scholarly journals Administering an appeasing substance to beef calves at weaning to optimize productive and health responses during a 42-d preconditioning program

2020 ◽  
Vol 98 (9) ◽  
Author(s):  
Kelsey M Schubach ◽  
Reinaldo F Cooke ◽  
Courtney L Daigle ◽  
Alice P Brandão ◽  
Bruna Rett ◽  
...  

Abstract This experiment evaluated the impacts of administering a bovine appeasing substance (BAS) to beef calves at weaning on their performance, physiological responses, and behavior during a 42-d preconditioning program. Eighty calves (40 heifers and 40 steers; 90% British × 10% Nellore) were weaned at 233 ± 2 d of age (day 0); ranked by sex, weaning age, and body weight (BW); and assigned to receive BAS (IRSEA Group, Quartier Salignan, France; n = 40) or placebo (diethylene glycol monoethyl ether; CON; n = 40). Treatments (5 mL) were topically applied to the nuchal skin area of each animal following dam separation. Within treatment, calves were allocated to one of eight drylot pens (four pens per treatment; pen being the experimental unit) and received a free-choice total mixed ration (TMR) from day 0 to 42, intake of which was assessed daily. Live behavior observations were conducted on days 1, 2, 4, 8, 16, and 32. Temperament was assessed and blood samples were collected via jugular venipuncture on days −21, 0, 3, 7, 14, 28, and 42. Hair samples were collected from the tail switch on days 0, 14, 28, and 42. Calves were vaccinated against bovine respiratory disease viruses on days −21 and 0. Average daily gain from day 0 to 42 did not differ between treatments (P = 0.57) but was greater (P = 0.05) in BAS vs. CON calves from day 0 to 28. Intake of TMR was greater (P = 0.05) during the first week for BAS vs. CON calves (treatment × week; P = 0.08). The mean proportion of calves feeding simultaneously and performance of social and play behaviors were greater (P ≤ 0.05) for BAS vs. CON calves. Escape attempts were greater (P < 0.01) for BAS vs. CON calves on day 1 (treatment × day; P = 0.03). Exit velocity was greater (P = 0.04) for CON vs. BAS calves on day 14 and tended (P = 0.10) to be greater for CON vs. BAS calves on day 7 (treatment × day; P = 0.03). Mean plasma concentrations of haptoglobin were greater (P = 0.02) in CON vs. BAS calves. Hair cortisol concentrations were greater (P = 0.05) in CON vs. BAS calves on day 14 (treatment × day; P = 0.03). Mean serum concentrations of antibodies against bovine viral diarrhea virus were greater (P = 0.02) in BAS vs. CON calves. Collectively, BAS administration to beef calves at weaning alleviated stress-induced physiological reactions, improved temperament evaluated via chute exit velocity, enhanced humoral immunity acquired from vaccination, and appeared to have accelerated adaptation to novel management scheme and environment.

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 194-194 ◽  
Author(s):  
Kelsey Schubach ◽  
Reinaldo F Cooke ◽  
Alice Brandão ◽  
Bruna Rett ◽  
Vitor Ferreira ◽  
...  

Abstract This experiment evaluated the impacts of bovine appeasing substance (BAS) administration on performance, behavioral, and physiological responses of beef calves upon weaning. Eighty Angus-influenced calves (40 heifers, 40 steers) were weaned at 233 ± 2 d of age (d 0), ranked by age and body weight (BW), and assigned to receive BAS (Nutricorp, Araras, SP, Brazil; n = 40) or placebo (diethylene glycol monoethyl ether; CON; n = 40). Treatments (5 mL) were topically applied to the nuchal skin area of each animal. Within treatment, calves were allocated to 1 of 8 drylot pens (4 pens/treatment) and received a free-choice total mixed ration (TMR) from d 0 to 42, intake of which was assessed daily. On d 0, calves were fitted with a pedometer behind their right shoulder, and pedometer results were recorded weekly during the experiment (d 0 to 42) concurrently with full BW collection and temperament evaluation. Blood samples were collected on d 0, 3, 7, 14, 28, and 42, and hair samples were collected from the tail switch on d 0, 14, 28, and 42. Average daily gain from d 0 to 42 did not differ between treatments (P = 0.52), but was greater (P = 0.05) in BAS vs. CON calves from d 0 to 28. Intake of TMR was greater during the first week for BAS vs. CON calves (P = 0.05), and similar (P ≥ 0.44) from wk 2 to 6 (treatment × week; P = 0.08). Exit velocity was greater (P = 0.03) for CON vs. BAS calves on d 14 and tended (P = 0.08) to be greater for CON vs. BAS calves on d 7 (treatment × day; P = 0.04). Physical activity was greater for CON vs. BAS calves on d 1 (P < 0.01), but greater (P = 0.01) in BAS vs. CON on d 2 (treatment × day; P = 0.01). Mean plasma concentrations of haptoglobin were greater (P = 0.03) in CON vs. BAS calves during the experiment. Hair cortisol concentrations were greater (P = 0.0 5) in CON vs. BAS calves on d 14 (treatment × day interaction; P = 0.03). Results from this experiment indicate BAS calves habituated to their environment more rapidly through increased physical activity, which facilitated a lessened stress response associated with weaning, and accelerated adaptation to a novel environment. This was manifested through improved TMR intake and BW gain during the initial period of the experiment. Collectively, results suggest use of BAS as a strategy to improve calf welfare and productivity upon weaning.


2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 193-193
Author(s):  
Eduardo Colombo ◽  
Reinaldo F Cooke ◽  
Alice Brandão ◽  
Jacob Wiegand ◽  
Kelsey Schubach ◽  
...  

Abstract This experiment evaluated the impacts of bovine appeasing substance (BAS) administration on performance, health, and physiological responses of feedlot cattle during a 45-d receiving period. A total of 342 recently-weaned Angus-influenced steers, originating from 16 cow-calf operations, were obtained from an auction yard on d -1 and road-transported (12 h) to the feedlot. Upon arrival on d 0, body weight (BW) was recorded and steers were ranked by BW and source and assigned to receive BAS (Nutricorp, Araras, SP, Brazil; n = 171) or placebo (diethylene glycol monoethyl ether; CON; n = 171). Treatments (5 mL) were topically applied to the nuchal skin area of each animal. Within treatment, calves were allocated to 1 of 24 drylot pens (12 pens/treatment) and received a free choice total-mixed ration from d 1 to 45. Calves were assessed for bovine respiratory disease (BRD) signs and feed intake was recorded from each pen daily. Steer BW was again recorded on d 1, 7, 17, 31, and 45, whereas blood samples were collected from 5 steers/pen concurrently with each BW assessment. Average daily gain was greater (P = 0.05) in BAS vs. CON calves, although final BW did not differ (P = 0.36) between treatments. No treatment effects were detected for feed intake (P = 0.95), resulting in greater (P = 0.05) feed efficiency in BAS vs. CON steers. No treatment effects were detected (P ≥ 0.37) for plasma concentrations of haptoglobin, whereas plasma cortisol concentrations were greater (P = 0.05) in CON vs. BAS steers on d 7 (treatment × day; P = 0.07). Incidence of BRD was greater (P ≤ 0.05) in BAS vs. CON on d 6 to 10 and d 18 to 21 (treatment × day; P < 0.01), although overall BRD incidence did not differ (P = 0.24) between treatments. The number of antimicrobial treatments required per steer diagnosed with BRD symptoms to recover from sickness was greater (P = 0.04) in CON vs. BAS calves. No treatment differences were detected (P ≥ 0.41) for mortality incidence, or proportion of steers removed from the experiment due to extreme sickness. Results from this experiment indicate BAS administration upon feedlot entry improved average daily gain by enhancing feed efficiency. Administration of BAS facilitated earlier detection of BRD and reduced the need for antimicrobial treatments. Collectively, these results suggest BAS administration as a promising strategy to benefit performance and immunocompetence of feedlot receiving cattle.


2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 39-40
Author(s):  
Kendi Tjardes ◽  
Katy Lippolis

Abstract One hundred four Angus calves were ranked by gender, BW, age, and dam parity, and assigned to 1 of 4 pre-weaning treatments: 1) nose flaps for 7-d prior to weaning (NF), 2) traditional weaning (TRAD), 3) traditional weaning and creep feed for 3-wk prior to weaning (TRADC), or 4) nose flaps for 7-d prior to weaning and creep feed for 3-wk prior to weaning (NFC). Cow-calf pairs were housed in dry lot pens on d -28. From d -21 to 0, calves in creep treatments were provided free choice access to creep feed. Nose flaps were placed on d -7, and calves were weaned on d 0. Calves were vaccinated and dewormed on d -21 and 0. There was no difference (P ≥ 0.97) in calf BW on d -28 or -21. During the 7-d period that nose flaps were placed, NFC calves had greater (P ≤ 0.0001) ADG than NF and TRAD calves, and tended to have greater (P ≤ 0.10) ADG than TRADC calves. At weaning on d 0, TRADC and NFC calves tended to have greater BW (P = 0.07) and had greater overall change in BW (P < 0.0001) during the pre-weaning period than TRAD and NF calves. Additionally, there was a greater (P ≤ 0.001) increase in BW of NFC and TRADC cows during the pre-weaning period compared to NF and TRAD cows. From d -21 to 0 there was no differences (P > 0.41) in plasma concentrations for Bovine Viral Diarrhea Virus (BVD). By d 14, the TRADC calves had the greatest plasma concentrations for BVD (P < 0.04). Therefore, providing short-term creep feed prior to placing nose flaps can improve pre-weaning calf and cow performance compared to traditional and nose flap weaning without creep feed supplementation, however, did not improve response to vaccination.


2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 152-153
Author(s):  
Aubree M Beenken ◽  
Erin L Deters ◽  
Colten W Dornbach ◽  
Stephanie L Hansen ◽  
Joshua C McCann ◽  
...  

Abstract Ninety-one early-weaned (65 ± 11 d) Angus steers (92 ± 4 kg) were blocked by age to a 2 × 2 factorial examining effects of injectable vitamin C (VC) at weaning and/or prior to transport to the feedlot on antibody titers and growth performance. Injections (20 mL/steer) of VC (250 mg sodium ascorbate/mL) or saline (SAL) were given at time of weaning on d 0 (WEAN) and/or prior to a 6 hr trucking event to a feedlot on d 49 (TRANS). Steers were given booster vaccinations on d 0. Steers were weighed on d 0, 1, 14, 48, 49, 64, 106, and 107. Blood was collected (12 steers/treatment) on d 0, 1, 2, 14, 49 (pre- and post-transit), 50, and 51. Data were analyzed via Proc-Mixed of SAS (experimental unit = steer; n = 22–23/treatment) with fixed effects of block, WEAN, TRANS, and WEAN × TRANS. Plasma ascorbate concentrations for weaning (d 0, 1, and 2) and transit (d 49-pre-trucking, 49-post-trucking, 50, and 51) were analyzed as repeated measures (repeated effect = day). Plasma ascorbate concentrations were greater on d 1 and 2 for steers that received VC at weaning (VC = 19.6, SAL = 8.8 ± 1.26 µM; WEAN × day P < 0.01). Similarly, ascorbate concentrations were greater on d 49 post-trucking, 50, and 51 for steers that received VC pre-transit (TRANS × day P = 0.01). Treatments did not affect bodyweight or average daily gain throughout the trial (P > 0.32). There were no effects of treatment on serum Bovine Viral Diarrhea Virus type 2 antibody titers on d 14 or 51 (P > 0.33). An injection of VC administered to early weaned beef steers at weaning or pre-transit increases plasma ascorbate concentrations but does not improve growth performance or antibody response to vaccination booster.


2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 193-194
Author(s):  
Jacob Wiegand ◽  
Reinaldo F Cooke ◽  
Alice Brandão ◽  
Kelsey Schubach ◽  
Eduardo Colombo ◽  
...  

Abstract This experiment compared physiological, health, and performance responses of beef heifers assigned to different commingling schemes (1, 2, or 4 sources/pen) during a 56-d feedlot receiving period. Ninety-six recently weaned Angus-influenced heifers were purchased from a commercial auction facility. Heifers originated from 4 cow-calf ranches, and were reared in the same herd within each ranch since birth. Heifers were loaded by source into commercial livestock trailers at the auction yard, and transported for 8 h to stimulate the stress of a long haul. Heifers were not mixed with cohorts from other sources prior to and at the auction yard. Upon arrival at the receiving yard (d -2), shrunk body weight (BW) was recorded, and heifers were maintained in 4 paddocks by source with ad libitum access to hay, water, and a mineral supplement for 36 h. On d 0, heifers were ranked by source and shrunk BW and allocated to 1 of 24 drylot pens (4 heifers/pen) containing: 1) heifers from a single source (NOCOM, n = 8 pens), 2) heifers from 2 sources (COM2, n = 8 pens), or 3) heifers from 4 sources (COM4, n = 8 pens). From d 0 to 55, heifers had free-choice access to water and a total-mixed ration. Heifers were assessed for bovine respiratory disease (BRD) signs and feed intake was recorded from each pen daily. Blood samples were collected from all heifers on d 0, 6, 13, 27, 41, and 55, and shrunk BW (after 16 h of water and feed withdrawal) was collected on d 56 for average daily gain (ADG) calculation. Final shrunk BW and ADG did not differ (P ≥ 0.83) between NOCOM, COM2, and COM4 heifers (0.85, 0.88, and 0.82 kg/d of ADG, respectively, SEM = 0.08). No treatment effects were detected (P ≥ 0.77) for feed intake and feed efficiency, as well as plasma concentrations of haptoglobin and cortisol. No treatment differences were noted (P ≥ 0.49) for morbidity (53.1, 68.7, and 56.2% of NOCOM, COM2, and COM4 heifers diagnosed with BRD, respectively; SEM = 9.7) or mortality during the experiment. A similar (P ≥ 0.97) proportion of NOCOM, COM2, and COM4 heifers diagnosed with BRD required at least two treatments to recover from sickness. In turn, a third treatment was not required for NOCOM heifers, which was less compared with COM4 (P = 0.05) and similar (P = 0.23) compared with COM2 heifers. Perhaps the number of heifers assigned to commingled pens, and resultant pre-existing social groups, was not sufficient to stimulate the stress reactions caused by social destabilization.


2020 ◽  
Vol 4 (4) ◽  
Author(s):  
Jacob B Wiegand ◽  
Reinaldo F Cooke ◽  
Alice P Brandão ◽  
Kelsey M Schubach ◽  
Eduardo A Colombo ◽  
...  

Abstract This experiment compared physiological, health, and performance responses of beef heifers assigned to different commingling schemes (one, two, or four sources per pen) during a 56-d feedlot receiving period. Ninety-six recently weaned Angus-influenced heifers were obtained from an auction facility. Heifers originated from four cow-calf ranches, and were reared in the same herd within each ranch since birth. Heifers were loaded into two livestock trailers at the auction yard (two sources per trailer; d −2), arranged in two sections of each trailer according to source, and transported for 10 h to stimulate the stress of a long-haul. Heifers were not mixed with cohorts from other sources prior to and at the auction yard. Upon arrival (d −2), shrunk body weight (BW) was recorded and heifers were maintained in four paddocks by source with ad libitum access to a complete starter feed and water for 36 h. On d 0, heifers were ranked by source and shrunk BW and allocated to 1 of 24 drylot pens (four heifers per pen) containing: 1) heifers from a single source (1SRC, n = 8), 2) heifers from two sources (2SRC, n = 8), or 3) heifers from four sources (4SRC, n = 8). From d 0 to d 55, heifers had free-choice access to the complete starter feed and water. Heifers were assessed daily for symptoms of bovine respiratory disease (BRD), and feed intake was recorded from each pen daily. Blood samples were collected on d 0, d 6, d 13, d 27, d 41, and d 55, and shrunk BW (after 16 h of water and feed withdrawal) was recorded on d 56 for average daily gain (ADG). No treatment differences were noted (P ≥ 0.56) for heifer ADG (mean ± SE = 0.853 ± 0.043 kg/d), final shrunk BW, feed intake, and feed efficiency. No treatment differences were noted (P ≥ 0.27) for plasma concentrations of cortisol and haptoglobin, and serum concentrations of antibodies against BRD viruses and Mannheimia haemolytica. No treatment differences were noted (P ≥ 0.17) for incidence of BRD (mean ± SE = 59.3 ± 5.0%) or mortality. The proportion of heifers diagnosed with BRD that required three antimicrobial treatments to regain health increased linearly (P = 0.03) according to the number of sources (0.0, 12.3, and 20.8% of 1SRC, 2SRC, and 4SRC heifers, respectively; SEM = 7.0). Hence, commingling heifers from different sources did not impact performance, physiological responses, and BRD incidence during a 56-d receiving period, although recurrence of BRD after the second antimicrobial treatment increased according to commingling level.


Animals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1961
Author(s):  
Beatriz Angeli ◽  
Bruno Cappellozza ◽  
José Luiz Moraes Vasconcelos ◽  
Reinaldo Fernandes Cooke

(1) Background: Ruminants often face stressful situations throughout their productive lives. More specifically, pre-weaning dairy calves are exposed to novel environments, feedstuffs, and pathogens that affect their health and performance. Hence, alternatives that reduce stress and promote growth of pre-weaning dairy calves are warranted. Therefore, this study evaluated the effects of biweekly bovine appeasing substance (BAS) administration on performance and disease incidence in dairy Gir × Holstein female calves prior to weaning. (2) Methods: At birth, 140 female Gir × Holstein calves were randomly assigned to receive BAS (SecureCattle; (IRSEA Group, Quartier Salignan, France; n = 70) or placebo (BAS carrier, diethylene glycol monoethyl ether; CON; n = 70) biweekly until weaning (70 days of age). Calves were allocated into individual housing at random, with no physical contact between treatments to avoid cross-contamination. Experimental treatments (5 mL) were applied topically to the nuchal skin area of each calf. Throughout the experimental period, all animals were observed daily for medical conditions (diarrhea, pneumonia, and others), medical/pharmacological interventions were recorded, and the costs related to these procedures were analyzed. Concurrently with treatment application, calves were individually weighed, and data were analyzed using animal as the experimental unit. (3) Results: Treatment × day and treatment × period (14-day interval) interactions were observed for body weight (BW) and average daily gain (ADG; p ≤ 0.05), respectively. Calves receiving BAS had greater BW at weaning (p = 0.02) and tended to have a greater BW on day 56 (p = 0.06). Similarly, ADG was greater for BAS from days 42 to 56 (p = 0.04) and tended to be greater from days 56 to weaning (p = 0.10). No differences were observed on the overall occurrence of diseases (p = 0.92), whereas the most common observed diseases were diarrhea and pneumonia. The incidence and mean age at which animals were detected with these diseases did not differ (p ≥ 0.46). Nonetheless, CON calves detected with disease had a reduced ADG vs. BAS-administered counterparts (p < 0.01). No differences were observed between disease-diagnosed BAS vs. healthy CON, but healthy BAS had a greater ADG vs. healthy CON (p = 0.03). A treatment effect was observed for the cost per head of each pharmacological intervention (p = 0.05). (4) Conclusions: In summary, BAS administration at a 14-day interval improved performance and reduced the costs of pharmacological interventions of pre-weaning Gir × Holstein dairy calves.


2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 219-220
Author(s):  
Kendi Sayre ◽  
Katy Lippolis ◽  
Chris Clark

Abstract One hundred three Angus calves were ranked by gender, BW, age, and dam parity, and assigned to 1 of 4 pre-weaning treatments: 1) nose flaps for 7-d prior to weaning (NF), 2) traditional weaning (TRAD), 3) traditional weaning and creep feed for 3-wk prior to weaning (TRADC), or 4) nose flaps for 7-d prior to weaning and creep feed for 3-wk prior to weaning (NFC). Cow-calf pairs were housed in dry lot pens on d -28. From d -21 to 0, calves in creep treatments were provided free choice access to creep feed. Nose flaps were placed on d -7, and calves were weaned on d 0. Calves were vaccinated and dewormed on d -21 and 0. There was no difference (P ≥ 0.97) in calf BW on d -28 or -21. During the 7-d period that nose flaps were placed, NFC calves had greater (P ≤ 0.0001) ADG than NF and TRAD calves and tended to have greater (P ≤ 0.10) ADG than TRADC calves. At weaning on d 0, TRADC and NFC calves tended to have greater BW (P = 0.07) and had greater overall change in BW (P &lt; 0.0001) during the pre-weaning period than TRAD and NF calves. Additionally, there was a greater (P ≤ 0.001) increase in BW of NFC and TRADC cows during the pre-weaning period compared to NF and TRAD cows. From d -21 to 0 there was no differences (P &gt; 0.41) in plasma concentrations for Bovine Viral Diarrhea Virus (BVD). By d 14, the TRADC calves had the greatest plasma concentrations for BVD (P &lt; 0.04). Therefore, providing short-term creep feed prior to placing nose flaps can improve pre-weaning calf and cow performance compared to traditional and nose flap weaning without creep feed supplementation, however, did not impact response to vaccination.


2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 167-168
Author(s):  
Miles D Redden ◽  
Joshua C McCann ◽  
Daniel W Shike

Abstract The objective was to assess the effect of increasing metabolizable protein (MP) supply to lightweight beef steers on total tract digestion, N balance, and performance. The 2016 Beef Cattle Nutrient Requirements Model (BCNRM) prediction of MP requirements in lightweight beef steers (less than 250 kg) is limited by available data. Spring-born Angus steers (n = 12; BW = 166 +/- 10.7 kg) were weaned at 97 ± 10 d of age, backgrounded 42 d, implanted with Component TE-IS, stratified by BW, and assigned to one of four treatments in a crossover design with two 19 day periods. Each period included a 12-day adaptation followed by a 6-day collection period of total orts, feces, and urine. Treatment diets were formulated to provide 0.62 (MP1), 0.76 (MP2), 0.89 (MP3), and 1.01 (MP4) kg MP per day. Metabolizable energy was similar across diets (2.14 Mcal/kg). Data were analyzed using the Mixed procedure of SAS. Dry matter intake was not affected by treatment (P = 0.92) and averaged 5.7 kg per d. Average daily gain (ADG) tended (P = 0.06) to increase quadratically with MP provision with 1.45, 1.72, 1.93, and 1.71 kg per day for MP1, MP2 MP3, and MP4, respectively. Feed efficiency (G:F) also increased quadratically (P = 0.05) at 0.27, 0.32, 0.35, and 0.31 for MP1, MP2 MP3, and MP4, respectively. Greater dietary MP linearly increased (P &lt; 0.01) N intake, N absorption, and urinary N. Fecal N and retained N were not affected by treatment (P ≥ 0.56). Apparent organic matter digestibility increased linearly (P ≤ 0.01). Increasing MP resulted in a linear increase in N absorption but a quadratic response for ADG, suggesting MP greater than 0.89 kg per d may exceed MP requirements for steers weighing 166 kg and consuming a 2.14 Mcal/kg diet.


2020 ◽  
Vol 98 (11) ◽  
Author(s):  
Bruna Rett ◽  
Reinaldo F Cooke ◽  
Alice P Brandão ◽  
Vitor S M Ferreira ◽  
Eduardo A Colombo ◽  
...  

Abstract This experiment compared incidence of frothy bloat, as well as ruminal, physiological, and performance responses of beef heifers receiving a bloat-provoking diet and supplemented with Yucca schidigera extract. Sixteen ruminally cannulated Angus-influenced heifers were ranked by body weight (BW) and assigned to 4 groups of 4 heifers each. Groups were enrolled in a replicated 4 × 4 Latin square design containing 4 periods of 28 d, and a 21-d washout interval between periods. Groups were assigned to receive no Y. schidigera extract (CON), or Y. schidigera extract at (as-fed basis) 1 g/heifer daily (YS1), 2 g/heifer daily (YS2), or 4 g/heifer daily (YS4). During each period, heifers (n = 16/treatment) were housed in individual pens, and fed a sorghum (Sorghum bicolor L.)-based bloat-provocative diet at 2% of their BW. Diet and treatments were individually fed to heifers, twice daily in equal proportions (0700 and 1600 hours). Heifers were assessed for bloat score (0 to 5 scale, increasing according to bloat severity) 3 hr after the morning feeding. Blood samples were collected on days 0, 7, 14, 21, and 28 prior to (0 hr) and at 3, 6, and 9 hr relative to the morning feeding. Rumen fluid samples were collected at the same time points on days 0 and 28. Orthogonal contrasts were tested to determine whether inclusion of Y. schidigera extract (0, 1, 2, or 4 g/heifer daily) yielded linear or quadratic effects, and explore an overall effect of Y. schidigera extract supplementation (CON vs. YS1 + YS2 + YS4). Rumen fluid viscosity was impacted quadratically by Y. schidigera extract inclusion (P = 0.02), being greatest in YS1, followed by YS2, and equivalent between CON and YS4 heifers. Heifers receiving Y. schidigera extract had greater (P ≤ 0.05) rumen propionate, iso-valerate, and valerate concentrations, as well as less (P &lt; 0.01) acetate : propionate ratio compared with CON heifers. Inclusion of Y. schidigera extract linearly increased (P ≤ 0.04) average daily gain and feed efficiency. No other treatment effects were noted (P ≥ 0.19) including bloat score (1.07 ± 0.03 across treatments), ruminal protozoa count, plasma concentrations of cortisol, haptoglobin, urea N, total protein, and rumen concentration of total volatile fatty acids. Supplementing Y. schidigera extract up to 4 g/d favored rumen propionate concentrations and linearly increased growth and feed efficiency but failed to mitigate incidence of frothy bloat in beef heifers consuming a grain-based bloat-provocative diet.


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