Undegraded intake protein supplementation: I. Effects on forage utilization and performance of periparturient beef cows fed low-quality hay

Hereford x Angus cows (n = 36; initial wt = 568+/-59 kg) were used to evaluate effects of undegradable intake protein (UIP) supplementation on forage utilization and performance of beef cows fed low-quality hay. Treatments were control (unsupplemented) or one of three protein supplements. Supplements were fed at 1.3 kg DM/d and included UIP at low, medium, or high levels (53, 223, or 412 g UIP/kg supplement DM, respectively). Supplements were formulated to be isocaloric (1.77 Mcal NEm/kg) and to contain equal amounts of degradable intake protein (DIP; 211 g DIP/kg supplement DM). Intake of forage was measured daily during six 7-d collection periods, which approximated mo 7, 8, and 9 of gestation and mo 1, 2, and 3 of lactation. Prairie hay (5.8% CP) was offered daily for ad libitum consumption. Cows were weighed and condition-scored on d 7 of each period. Supplemented cows had greater (P = .01) total organic matter intake (g/kg BW) compared with control animals during gestation. Forage organic matter intake (g/kg BW) was greater (P< or =.02) for control cows than for supplemented cows during lactation. Digestion of OM and NDF was lower (P<.10) for control than for supplemented cows. Body weight of supplemented cows was greater (P = .01) than that of control cows on four of six weigh dates. Supplemental UIP did not affect (P> .10) cow body weight or condition score. Body condition scores of supplemented cows were higher (P = .02) during mo 9 of gestation and during mo 3 of lactation compared with controls. Reproductive performance was similar (P>.10) among treatment groups, and there were few differences in calf performance. These data were interpreted to suggest that supplemental protein can increase total tract OM and NDF digestion by beef cows and increase body weight. Increasing the level of UIP in the supplement had little effect on forage utilization or animal performance.     

Whole soybean supplementation and cow age class: effects on intake, digestion, performance, and reproduction of beef cows

Two experiments were conducted to determine the effects of whole soybean supplementation on intake, digestion, and performance of beef cows of varying age. Treatments were arranged in a 2 x 3 factorial with 2 supplements and 3 age classes of cows (2-yr-old, 3-yr-old, and mature cows). Supplements (DM basis) included 1) 1.36 kg/d of whole raw soybeans, and 2) 1.56 kg/d of a soybean meal/hulls supplement. Supplements were formulated to provide similar amounts of protein and energy, but a greater fat content with the whole soybeans. Supplements were individually fed on Monday, Tuesday, Thursday, and Saturday mornings. During the treatment period, cows had free choice access to bermudagrass hay [Cynodon dactylon (L.) Pers.; 8.4% CP; 72% NDF; DM basis]. In Exp. 1, 166 spring-calving Angus and Angus x Hereford crossbred beef cows were individually fed supplements for an average of 80 d during mid to late gestation. During the first 50 d of supplementation, cows fed soybean meal/hulls gained more BW (10 kg; P < 0.001) and body condition (0.18 BCS units; P = 0.004) than cows fed whole soybeans. However, BW change (P = 0.87) and BCS change (P = 0.25) during the 296-d experiment were not different between supplements. Although calves from cows fed soybean meal/hulls were 2 kg heavier at birth, there was no difference in calf BW at weaning between supplements. Additionally, first service conception rate (68%; P = 0.24) and pregnancy rate (73%; P = 0.21) were not different between supplements. In Exp. 2, 24 cows from Exp. 1 were used to determine the effect of supplement composition on forage intake and digestion; cows remained on the same supplements, hay, and feeding schedule as Exp. 1. Crude fat digestibility was the only intake or digestibility measurement influenced by supplement composition; fat digestibility was higher for cows fed whole soybeans compared with cows fed the soybean meal/hulls supplement (58.1 vs. 48.8%). Hay intake and DMI averaged 1.63 and 1.92% of BW daily, respectively. Dry matter, NDF, and CP digestibility averaged 54.1, 55.1, and 63.2%, respectively. Compared with supplementation with soybean meal/ hulls, whole soybean supplementation during mid to late gestation resulted in reduced BW weight gain during supplementation, inconsistent effects on reproduction, no effect on calf weaning weight, and no effect on forage intake or digestion.     

Effects of interval-feeding whole sunflower seeds during mid to late gestation on performance of beef cows and their progeny

This experiment was conducted to determine the effects of interval feeding of whole sunflower seeds on the performance of beef cows and their progeny. During mid to late gestation, 144 multiparous, spring-calving beef cows (588 kg of initial BW; 5.6 initial BCS; 4 to 13 yr old) were individually fed 1 of 3 supplements 4 d/wk for a 76-d period. Supplements (DM basis) included: 1) 0.68 kg of soybean meal/feeding (NCON); 2) 3.01 kg of a soybean hull-based supplement/feeding (PCON); and 3) 1.66 kg of whole sunflower seeds high in linoleic acid/feeding (WSUN). Supplements were formulated to provide similar amounts of CP and ruminally degraded intake protein; PCON and WSUN were also formulated to be isocaloric. During the supplementation period, cows had free-choice access to bermudagrass (Cynodon dactylon) and tall-grass prairie hay. By the end of the 76-d supplementation period, cows fed PCON (P < 0.01) and NCON (P < 0.01) had gained more BW than cows fed WSUN (33, 23, and 10 kg, respectively). However, from the end of this supplementation period to the beginning of the breeding season 84 d later, cows supplemented with PCON had lost more (P < 0.01) BW than cows supplemented with WSUN (-123 kg vs. -111 kg). Cow BW change through weaning (-50 kg, P = 0.43) and final cow BW (536 kg, P = 0.70) at weaning were not different among supplement groups. Furthermore, cow BCS was similar among supplement treatment groups at the end of the supplementation period (5.3, P = 0.09), at the beginning of the breeding season (4.8, P = 0.38), and at weaning (4.7, P = 0.08). No difference among treatments was detected for calf birth weight (36 kg, P = 0.42), calf weaning weight (235 kg, P = 0.67), percentage of cows exhibiting luteal activity at the beginning of the breeding season (57%, P = 0.29), or pregnancy rate (88%, P = 0.44). However, first service conception rate was greater (P = 0.01) for cows fed PCON (79%) and tended (P = 0.07) to be greater for cows fed WSUN (74%) than for cows fed NCON (53%). After weaning, all steer calves were placed in a feedlot and fed a high-concentrate finishing diet for an average of 188 d. Supplements fed to dams during gestation did not influence feedlot performance or carcass characteristics. Prepartum energy supplementation, regardless of energy source or prepartum energy balance, resulted in improved conception rate, but other measures of reproduction, calf and feedlot performance, and carcass characteristics were not affected.     

Effect of undegradable intake protein supplementation on intake, digestion, microbial efficiency, in situ disappearance, and plasma hormones and metabolites in steers fed low-quality grass hay

Four ruminally and duodenally cannulated beef steers (492 +/- 30 kg) were used in a 4 x 4 Latin square design to evaluate the effect of undegradable intake protein (UIP) supplementation on intake, digestion, microbial efficiency, in situ disappearance, and plasma hormones and metabolites in steers fed low-quality grass hay. The steers were offered chopped (10.2 cm in length) grass hay (6.0% CP) ad libitum and 1 of 4 supplements. Supplemental treatments (1,040 g of DM daily), offered daily at 0800, were control (no supplement) or low, medium, or high levels of UIP (the supplements provided 8.3, 203.8, and 422.2 g of UIP/ d, respectively). The supplements were formulated to provide similar amounts of degradable intake protein (22%) and energy (1.77 Mcal of NE(m)/kg). Blood samples were taken at -2, -0.5, 1, 2, 4, 8, 12, and 24 h after supplementation on d 1 (intensive sampling) and at -0.5 h before supplementation on d 2, 3, 4, and 5 (daily sampling) of each collection period. Contrasts comparing control vs. low, medium, and high; low vs. medium and high; and medium vs. high levels of UIP were conducted. Apparent and true ruminal OM and N digestion increased (P < 0.03) in steers fed supplemental protein compared with controls, but there were no differences (P > 0.26) among supplemental protein treatments. There were no differences (P > 0.11) among treatments for NDF or ADF digestion, or total ruminal VFA or microbial protein synthesis. Ruminal pH was not different (P = 0.32) between control and protein-supplemented treatments; however, ruminal pH was greater (P = 0.02) for supplementation with medium and high compared with low UIP. Daily plasma insulin concentrations were increased (P = 0.004) in protein-supplemented steers compared with controls and were reduced (P = 0.003) in steers fed low UIP compared with steers fed greater levels of UIP. Intensive and daily plasma urea N concentrations were increased (P < 0.01) in protein-supplemented steers compared with controls and increased (P < 0.02) for intensive and daily sampling, respectively, in steers supplemented with medium and high UIP compared with low UIP. Supplemental protein increased apparent and true ruminal OM and N digestion, and medium and high levels of UIP increased ruminal pH compared with the low level. An increasing level of UIP increases urea N and baseline plasma insulin concentrations in steers fed low-quality hay.     

Effects of prepartum supplementation of linoleic and mid-oleic sunflower seed on cow performance, cow reproduction, and calf performance from birth through slaughter, and effects on intake and digestion in steers

Two experiments were conducted to determine the effects of sunflower seed supplements with varying fatty acid profiles on performance, reproduction, intake, and digestion in beef cattle. In Exp. 1, 127 multiparous spring-calving beef cows with free-choice access to bermudagrass hay were individually fed 1 of 3 supplements for an average of 83 d during mid to late gestation. Supplements (DM basis) included 1) 1.23 kg/d of a soybean hull-based supplement (control treatment); 2) 0.68 kg/d of linoleic sunflower seed plus 0.23 kg/d of the control supplement (linoleic treatment); and 3) 0.64 kg/d of mid-oleic sunflower seed plus 0.23 kg/d of the control supplement (oleic treatment). During the first 62 d of supplementation, the BW change was 11, 3, and -3 kg for cows fed the control, linoleic, and oleic supplements, respectively (P < 0.001). No difference in BW change was observed during the subsequent period (-65 kg, P = 0.83) or during the entire 303-d experiment (-31 kg, P = 0.49). During the first 62 d of supplementation, cows fed sunflower supplements tended (P = 0.08) to lose more body condition than cows fed the control diet, but BCS was not different (P > 0.22) for any subsequent measurement. At the beginning of the breeding season, the percentage of cows exhibiting luteal activity was greater for cows fed the control diet (43%; P = 0.02) than for cows fed either linoleic (20%) or oleic (16%) supplementation; however, first-service conception rate (67%; P = 0.22) and pregnancy rate at weaning (92%; P = 0.18) were not different among supplements. No differences were detected in calf birth (P = 0.46) or weaning BW (P = 0.74). In Exp. 2, 8 ruminally cannulated steers were used to determine the effects of sunflower seed supplementation on forage intake and digestion. Treatments (DM basis) included 1) no supplement; 2) a soybean hull-based supplement fed at 0.29% of BW/d; 3) whole linoleic sunflower seed fed at 0.16% of BW/d; and 4) whole high-oleic sunflower seed fed at 0.16% of BW/d. Hay intake was not influenced (P = 0.25) by supplement (1.51% of BW/d); however, DMI was greatest (P < 0.01) for steers fed the soybean hull-based supplement (1.93% of BW/d). Sunflower seed supplementation reduced (P < 0.01) NDF and ADF digestibility while increasing (P < 0.01) apparent CP and apparent lipid digestibility. In conclusion, whole sunflower seed supplementation resulted in reduced cow BW gain during mid to late gestation, but this reduction did not influence subsequent cow BW change, pregnancy rate, or calf performance.     

Nonstructural carbohydrate supplementation of yearling heifers and range beef cows

A digestion study with 28 yearling heifers (428 +/- 9.9 kg; Exp. 1) and a 2-yr winter grazing trial with 60 crossbred cows (552 +/- 6.9 kg; Exp. 2) were used to determine the effects of level of nonstructural carbohydrate (NSC) supplementation on intake and digestibility of low-quality forage. Treatments were as follows: 1) control, no supplement; 2) 0.32 kg of NSC (1.8 kg/d of soybean hulls and soybean meal; DM basis); 3) 0.64 kg of NSC (1.7 kg/d of wheat middlings; DM basis); and 4) 0.96 kg of NSC (1.7 kg/d of barley and soybean meal; DM basis). Supplements provided 0.34 kg of CP/d and 5.1 Mcal of ME/d. In Exp. 1, heifers were individually fed hay (5.5% CP, DM basis) and their respective supplements in Calan gates for 28 d. Data were analyzed as a completely randomized design. In Exp. 2, cows were individually fed supplement on alternate days, and grazed a single rangeland pasture stocked at 1.8 ha/ animal unit month. Two ruminally cannulated cows were used per treatment to obtain forage extrusa and to measure in situ DM disappearance (DMD) and carboxymethylcellulase (CMCase) activity of particle-associated ruminal microbes. Data were analyzed as a completely randomized design with the effects of treatment, year, and their interaction. In both experiments, Cr2O3 boluses were used to determine fecal output, individual animal was the experimental unit, and contrasts were used to test linear and quadratic effects of NSC level and control vs. supplemented treatments. In Exp. 1, hay and diet DM, NDF, and CP intakes and digestibilities were increased (P < 0.01) by NSC supplementation compared with the control. In Exp. 2, 72-h in situ DMD and CMCase were decreased linearly (P < 0.08) with increasing NSC supplementation. Intake of forage DM, NDF, and CP was decreased linearly (P < 0.01) with increasing NSC supplementation during both years. Supplementation with NSC decreased (P = 0.01) cow BW loss compared with the control in yr 1, whereas in yr 2, cow BW loss was linearly increased (P = 0.03) by increasing NSC supplementation. Supplements containing NSC improved forage digestion and intake when heifers consumed forage deficient in CP relative to energy (digestible OM:CP > 7), but decreased forage digestion and intake when cows grazed forage with adequate CP relative to energy (digestible OM:CP < 7). Forage and supplement digestible OM:CP seemed to be superior predictors of response to supplementation with NSC compared with forage CP levels alone.     

Efficacy of using a combination of rendered protein products as an undegradable intake protein supplement for lactating, winter-calving, beef cows fed bromegrass hay

Seventy-two (36 in each of two consecutive years) lactating, British-crossbred cows (609 +/- 19 kg) were used to evaluate effects of feeding a feather meal-blood meal combination on performance by beef cows fed grass hay. Bromegrass hay (9.6% CP, DM basis) was offered ad libitum and intake was measured daily in individual Calan electronic headgates. Acclimation to Calan gates began approximately 20 d after parturition, and treatments were initiated 21 d later. Cows were assigned randomly to one of four treatments (DM basis) for 60 d: 1) nonsupplemented control (CON), 2) energy control (ENG; 790 g/d; 100% beet pulp), 3) degradable intake protein (DIP; 870 g/d; 22% beet pulp and 78% sunflower meal), or 4) undegradable intake protein (UIP; 800 g/d; 62.5% sunflower meal, 30% hydrolyzed feather meal, and 7.5% blood meal). Net energy concentrations of supplements were formulated to provide similar NE(m) intakes (1.36 Mcal/d). The DIP and UIP supplements were calculated to supply similar amounts of DIP (168 g/d) and to supply 64 and 224 g/d of UIP, respectively. Forage DMI (kg/d) decreased in supplemented vs. nonsupplemented (P = 0.03) and DIP vs. UIP (P = 0.001); however, when expressed as a percentage of BW, forage DMI was not different (P = 0.23). Supplemented cows tended (P = 0.17) to lose less BW than CON. Body condition change was not affected (P = 0.60) by postpartum supplementation. No differences were noted in milk production (P = 0.29) or in calf gain during the supplementation period (P = 0.74). Circulating insulin concentrations were not affected by treatment (P = 0.42). In addition, supplementation did not affect circulating concentrations of NEFA (P = 0.18) or plasma urea nitrogen (P = 0.38). Results of the current study indicate that supplementation had little effect on BW, BCS, milk production, or calf BW when a moderate-quality forage (9.6% CP) was fed to postpartum, winter-calving cows in optimal body condition (BCS > 5). Supplemental UIP did not enhance cow performance during lactation. Forage UIP and microbial protein supply were adequate to meet the metabolizable protein requirements of lactating beef cows under the conditions of this study.     

Effect of crambe meal on performance, reproduction, and thyroid hormone levels in gestating and lactating beef cows

Crambe meal was compared to a combination of sunflower and soybean meal as a protein supplement for mature beef cows in two experiments. In Exp. 1, cows (n = 80, average BW 651+/-14.4 kg) were fed crambe meal at 9.86% of dry matter intake (DMI) during the last trimester of gestation. No differences (P < .05) were detected due to treatment for cow weight, condition score, thyroid hormones, calf birth weight, or calving interval. In Exp. 2, cows (n = 100, average BW 566+/-6.82 kg) were fed crambe meal at 7.44% of DMI during the last trimester of gestation and at 8.33% of DMI during early lactation (53+/-6 d of lactation). Gains were greater during gestation (P = .09) and throughout the supplementation period (P = .06), and days to first estrus were reduced (P < .01) for cows fed crambe meal. During lactation, serum triiodothyronine (T3) concentrations did not decline as much (P = .03) in cows fed crambe meal as in cows fed sunflower-soybean meal-based supplements. No differences (P > .10) were apparent for condition score, birth weight, calf growth rate, weaning weight, thyroid hormones during gestation, or calving interval. These data indicate that crambe meal fed at the levels used in this experiment can be used as a protein supplement for beef cows without negatively affecting cows' performance.     

Effects of supplementation on intake, digestion, and performance of beef cattle consuming fertilized, stockpiled bermudagrass forage

Experiments were conducted to determine the effects of increasing supplement protein concentration on performance and forage intake of beef cows and forage utilization of steers consuming stockpiled bermudagrass forage. Bermudagrass pastures were fertilized with 56 kg of N/ha in late August. Grazing was initiated during early November and continued through the end of January each year. Treatments for the cow performance trials were: no supplement or daily equivalents of 0.2, 0.4, and 0.6 g of supplemental protein per kilogram of BW. Supplements were formulated to be isocaloric, fed at the equivalent of 0.91 kg/d, and prorated for 4 d/wk feeding. Varying the concentration of soybean hulls and soybean meal in the supplements created incremental increases in protein. During yr 1, supplemented cows lost less weight and condition compared to unsupplemented animals (P < 0.05). During yr 2, supplemented cows gained more weight (P = 0.06) and lost less condition (P < 0.05) compared to unsupplemented cows. Increasing supplement protein concentration had no affect on cumulative cow weight change or cumulative body condition score change. Forage intake tended to increase (P = 0.13, yr 1 and P = 0.07, yr 2) in supplemented cows. Supplement protein concentration did not alter forage intake. In a digestion trial, four crossbred steers were used in a Latin square design to determine the effects of supplement protein concentration on intake and digestibility of hay harvested from stockpiled bermudagrass pasture. Treatments were no supplement; or 0.23, 0.46, and 0.69 g of supplemental protein per kilogram of BW. Forage intake increased (P < 0.05) 16% and OM intake increased (P < 0.01) 30% in supplemented compared to unsupplemented steers. Diet OM digestibility increased (P = 0.08) 14.5% and total digestible OM intake increased (P < 0.05) 49% in supplemented compared to unsupplemented steers. Supplement protein concentration did not alter forage intake, total digestible OM intake, or apparent digestibility of OM or NDF. During the initial 30 d after first killing frost, beef cows did not respond to supplementation. However, later in the winter, supplementation improved utilization of stockpiled bermudagrass forage.     

Estimated copper requirements of angus and simmental heifers

In Exp. 1, Simmental (n = 21) and Angus (n = 21) heifers, approximately 9 mo of age, were used in a 160-d study to determine the effect of dietary Cu on growth and Cu status. Two- or three-yr-old first-calf heifers (21 Angus and 21 Simmental) entering into their last trimester of pregnancy were used in Exp. 2 to estimate Cu requirements of the two breeds during gestation and early lactation. Treatments in both studies consisted of 0 (control), 7, or 14 mg of supplemental Cu (as CuSO4)/kg of DM. The control corn silage-based diets contained 6.4 and 4.4 mg of Cu/kg of DM in Exp. 1 and 2, respectively, and 1.2 mg of Mo/kg. Dietary Cu did not affect performance in either breed in Exp. 1. Copper supplementation generally did not affect plasma Cu concentrations in Angus heifers, but increased (P < 0.05) plasma Cu in Simmental heifers from d 37 until the end of Exp. 1. Final liver Cu concentrations were lower (P < 0.05) than initial concentrations in control Angus and Simmental heifers; however, liver Cu increased (P < 0.01) in Cu-supplemented heifers. In Exp. 2, Cu supplementation of the control diet increased (P < 0.05) plasma Cu during gestation and greatly increased (P < 0.01) liver Cu in both breeds. Calves born to cows not supplemented with Cu also had lower plasma Cu concentrations than Cu-supplemented calves by 73 d of age. In both studies, control Simmental heifers had lower (P < 0.05) plasma Cu concentrations than Angus on most sampling dates. When Cu was supplemented at 7 or 14 mg/kg of DM,few differences in plasma Cu concentrations were observed between breeds. Results suggest that Angus heifers have a lower minimal Cu requirement than Simmental. Based on liver Cu, the control diets containing 4.4 or 6.4 mg of Cu/kg of DM did not meet the Cu requirement of either breed during gestation and lactation or growth. Addition of 7 mg of Cu/kg of DM to the control diets met Cu requirements of both breeds.     

Effects of supplemental protein type on intake, nitrogen balance, and site, and extent of digestion in whiteface wethers consuming low-quality grass hay

Two experiments were conducted to determine the effects of supplementing ruminally degradable intake protein (DIP) or ruminally undegradable intake protein (UIP) on N balance (Exp. 1; n = 6 wethers; initial BW = 48.7 +/- 4.6 kg) and site and extent of digestion (Exp. 2; n = 5 wethers; initial BW = 36.9 +/- 3.1 kg) in whiteface wethers consuming (as-fed basis) 69% blue grama and 31% love grass hay (mixture = 7.5% CP, 73.0% NDF, 36.0% ADF [DM basis]). Treatments were 1) no supplement (Control), 2) a supplement (219 g/d, as-fed basis) low in UIP (70 g/d of CP; 24.8 g/d of UIP), and 3) a supplement (219 g/d, as-fed basis) high in UIP (70 g/d of CP; 37.1 g/d of UIP). Both experiments were replicated 3 x 3 Latin square designs, with identical feeding and supplementation. Wethers had ad libitum access to the forage mixture and fresh water, and received supplement once daily. In Exp.1, forage intake (percentage of BW) was greatest (P = 0.04) for control, but total DMI (g/d) was greatest (P = 0.05) for lambs consuming supplement. Apparent total-tract OM digestibility was numerically greater (P = 0.11) for supplemented wethers than for controls, whereas total-tract ADF digestibility tended (P = 0.08) to be greater for control wethers. Lambs fed supplements consumed and retained more (P < or = 0.01) N (% of N intake) compared with controls, but no difference (P = 0.22) was observed between low and high UIP treatments. Similar to Exp. 1, forage intake (percentage of BW) tended (P = 0.06) to be greater for control than for supplemented wethers in Exp. 2. Ruminal NDF digestibility was 16.3% greater (P = 0.02) for supplemented wethers than for controls. Postruminal NDF and N digestibilities were greatest (P < or = 0.03) for controls, but apparent OM digestibility did not differ among treatments at all sites. Duodenal N flow was greatest (P = 0.05) for high UIP and least for control wethers. Nonmicrobial N flow was greater (P = 0.02) for high UIP compared with low UIP or controls. Control wethers had greater (P = 0.05) microbial efficiency. Ruminal ammonia concentration tended (P = 0.08) to be greatest for wethers fed low UIP and least for controls, with high-UIP wethers having intermediate ammonia concentrations. Results from these experiments suggest that in lambs fed low-quality forage there was no difference in apparent total-tract digestion or N balance (percentage of N intake) between lambs fed supplements that had the same CP but differed in the proportion of UIP and DIP; however, supplementing protein (regardless of UIP:DIP ratio) to wethers consuming low-quality forage increased N balance.     

Effects of body condition score at calving and feeding various types of concentrate supplements to grazing dairy cows on early lactation performance

The objective of the experiment reported here was to establish the effect of canola meal supplements of different protein degradability on the performance of grazing dairy cows with different body condition scores (BCS) in early lactation, and to compare this with feeding a cereal grain supplement instead. The experiment included a total of 72 cows in six treatments in a 2 ^* 3 factorial design, incorporating two BCS at calving (4.1 and 5.6 units on an 8-point scale), and three early lactation pelleted supplements. The three pelleted supplements were 100% wheat (wheat supplement), 50% wheat and 50% untreated mechanically extracted canola meal (a rumen degradable protein supplement), and 50% wheat and 50% canola meal that had been subjected to additional heat and pressure (a rumen undegradable protein supplement). It was hypothesised that fat cows would perform best with the treated canola meal supplement, which provided most rumen undegradable protein, whereas the type of protein would not be important for thin cows, and neither would the type of supplemental energy. Cows grazed pasture after calving at a daily pasture allowance of 35–40 kg DM/cow and were offered 6 kg concentrates each day. Cows were fed these diets for 92 days on average, from calving until three weeks into the mating period. Both canola meal-based supplements resulted in higher (P < 0.05) daily milk production than the wheat supplement (33.3 and 34.0 v. 30.5 kg/cow) in both thin and fat cows. Body condition score at calving positively (P < 0.05) affected average milk yield (31.6 v. 33.7 kg/cow), however, there was a time × BCS × supplement interaction whereby the fatter cows benefited from the use of either of the canola meal supplements for a longer period than did the thin cows. Average milk fat concentrations were greater (P < 0.05) where the canola meal supplements were fed (39.3 and 39.6 v. 35.6 g/kg), and in fat cows relative to thin cows (40.0 v. 36.3 g/kg). Serum urea concentrations were significantly (P < 0.05) lower in cows fed wheat than in those fed either of the canola meal supplements (3.1 v. 4.3 and 4.2 mmol/L). Serum β-hydroxybutyrate concentrations were lowest (P < 0.05) where wheat pellets were fed, and highest (P < 0.05) where treated canola meal pellets were fed, and plasma glucose concentrations were highest with wheat and lowest with the treated canola meal pellets. Thus, the hypothesis was not supported by the results of this experiment.     

Effect of selenate as a feed supplement to dairy cows in comparison to selenite and selenium yeast

The main aim of this trial was to define the possible differences between selenite and selenate in their ability to increase the selenium (Se) concentration of milk, in comparison with organic Se. Dairy cows (n = 42) were fed a basal diet containing .10 to .12 mg Se/kg DM for 5 mo and were then divided into four groups of 10 or 11, as similar as possible in age and stage of lactation. During the next 84 d, the cows in three of the groups were supplemented with 3 mg of Se daily, whereas the cows in one control group remained unsupplemented. The Se supplement was given as sodium selenite, sodium selenate, or a Se yeast product. The total Se concentration of the diets varied with the cows' stage of lactation and was for the supplemented groups .24 to .31 mg/kg DM, but remained between .10 and .12 mg/kg in the control group. At the end of the trial, the mean whole blood Se concentrations in the selenite, selenate, yeast, and control groups were 138, 141, 165, and 104 microg/L, respectively. The Se concentration in plasma apparently reached a plateau level within 4 wk, at approximately 75 microg/L in the selenite group, 80 microg/L in the selenate group, and 90 microg/L in the yeast group. In the control group the mean concentration in plasma remained at approximately 50 microg/L. The increase of the activity of glutathione peroxidase (GSH-Px) in the erythrocytes was significantly higher in the supplemented groups than in the control group. The mean concentrations of Se in milk in the selenite, selenate, and yeast groups were 16.4, 16.4, and 31.2 microg/L, respectively, whereas the concentration remained at approximately 14 microg/L in the control group. The milk Se concentration reached a plateau within 1 wk after the start of Se supplementation. Dietary supplementation with selenite and selenate, thus, had only a limited effect on the Se concentration in milk, and there was no significant difference between the two inorganic compounds in any variable measured. Organic Se was much more effective than inorganic Se in increasing the concentration of Se in milk.     

Effects of dietary arginine supplementation during gestation and lactation on the performance of lactating primiparous sows and nursing piglets

A 2 x 2 factorial arrangement of treatments in a randomized block design was used to determine the effects of dietary Arg supplementation during gestation and lactation on the lactation performance of 38 first-parity sows. At 30 d of gestation, pregnant gilts were allotted based on BW to 1 of 2 diets supplemented with 1% L-Arg.HCl or 1.7% L-Ala (isonitrogenous control). After farrowing, sows were further allotted based on BW within previous gestation treatment groups to 1 of 2 lactation diets supplemented with 1% L-Arg.HCl or 1.7% L-Ala (isonitrogenous control). All gestation diets contained 3.1 Mcal/kg and 12.2% CP (as is) and were fed 2 kg/d in 2 equally sized meals, whereas all lactation diets contained 3.2 Mcal/kg and 18.6% CP (as is) and were fed ad libitum. Litter size was standardized to 10 piglets by cross-fostering within 24 h postfarrowing. On a weekly basis, BW and backfat (BF) thickness of sows, as well as piglet BW were measured, and blood and milk samples were obtained from the sows. Number of days from weaning to estrus and ADFI were also recorded. There were no differences in BW, BF thickness, ADFI, or days until return to estrus among treatment groups. There was no effect of the gestation diet or a gestation x lactation diet interaction on any parameter measured. On d 7 of lactation, plasma concentrations of Arg and insulin in sows, as well as concentrations of most AA in milk, were greater (P < 0.05) in response to Arg supplementation during lactation compared with the control. Weight gain of piglets from sows fed the Arg-supplemented diet during lactation was greater between d 0 and 7 (P < 0.01) and between d 0 and 21 (P < 0.05) of lactation compared with piglets from sows fed the control diet. Collectively, results from this study indicate the potential beneficial effects of dietary Arg supplementation in improving the lactation performance of first-parity sows.     

Increasing selenium supply during the close-up dry period improves nutrient metabolism and attenuates inflammatory response after calving in dairy cows

The objective of this study was to investigate whether feeding selenium (Se)-replete cows a Se-yeast supplement in late pregnancy affects nutrient metabolism and inflammatory response during the periparturient period. Twenty cows were randomly assigned to two groups with 10 cows each. Cows in one group received Se-yeast at 0.3 mg Se/kg DM during the last 4 weeks before calving in addition to fed a TMR containing supplemented sodium selenite at 0.3 mg Se/kg DM (Se-yeast), while cows in another group were only fed a TMR containing supplemented sodium selenite at 0.3 mg Se/kg DM (Control). Blood samples were collected and analyzed for nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), glucose, insulin, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, serum amyloid A (SAA), haptoglobin (Hp), and albumin. In control cows, plasma NEFA, IL-1β, IL-6, SAA, and Hp levels increased after calving, but glucose, insulin, and albumin levels decreased after parturition. Se-yeast supplemental cows had lower postpartum concentrations of NEFA, TNF-α, IL-1β, IL-6, SAA, and Hp, and higher postpartum levels of glucose, insulin, and albumin compared with control cows. The results indicate that feeding Se-replete cows a Se-yeast supplement in late pregnancy improves nutrient metabolism and attenuates the inflammatory response after calving.     

Poultry Manure as a Supplement in High Concentrate Diets Limit-Fed to Beef Cows

Three trials were conducted to evaluate poultry manure as a CP and mineral supplement in high concentrate diets limit-fed to gestating and lactating beef cows and heifers. Trial 1 used 67 pregnant Simmental x Angus beef cows (BW, 640 ± 6 kg). During this 126-d trial, no differences (P>0.10) in BW changes or body condition scores (BCS) were observed between cows provided supplemental CP and minerals from either poultry manure or a soybean meal-based protein and mineral supplement. Feed costs per day were lower for cows fed diets supplemented with poultry manure ($0.82) than for those fed diets supplemented with the soybean meal-based protein and mineral supplement ($1.11) and were much lower than those for cows fed an all hay diet offered for ad libitum intake ($1.46). In Trial 2, 26 pregnant Simmental x Angus beef heifers (BW, 503 ± 11 kg) were used to determine the efficacy of poultry manure as a source of energy, protein, and minerals. No differences (P>0.10) in performance were observed between heifers consuming a low poultry manure diet (4.6 kg/d corn and 1.1 kg/d poultry manure) or a high poultry manure diet (3.1 kg/d corn and 3.2 kg/d poultry manure). Feed costs per day were lower for heifers on the high poultry manure treatment ($0.61 vs $0.73 for high and low poultry manure treatments, respectively). Trial 3 was conducted with 61 beef cows and 23 beef heifers in late gestation. Animals consuming the poultry manure-supplemented, corn-based diet lost more weight during both the gestation (P<0.10) and lactation periods (P<0.05) than those fed the soybean meal-based protein and mineral supplement. Overall BCS change was similar among treatments (P=0.31). Feed costs per day were lower for cows fed supplemental poultry manure ($0.82) than for those fed the soybean meal-based protein and mineral supplement ($1.11). Poultry manure was a more economical source of supplemental CP and minerals than a soybean meal-based protein and mineral supplement when fed to meet nutrient needs of cows that were limit-fed a corn-based diet. Effects on cow performance were minimal.     

Effects of supplement type on performance, reproductive, and physiological responses of Brahman-crossbred females

Two experiments were conducted to compare the performance and physiological responses of forage-fed beef females supplemented with either a molasses-based (ML) or a citrus pulp-based (CT) supplement. In Exp. 1, BW gain, reproductive performance, and concentrations of blood urea N (BUN), plasma glucose, insulin, IGF-I, and progesterone (P4) were assessed in 60 Brahman x Angus heifers supplemented 3 times weekly with either ML or CT. Supplement intakes were formulated to be isocaloric and isonitrogenous. Reproductive performance was not affected by treatments, but mean BW gain was greater (P < 0.01) for heifers fed CT than for those fed ML (0.40 vs. 0.30 kg/d). Mean plasma concentrations of glucose, insulin, and IGF-I were greater (P < 0.05) for heifers fed CT, whereas BUN was greater (P < 0.05) for heifers fed ML. Mean plasma P4 concentration did not differ between treatments, but both groups had lower plasma P4 concentrations during days that supplements were offered (P < 0.01). In Exp. 2, forage DMI and concentrations of BUN, plasma glucose, insulin, IGF-I, and P4 were assessed in 24 Brahman x British mature cows supplemented with the same treatments described in Exp. 1. Overall forage DMI did not differ between treatments, but a day effect and a treatment x day interaction were detected (P < 0.05). Both groups consumed less forage during the days on which the supplements were offered (P < 0.01), and forage DMI for cows fed CT was less (P < 0.05) than for cows fed ML during those days. No differences were detected in any blood or plasma measurement. In addition, no differences in concentrations of P4 were detected between CT- and ML-fed cows. We concluded that CT-supplemented heifers had greater BW gain compared with ML-supplemented heifers, but no differences in reproductive performance were observed. We also observed that CT-supplemented cows had a greater variability in forage DMI compared with ML-supplemented cows.     

Influence of nutrient intake and body fat on concentrations of insulin-like growth factor-I, insulin, thyroxine, and leptin in plasma of gestating beef cows

Pregnant Angus x Hereford cows (n = 73) were used to determine the effects of amount of nutrient intake and BCS on concentrations of IGF-I, insulin, leptin, and thyroxine in plasma. At 2 to 4 mo of gestation, cows were blocked by BCS and assigned to one of four nutritional treatments: high (H = a 50% concentrate diet fed ad libitum in a drylot) or adequate native grass pastures and one of three amounts of a 40% CP supplement each day (M = moderate, 1.6 kg; L = low, 1.1 kg; or VL = very low, 0.5 kg; as-fed basis). After 110 d of treatment, all cows grazed dormant native grass pasture and received 1.6 kg/d of a 40% CP supplement. At 68, 109, and 123 d of treatment, cows were gathered, and plasma samples were collected by tail venipuncture (fed sample). After 18 h without feed and water, a second plasma sample was collected (fasted sample). At 109 d of treatment, BCS was greatest (P < 0.05) for H cows, similar for M and L cows, and least for VL cows. Concentrations of insulin and leptin were greater (P < 0.05) for H cows than for M and VL cows at 68 and 109 d, but similar for all groups at 123 d. Thyroxine in plasma was greatest (P < 0.05) for H cows at 68 d and similar for cows on all treatments at 123 d. Concentrations of IGF-I, insulin, and leptin in fed and fasted cows were positively correlated with BCS at 109 d. Body condition was predictive of concentrations of IGF-I, insulin, and leptin when cows had different nutrient intakes, but BCS accounted for less than 12% of the variation in plasma concentrations of IGF-I, insulin, and leptin when nutrient intake was the same for all cows. We conclude that amount of nutrient intake has a greater influence than body energy reserves on IGF-I, insulin, and leptin concentrations in the plasma of gestating beef cows.     

Influence of DL-methionine supplementation on growth, ruminal fermentation and dilution rates in heifers

A 3 X 3 replicated Latin square design was used to evaluate three isonitrogenous supplements designed to supply 250 g crude protein (CP) daily. Measurements included in situ dry matter (DM) and neutral detergent fiber (NDF) fermentation and ruminal dilution rates. Supplements contained beet pulp plus DL-methionine and urea (MET), ammonium sulfate and urea (U) or soybean meal (SBM). Six mature, ruminally cannulated crossbred beef cows were individually fed supplement and a mixture (63% NDF and 6.1% CP) of chopped 75% grass hay and 25% barley straw in ad libitum. Fermentation rate of DM was increased (P less than .05) by 30% with MET in comparison to SBM or U (9.54 vs 7.28% and 7.74%/h for MET, SBM and U, respectively). Even though MET improved fermentation rate by 30%, particle dilution rate was more important in affecting ruminal digestibility than fermentation rate. Two 90-d heifer growth trials were conducted to evaluate similar supplements. Supplements similar to those used in the in situ trial were mixed with roughage to provide a complete diet balanced for .3 kg daily gain. Heifers consumed 112% of the National Research Council CP requirement. Weight gain, intake and feed conversion were similar (P greater than .10) for all treatments. In heifer trial 2, 90% of the National Research Council CP requirement was fed. The heifers supplemented with MET and SBM had faster (P less than .05) weight gains than heifers receiving U. These studies show that feeding DL-methionine with urea, as compared with feeding an isonitrogenous supplement containing SBM, increased the fermentation rate of DM.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of dietary omega fatty acids on pregnancy rate,plasma prostaglandin metabolite levels,serum progesterone levels,and milk fatty-acid profile in beef cows

The objectives were to determine the effects of feeding supplements rich in omega-6 or omega-3 fatty acids (FA) during the late gestation to the early postpartum and breeding periods on reproduction and milk FA profile in beef cows. For each of two years, at the beginning of period 1 (mid-December), 72 beef cows, calving in January or February, were assigned to diets supplemented with roasted flaxseed (Flax) or roasted soybean (Soybean). For each of two years, after 11 wk (end of period 1), 18 cows of 36 in the Flax group were switched to the soybean supplement and 18 cows of 36 in the Soybean group were switched to the flax supplement (start of Period 2). Cows were bred by timed artificial insemination (TAI) in week 5 of period 2. The FA composition of the milk reflected the FA profile of the oilseed supplements. There were no differences in pregnancy rates among the 4 groups. The treatments had no effect on plasma prostaglandin metabolite levels or ratios at 4 to 11 d postpartum. At 5 to 6 d post- TAI, pregnant cows fed Flax in period 1 had lower (P < 0.05) plasma prostaglandin F metabolite (PGFM) levels and PGFM to prostaglandin E metabolite (PGEM) ratio than cows fed Soybean, but there were no significant differences at 19 to 20 d post-TAI. Cows pregnant from TAI and fed Flax in period 2 had higher (P < 0.05) serum progesterone levels at 5 to 6 d post-TAI than cows fed Soybean, but there was no difference at 19 to 20 d post-TAI. The dietary treatments had no effect on pregnancy rates, but there were some effects on plasma PGFM levels, PGFM to PGEM ratios, and serum progesterone levels. The FA supplements influenced the FA composition of milk.