FCM) were increased significantly, whereas milk‐fat% was decreased significantly (milk yield Con: 25.8 kg/day; Bm: 29.4 kg/day; FCM Con: 27.2 kg/day; Bm: 29.6 kg/day; fat Con: 4.4%; Bm: 4.0%). Diets did not influence ruminal pH or temperature. Diets, furthermore, did not influence rumination in either trial. Additional research on digestibility and rumen fermentation should, however, be carried out using dairy cows at respective intake levels as trials with wethers cannot be transferred to high‐yielding ad libitum fed cows.     

Phosphorus Intake and Excretion on South Carolina Dairy Farms

The objective of this study was to survey dairy farmers to determine P levels in feed and manure. Feed and manure samples were collected from 19 Holstein, six Jersey, and two Guernsey farms in South Carolina. Samples from the Jersey and Guernsey herds were pooled. Samples were dried and analyzed for N and P. Amounts of all feeds were recorded; then, nutrient intake was determined. Dairy Herd Improvement records were used to determine the milk yield and fat content and, subsequently, the P requirement. Nineteen of 27 herds (70%) were fed more P than required according to nutrient requirements established by the NRC. The average P intake was 94.9 g (0.48% of diet DM) compared with the average requirement of 78.3 g (0.41% of diet DM). There were correlations between dietary and fecal P (R² = 0.46) and between CP and P intake (R² = 0.62). There was not a significant correlation between excess P intake and milk yield. In summary, many dairy producers overfeed P. Feeding dietary P at recommended levels will optimize milk yield and reduce P excretion on dairy farms.     

Concentrate supplementation responses of the pasture-fed dairy cow

The aim of this study was to investigate the effects of increasing amounts of cereal-based concentrate on milk production. The study consisted of a series of three separate experiments in which cows were grazed in intensive rotation on timothy-meadow fescue pasture. In Experiment 1, 28 multiparous Holstein–Friesian cows received 0, 3, 6 and 9 kg concentrate in a cross-over designed trial with a fixed daily herbage allowance of 21 kg DM/cow. The energy-corrected milk yield increased linearly 0.84 kg/kg DM (P < 0.001), up to the 9 kg concentrate level. The milk fat (P < 0.001) and urea (P < 0.001) content decreased linearly (0.41 g/kg DM and 0.15 mmol/kg DM, respectively). The milk protein content tended (P = 0.08) to increase 0.10 g/kg DM with increasing supplementation.

In Experiment 2, 17 primiparous cows and 28 multiparous cows were used in a randomized-block designed trial with 3, 6 and 9 kg concentrate supplementation and a fixed 25 kg DM herbage allowance. The energy corrected milk yield increased linearly (P < 0.01) 0.67 kg/kg DM, whereas the milk urea content decreased linearly (P < 0.001) 0.27 mmol/kg DM. The milk protein content increased and the fat content decreased, but these differences were not significant.

In Experiment 3, a cross-over design was used to assess the response to concentrate supplementation of 24 multiparous cows (treatments: 6, 9 and 12 kg; fixed herbage allowance 25 kg DM) and 12 primiparous cows (treatments: 4, 7 and 10 kg; herbage allowance > 25 kg DM). The energy-corrected milk yield of the multiparous cows varied quadratically (P_quad < 0.001; 30.0, 32.5 and 32.2 kg for 6, 9 and 12 kg supplementation, respectively). Supplementation linearly decreased the urea (P < 0.001) 0.13 mmol/kg DM and fat (P < 0.001) 0.46 g/kg DM contents. The milk fat content also varied quadratically, showing the lowest content with the 12 kg level (P_quad < 0.05; 37.3, 37.3 and 34.9 g/kg for 6, 9 and 12 kg supplementation, respectively). The energy-corrected milk yield of the primiparous cows increased linearly (P < 0.001) 0.54 kg/kg DM up to 10 kg supplementation, whereas the milk urea (P < 0.001) and fat contents decreased linearly (P < 0.01) by 0.19 mmol/kg DM and 0.61 g/kg DM, respectively.

The results showed that the milk response remained linear up to the 9 kg supplementation level, but the highest level of supplementation resulted in only a marginal increase in milk yield. There was no interaction between season and milk or milk protein yield, which indicates that it is possible to maintain stable grazing conditions during the main grazing season in Nordic latitudes. The results support to some extent the hypothesis that the marginal milk response to supplementation increases with increasing milk production.     

Influence of Betaine on Pasture,Finishing, and Carcass Performance in Steers

Two experiments were conducted to investigate the effects of supplemental betaine on steer performance, fat deposition, and carcass characteristics. In Exp. 1 (grazing phase), 80 steers (317 kg) were fed either 1.0 kg of a control supplement (30% CP) or 1.0 kg of the control supplement plus 20 g of betaine per head per day. Betaine supplementation had no effect on overall gain or fat deposition (P>0.10) but increased ADG (P<0.10) during d 46 to 90 (0.64 vs 0.72 kg; control vs betaine, respectively). The pasture groups remained intact and were moved to the feedlot for 141 d and fed a control diet or the control diet plus 20 g of betaine per head per day. Betaine had no overall effect on finishing gain (P>0.10); however, this response was variable by period. Betaine increased final fat thickness and fat thickness change (P<0.10), but did not affect marbling or longissimus area (P>0.10). Supplemental betaine on pasture increased feed intake, final BW, and hot carcass weight (P<0.05) and increased final fat thickness and fat thickness change (P<0.10) during the finishing phase. In Exp. 2, supplemental betaine (40 g/d) was fed to steers (averaging 584 kg) in 11 replications during the last week before harvest. The overall weighted average increase in dressing percentage when betaine was fed was +0.34% (P<0.05). There was no effect (P>0.10) on fat thickness or marbling. Season of year did not affect response.     

Supplementing Guinea grass with fresh sweet potato foliage for milk production by Bunaji and N'Dama cows in early lactation

Forage from three sweet potato cultivars (A = TIS-87/0087; B = TIS-8164; C = TIS-2532.OP.1.13 at 30% daily dry matter intake), dried brewers' grains (DBG) and cottonseed meal (CSM) each at 2.5 kg were supplemented to Guinea grass (GG) to form four diets: Diet A = GG + TIS-87/0087; Diet B = GG + TIS-8164; Diet C = GG + TIS-2532.OP.1.13, and Diet D = GG + DBG + CSM (as control). Treatments were assigned as 4 × 4 Latin squares design over 60 days (10-day adaptation and 5-day sampling) using Bunaji and N'Dama cows in early lactation. The 48-h rumen dry matter (DM) degradation ranged (P < 0.01) from 407 g kg^? 1 DM for GG to 791 g kg^? 1 DM for sweet potato cultivar TIS-87/0087. Bunaji dry matter intake varied (P < 0.05) between 7.1 kg day^? 1 in Diet B and 8.9 kg day^? 1 in Diet D, but was similar (P > 0.05) among diets for the N'Dama cows. The metabolisable energy (ME) intakes were higher for Diet D although, it recorded the least efficiency of ME utilization for milk production. Milk yields were significantly (P < 0.01) higher in the Bunaji than the N'Dama cows, which is typical of their true breed differences. Total solids, ash, protein, fat, and sugar contents of the milk were similar among diets for both cow breeds, except Bunaji ash contents that ranged (P < 0.05) from 0.77 g 100 g^? 1 for Diet B to 0.83 g 100 g^? 1 for Diet D. The results suggest that sweet potato forage could be utilized as whole or partial replacement for DBG and CSM to save cost under smallholder farming systems.     

Effects of Organic Chromium on Protein Synthesis and Glucose Uptake in Ruminants

In vitro glucose uptake and protein synthesis were measured using serum from feedlot steers fed diets supplemented with organic Cr (OCr); glucose clearance was studied using sheep as a model. Treatments investigated for glucose uptake and protein synthesis were 1) control (0 ppm supplemental Cr), 2) 0.2 ppm supplemental OCr from high Cr yeast, and 3) 0.4 ppm supplemental OCr from high Cr yeast that contained 2,000 ppm Cr (2 mg Cr/g Saccharomyces cerevisiae yeast) added to a 90% concentrate feedlot diet. The form of OCr supplied by high Cr yeast is presumably a glucose tolerance factor (GTF), which potentiates the action of insulin, and consists of Cr³⁺ centrally bound to or associated with cysteine, glutamate, glycine, and nicotinic acid residues. Serum harvested from steers fed 0.2- and 0.4-ppm OCr diets increased (P<0.05) protein synthesis in primary bovine muscle cultures. Glucose uptake rate by muscle cell cultures was increased (P<0.09) by serum from OCr-supplemented steers. Treatments investigated for glucose clearance by lambs were 1) control (0 ppm supplemental Cr), 2) 0.2 ppm, 3) 0.4 ppm, and 4) 0.8 ppm supplemental OCr from high Cr yeast added to a 85% concentrate finishing diet. Glucose clearance in lambs was improved (P<0.05) by addition of 0.2 and 0.8 ppm OCr to the diet. These results are interpreted to suggest that increased carcass muscling in ruminants fed OCr-supplemented diets is a result of improvements in amino acid uptake and glucose metabolism within muscle cells.     

Nitrogen efficiency of dairy cows as affected by diet and milk yield

The aim of this study, which was part of the EU-financed project Life Ammonia, was to evaluate the effects of dietary components and milk production on nitrogen efficiency of dairy cows. The study included examining the effects of decreased crude protein (CP) concentration in a grass-clover silage based diet and results of mixing whole-crop barley silage (WCBS) with grass-clover silage in the diet, on feed intake, milk production and nitrogen efficiency. Rations were formulated and milk production data were registered individually each month for 42 cows of the Swedish Red Cattle breed during four indoor periods from 1999 to 2003. The range in nitrogen efficiency by the cows, 11 to 398 days in milk, was 18 to 40%, when fed a diet containing 135 to 184 g CP/kg DM, 44 to 56% of NDF as rumen degradable fibre (RDF) and milking 13 to 57 kg of ECM daily. The average CP concentration of the diet, containing mainly grass-clover silage and concentrate, was decreased from 168 g/kg DM (170 g in early lactation) in the control treatment period to 160 g/kg DM (163 g in early lactation) during the following treatment period. The CP concentration was 170 g/kg DM (171 g in early lactation) during the third treatment period, when the grass-clover silage was fed in a mixture with WCBS. Using the whole data set (n = 284 for primiparous, n = 440 for multiparous cows based on measurements each month) resulted in models, in which total DM intake, ECM yield, dietary CP concentration and RDF were the most important factors affecting nitrogen utilisation of primiparous and multiparous cows. Increases in both average DM intake and milk yield by multiparous cows and no changes in average intake and milk yield by primiparous cows fed the low CP diet or the normal CP diet containing WCBS, compared to cows fed the normal CP diet, resulted in similar nitrogen efficiencies among the treatments. Hence, dietary CP concentrations of 160 to 170 g/kg DM can be used for cows in early lactation in commercial herds to improve nitrogen utilisation without causing a simultaneous decrease in milk yield.     

The Immune Response and Performance of Calves Supplemented with Zinc from an Organic and an Inorganic Source

Two experiments were conducted to determine the effects of supplemental zinc (Zn) from an organic and an inorganic source on growth performance, serum Zn concentrations, and immune response of beef calves. Treatments consisted of: i) control (no supplemental Zn), ii) Zn sulfate, or iii) Zn–amino acid complex. Zinc sources were supplemented to provide 360 mg of Zn/d. Experiment 1 was a 28-d study using 84 steers (240 ± 1.5 kg) fed bermudagrass hay (21 mg Zn/kg DM) with 1.8 kg/d of the appropriate corn-based supplement. In Exp. 2, 75 heifers (176 ± 2.5 kg) were fed bermudagrass hay (38 mg Zn/kg DM) and the supplements for 140 d. In Exp. 1, ADG was greater (P<0.05) from d 15 to 28 in calves fed supplemental Zn-amino acid compared with those fed Zn sulfate, but ADG did not differ (P>0.10) among treatments for the entire 28-d study. In Exp. 2, there was no effect (P>0.10) on ADG as a result of Zn supplementation. In Exp. 2, Zn-supplemented heifers had a greater response (P=0.06) to phytohemagglutinin 24 h after an intradermal injection. In Exp. 2, calves supplemented with Zn–amino acid complex had a greater antibody response to a second vaccination for bovine respiratory syncytial virus than did control or Zn sulfate-supplemented calves (treatment by day interaction, P=0.06). There was not a consistent benefit of supplemental Zn on growth of calves, but there was a positive impact of supplemental Zn on some immune-response measurements.     

Enzymatically Digested Animal Protein as a Source of Protein for Weanling Pigs

Three experiments were conducted to evaluate the use of an enzymatically digested animal protein (EDAP) as a source of protein for weanling pigs. In each experiment, treatments were replicated with four (Experiments 1 and 2) or seven (Experiment 3) pens of three to five pigs each. Each experiment lasted 3 to 4 wk for the combined Phase I (1.5% Lys in Experiments 1 and 2, 1.6% Lys in Experiment 3) and Phase II (1.3% Lys) periods. In Experiments 1 (6.7 kg; 23 d of age) and 2 (6.1 kg; 22 d of age), pigs were fed one of the following Phase I diets: 1) basal (B) diet containing corn, soybean meal (SBM), whey, fish meal, and blood cells (AP-301 G; American Protein Corporation, Ames, IA); 2) B + 4% spray-dried animal plasma (SDAP); or 3) B + 2% SDAP + 2% EDAP (SDAP + EDAP). In Phase II, the dietary groups from Phase I were divided into two subsequent groups. One group received a diet containing corn, SBM, whey, fish meal, and 2% blood cells, and the second group received the same diet with 2% EDAP, resulting in six treatments for Phase II and overall periods. In Experiment 1, ADG and ADFI were increased (P<0.10) during Phase I for pigs fed SDAP + EDAP, and ADFI was increased (P<0.10) in pigs fed SDAP. In Phase II, the EDAP addition did not affect (P>0.10) ADG, ADFI, or the ratio of gain to feed. Also, Phase I diets did not affect (P>0.10) growth performance during Phase II. Overall, ADG (P<0.10) and ADFI (P<0.04) were increased (P<0.10) in pigs fed SDAP + EDAP during Phase I. In Experiment 2, ADG and the ratio of gain to feed were increased (P<0.10) in pigs fed SDAP + EDAP during Phase I. During Phase II, ADFI was increased in pigs fed SDAP + EDAP or B + SDAP (P<0.01) relative to those fed B only (P<0.003) in Phase I. Also in Phase II, the ratio of gain to feed was increased in pigs fed SDAP + EDAP (P<0.03) relative to those fed B + SDAP. Overall, ADG and the ratio of gain to feed were not affected (P>0.10) by diet, but ADFI was increased (P<0.03) in pigs fed SDAP + EDAP relative to those fed B. In Experiment 3, all pigs (5.7 kg; 17 d of age) were fed a common Phase I diet containing SDAP + EDAP. In Phase II, ADG, ADFI, and the ratio of gain to feed were not affected (P>0.10) by the addition of 2% EDAP or 2% blood cells. In summary, pigs fed SDAP + EDAP perform equally well compared with those fed B + SDAP.