173 Grazing Cover Crops: Effects of Cattle Removal Date on Forage Production and Cattle Performance

Use of cool-season annual cover crops through grazing has been shown to be a potential tool in extending the grazing season, while still mitigating environmental risks associated with warm-season row crop production. Although data describing the effects of grazing on soil health are not novel, effects of grazing length on animal performance and cover crop production are limited. The objective was to determine cattle performance and forage production when grazing a cool-season annual cover-crop. Twelve, 1.2-ha pastures were established in a four species forage mix and randomly allocated to be grazed through either mid-February (FEB), mid-March (MAR), or mid-April (APR) with a non-grazed control (CON). Three tester steers were randomly placed in each paddock and a 1:1 forage allowance was maintained in each paddock using put-and-take steers. Animals were weighed every 30 d for determination of average daily gain (ADG). Forage was harvested bi-weekly and analyzed for forage production, neutral detergent fiber (NDF), and acid detergent fiber (ADF). Fiber fractions were measured using an ANKOM fiber analyzer (ANKOM Tech, Macedon, NY). All data were analyzed using MIXED procedure of SAS version 9.4 (SAS Inst., Cary, NC). Differences in forage mass were detected between CON and FEB (3,694.75 vs. 2,539.68 kg/ha; P < 0.003), CON and MAR (3,694.75 vs. 1,823.45 kg/ha; P < 0.001), and CON and APR (3,694.75 vs. 1,976.23 kg/ha; P < 0.001). Differences in total gain/acre were detected between APR and MAR (212.24 vs. 101.74 kg/ha; P < 0.0001), APR and FEB (212.24 vs 52.65 kg/ha; P < 0.0001), and FEB and MAR (101.74 vs. 52.65 kg/ha; P < 0.003). No differences were detected for tester ADG (1.23 kg/day, P = 0.56), NDF (44.9%, P = 0.99), or ADF (27.2%, P = 0.92) among treatments. These results indicate that cattle removal date effected forage yield and total gain/hectare.

Influence of Molybdenum in Drinking Water or Feed on Copper Metabolism in Cattle—A Review

The majority of Mo research has focused on the antagonist effect of Mo, alone or in combination with elevated dietary S, on Cu absorption and metabolism in ruminants. Diets containing both >5.0 mg of Mo/kg DM and >0.33% S have been reported to reduce the Cu status in cattle and sheep. Therefore, due to the potential for inducing Cu deficiency, Mo and S concentrations in the diet should be monitored and kept within appropriate values. Elevated sulfate concentrations in drinking water can also be detrimental to livestock production, especially in ruminants. High concentrations of sulfate in water have been extensively studied in cattle because high-sulfate water induces polioencephalomalacia in ruminants. However, little research has been conducted investigating the impact of Mo in water on Cu metabolism in ruminants. Based on the limited number of published experiments, it appears that Mo in drinking water may have a lower antagonistic impact on the Cu status in cattle when compared to Mo consumed in the diet. This response may be due to a certain percentage of water bypassing the rumen when consumed by ruminants. Therefore, the objective of this review was to examine the impact of Mo in drinking water on cattle performance and Mo and Cu metabolism.

A meta-analysis of effects of dietary seaweed on beef and dairy cattle performance and methane yield

There has been considerable interest in the use of red seaweed, and in particular Asparagopsis taxiformis, to increase production of cattle and to reduce greenhouse gas emissions. We hypothesized that feeding seaweed or seaweed derived products would increase beef or dairy cattle performance as indicated by average daily gain (ADG), feed efficiency measures, milk production, and milk constituents, and reduce methane emissions. We used meta-analytical methods to evaluate these hypotheses. A comprehensive search of Google Scholar, Pubmed and ISI Web of Science produced 14 experiments from which 23 comparisons of treatment effects could be evaluated. Red seaweed (Asparagopsis taxiformis) and brown seaweed (Ascophyllum nodosum) were the dominant seaweeds used. There were no effects of treatment on ADG or dry matter intake (DMI). While there was an increase in efficiency for feed to gain by 0.38 kg per kg [standardized mean difference (SMD) = 0.56; P = 0.001] on DerSimonian and Laird (D&L) evaluation, neither outcome was significant using the more rigorous robust regression analysis (P >0.06). The type of seaweed used was not a significant covariable for ADG and DMI, but A. nodosum fed cattle had lesser feed to gains efficiency compared to those fed A. taxiformis. Milk production was increased with treatment on weighted mean difference (WMD; 1.35 ± 0.44 kg/d; P <0.001); however, the SMD of 0.45 was not significant (P = 0.111). Extremely limited data suggest the possibility of increased percentages of milk fat (P = 0.040) and milk protein (P = 0.001) on (D&L) WMD evaluation. The limited data available indicate dietary supplementation with seaweed produced a significant and substantial reduction in methane yield by 5.28 ± 3.5 g/kg DMI (P = 0.003) on D&L WMD evaluation and a D&L SMD of −1.70 (P = 0.001); however, there was marked heterogeneity in the results (I2 > 80%). In one comparison, methane yield was reduced by 97%. We conclude that while there was evidence of potential for benefit from seaweed use to improve production and reduce methane yield more in vivo experiments are required to strengthen the evidence of effect and identify sources of heterogeneity in methane response, while practical applications and potential risks are evaluated for seaweed use.

The Influence of Residual Feed Intake and Cow Age on Beef Cattle Performance, Supplement Intake, Resource Use, and Grazing Behavior on Winter Mixed-Grass Rangelands

The objectives of this study were to evaluate the influence of RFI and cow age on the supplement intake and grazing behavior of beef cattle. Average daily supplement intake (kg/cow/d) displayed an RFI × cow age interaction (p < 0.01), with a linear increase in average daily supplement intake with increasing RFI of 3-year-old cows (p < 0.01). Average daily supplement intake (g ∙ kg BW−1 ∙ d−1) displayed an RFI × cow age interaction (p < 0.01), with a quadratic effect on supplement intake of 3-year-old cows (p = 0.01). Cow age displayed a quadratic effect on variation of supplement intake (p < 0.01), where 1-year-old cows had a greater CV of supplement intake than all other cow ages (p < 0.01). Distance traveled displayed a cow age × RFI interaction (p = 0.02), where high-RFI 5-year-old cows traveled further per day than low 5-year-old RFI cows. The probability of grazing site selection was influenced by cow age (p ≤ 0.03). In summary, heifer post-weaning RFI had minimal effects on beef cattle performance, grazing behavior, or resource utilization; however, cow age impacted both grazing behavior and resource use.

The Effects of Varying Levels of Trace Mineral Supplementation on Feedlot Cattle Performance and Carcass Characteristics

The objective of this experiment was to determine the effects of 4 levels of trace mineral supplementation on feedlot cattle. Two hundred and forty Angus crossbred steers (n = 48, BW = 291 ± 27 kg) were stratified by arrival BW and source and randomly assigned to 1 of 4 experimental treatments in a randomized complete block design (12 pens/ treatment; 5 steers/pen). Cattle went through a 35 d depletion period prior to the administration of treatments where cattle received a supplement that included zero trace minerals and was formulated to meet or exceed other nutrient requirements not met by the ration. Cattle were administered treatments after transition to the finishing ration. The treatments included a negative control (CON) which contained no added trace minerals, a requirement treatment (1X) in which cattle received added trace minerals at requirement levels indicated by NASEM (Co 0.15 mg/kg, Cu 10 mg/kg, Fe 50 mg/kg, I 0.5 mg/kg, Mn 20 mg/kg, Se 0.1 mg/kg, Zn 30 mg/kg; NASEM 2016), a 2 times requirement levels (2X) treatment, and a treatment at four times requirement (4X) levels recommended by the NASEM. Iron was kept constant at 50 mg/kg for 1X, 2X, and 4X treatments. Due to feeding laws, Selenium was included at 0.1, 0.2, and 0.3 mg/kg for 1X, 2X, and 4X respectively. Treatment levels were chosen based on the 2015 Feedlot Consulting Nutritionist Survey. There was no difference in BW, ADG, overall DMI and G:F over the course of the experiment (Linear P ≥ 0.12; Quadratic P ≥ 0.17; CON vs Supplements P ≥ 0.47) There was no difference in marbling score, yield grade, back fat, REA, HCW, or dressing percentage between treatments (Linear P ≥ 0.23; Quadratic P ≥ 0.36; CON vs Supplements P ≥ 0.30). In conclusion, the lack of or addition of supplemented trace minerals at or above indicated requirement levels has no effect on cattle performance or carcass characteristics.