Nutritional strategies to improve the reproductive performance of beef females

In the first set of studies, 2 experiments evaluated the influence of supplement composition on ruminal forage disappearance, performance, and physiological responses of Angus × Hereford cattle consuming a low-quality, cool-season forage (8.7 % CP and 57 % TDN). In Exp. 1, 6 rumen-fistulated steers housed in individual pens were assigned to an incomplete 3 x 2 Latin square design containing 2 periods of 11 d each and the following treatments: 1) supplementation with soybean meal (PROT), 2) supplementation with a mixture of cracked corn, soybean meal, and urea (68:22:10 ratio, DM basis; ENER), or 3) no supplementation (CON). Steers were offered meadow foxtail (Alopecurus pratensis L.) hay for ad libitum consumption. Treatments were provided daily at 0.50 and 0.54 % of shrunk BW/steer for PROT and ENER, respectively, to ensure that PROT and ENER intakes were isocaloric and isonitrogenous. No treatment effects were detected on rumen disappearance parameters of forage DM (P ≥ 0.33) and NDF (P ≥ 0.66). In Exp. 2, 35 pregnant heifers were ranked by initial BW on d -7 of the study, allocated into 12 feedlot pens (4 pens/treatment), and assigned to the same treatments and forage intake regimen as in Exp. 1 for 19 d. Treatments were fed once daily at 1.77 and 1.92 kg of DM/heifer for PROT and ENER, respectively, to achieve the same treatment intake as % of initial BW used in Exp. 1 (0.50 and 0.54 % for PROT and ENER, respectively). No treatment effects (P = 0.17) were detected on forage DMI. Total DMI was greater (P < 0.01) for PROT and ENER compared with CON, and similar between PROT and ENER (P = 0.36). Accordingly, ADG was greater (P = 0.01) for PROT compared with CON, tended to be greater for ENER compared with CON (P = 0.08), and was similar between ENER and PROT (P = 0.28). Heifers receiving PROT and ENER had greater mean concentrations of plasma glucose (P = 0.03), insulin (P ≤ 0.09), IGF-I (P ≤ 0.04), and progesterone (P₄; P = 0.01) compared to CON, whereas ENER and PROT had similar concentrations of these variables (P ≥ 0.15). A treatment × hour interaction was detected (P < 0.01) for plasma urea N (PUN), given that PUN concentrations increased after supplementation for ENER and PROT (time effect, P < 0.01), but did not change for CON (time effect; P = 0.62). In conclusion, beef cattle consuming low-quality cool-season forages had similar ruminal forage disappearance and intake, performance, and physiological status if offered supplements based on soybean meal or corn at approximately 0.5 % of BW (DM basis). The following experiment evaluated the influence of supplement composition on performance, reproductive, and metabolic responses of Angus × Hereford heifers consuming a low-quality cool-season forage (8.7 % CP and 57 % TDN). Sixty heifers (initial age = 226 ± 3 d) were allocated into 15 drylot pens (4 heifers/pen; 5 pens/treatment), and assigned to the same treatments as reported above. Heifers were offered meadow foxtail (Alopecurus pratensis L.) hay for ad libitum consumption during the experiment (d -10 to 160). Beginning on d 0, PROT and ENER were provided daily at a rate of 1.30 and 1.40 kg of DM/heifer to ensure that PROT and ENER intakes were isocaloric and isonitrogenous. Hay and total DMI were recorded for 5 consecutive days during each month of the experiment. Blood was collected every 10 d for analysis of plasma P₄ to evaluate puberty attainment. Blood samples collected on d -10, 60, 120, and 150 were also analyzed for PUN, glucose, insulin, IGF-I, NEFA, and leptin. Liver samples were collected on d 100 from 2 heifers/pen, and analyzed for mRNA expression of genes associated with nutritional metabolism. No treatment effect was detected (P = 0.33) on forage DMI. Total DMI, ADG, mean concentrations of glucose, insulin, and IGF-I, as well as hepatic mRNA expression of IGF-I and IGFBP-3 were greater (P ≤ 0.02) for PROT and ENER compared with CON, and similar between PROT and ENER (P ≥ 0.13). Mean PUN concentrations were also greater (P < 0.01) for PROT and ENER compared with CON, whereas PROT heifers had greater (P < 0.01) PUN compared with ENER. Plasma leptin concentrations were similar between ENER and PROT (P ≥ 0.19), and greater (P ≤ 0.03) for ENER and PROT compared with CON on d 120 and 150 (treatment × day interaction; P = 0.03). Hepatic mRNA expression of mitochondrial phosphoenolpyruvate carboxykinase was greater (P = 0.05) in PROT compared with CON and ENER, and similar between CON and ENER (P = 0.98). The proportion of heifers pubertal on d 160 was greater (P < 0.01) in ENER compared with PROT and CON, and similar between PROT and CON (P = 0.38). In conclusion, beef heifers consuming a low-quality cool-season forage had a similar increase in DMI, growth, and overall metabolic status if offered supplements based on soybean meal or corn at 0.5 % of BW. The last experiment was designed to determine if frequency of protein supplementation impacts physiological responses associated with reproduction in beef cows. Fourteen non-pregnant, non-lactating beef cows were ranked by age and BW, and allocated to 3 groups. Groups were assigned to a 3 × 3 Latin square design, containing 3 periods of 21 d and the following treatments: 1) soybean meal (SB) supplementation daily (D), 2) SB supplementation 3 times/wk (3WK), and 3) SB supplementation once/wk (1WK). Within each period, cows were assigned to an estrus synchronization protocol; 100 μg of GnRH + controlled internal drug release (CIDR) containing 1.38 g of P4 on d 1, 25 mg of PGF₂α on d 8, and CIDR removal + 100 μg of GnRH on d 11. Grassseed straw was offered for ad libitum consumption. Soybean meal was individually supplemented at a daily rate of 1 kg/cow (as-fed basis). Moreover, 3WK were supplemented on d 0, 2, 4, 7, 9, 11, 14, 16, and 18, whereas 1WK were supplemented on d 4, 11, and 18. Blood samples were collected from 0 (prior to) to 72 h after supplementation on d 11 and 18, and analyzed for PUN. Samples collected from 0 to 12 h were also analyzed for plasma glucose, insulin, and P4 (d 18 only). Uterine flushing fluid was collected concurrently with blood sampling at 28 h for pH evaluation. Liver biopsies were performed concurrently with blood sampling at 0, 4, and 28 h, and analyzed for mRNA expression of carbamoylphosphate synthetase I (CPS-I; h 28), and CYP2C19 and CYP3A4 (h 0 and 4 on d 18). Plasma urea-N concentrations were greater (P < 0.01) for 1WK vs. 3WK from 20 to 72 h, and greater (P < 0.01) for 1WK vs. D from 16 to 48 h and at 72 h after supplementation (treatment × hour interaction; P < 0.01). Moreover, PUN concentrations peaked at 28 h after supplementation for 3WK and 1WK (P < 0.01), and were greater (P < 0.01) at this time for 1WK vs. 3WK and D and for 3WK vs. D. Expression of CPS-I was greater (P < 0.01) for 1WK vs. D and 3WK. Uterine flushing pH tended (P ≤ 0.10) to be greater for 1WK vs. 3WK and D. No treatment effects were detected (P ≥ 0.15) on expression of CYP2C19 and CYP3A4, plasma glucose and P4 concentrations, whereas plasma insulin concentrations were greater (P ≤ 0.03) in D and 3WK vs. 1WK. Hence, decreasing frequency of protein supplementation did not reduce uterine flushing pH or plasma P₄ concentrations, which are known to impact reproduction in beef cows. In summary for all the experiments presented herein: (1) pregnant and developing replacement beef heifers consuming a low-quality, cool-season forage equally utilize and benefit, in terms of growth and metabolic parameters, from supplements based on protein or energy ingredients provided at approximately 0.5 % of heifer BW/d, (2) energetic supplementation at approximately 0.5 % BW/d did not impair forage disappearance parameters in rumen-fistulated steers, and (3) decreasing soybean meal supplementation frequency to once a week did not increase uterine pH, plasma P₄, and expression of hepatic enzymes associated with steroid catabolism in ruminants

Effects of supplementation of calcium salts of polyunsaturated fatty acids on serum concentrations of progesterone and insulin of pregnant dairy cows

Forty-five non-lactating, pregnant Holstein animals (18 heifers and 27 multiparous cows; BW = 561±114 kg; BCS = 2.9±0.3; days pregnant = 110±56 d) were stratified by initial BW and BCS, and randomly assigned to receive daily (as-fed basis) 0.50 kg of ground corn plus 0.22 kg of kaolin (CON), calcium salts of saturated fatty acids (SFA) or polyunsaturated fatty acids (PF) for 14 d. Blood samples were collected on days 0, 7 and 14, immediately prior to (0 h) and 3, 6, 9 and 12 h after feeding, to determine the serum concentrations of P₄ and insulin. No treatment effects were detected for serum concentrations of P₄ (5.52, 6.13 and 5.63±0.41 ng/mL for CON, SFA and PF, respectively). No treatment effects were detected for serum concentrations of insulin (11.5, 10.5 and 10.1±1.43 μIU/mL for CON, SFA and PF, respectively). Heifers had greater serum concentrations of P₄ than multiparous cows (6.35 vs. 5.16±0.42 ng/mL), but lower serum concentrations of insulin (7.0 vs. 14.4±1.49 μIU/mL). Feeding 0.22 kg of calcium salts of polyunsaturated fatty acids is not sufficient to increase the serum concentrations of P₄ and insulin of non-lactating, pregnant dairy cows.Keywords: Hepatic metabolism, Linoleic, Linoleni

Effects of camelina meal supplementation on ruminal forage degradability, performance, and physiological responses of beef cattle

Three experiments compared ruminal, physiological, and performance responses of beef steers consuming hay ad libitum and receiving grain-based supplements with (CAM) or without (CO) inclusion of camelina meal. In Exp. 1, 9 steers fitted with ruminal cannulas received CAM (2.04 kg of DM/d) or CO (2.20 kg of DM/d). Steers receiving CAM had reduced (P = 0.01) total DMI and tended to have reduced (P = 0.10) forage DMI compared to CO. No treatment effects were detected (P ≥ 0.35) for ruminal hay degradability parameters. In Exp. 2, 14 steers receiving CAM (1.52 kg of DM/d) or CO (1.65 kg of DM/d) were assigned to corticotropin-releasing hormone (CRH; 0.1 μg/kg of BW) and thyrotropin-releasing hormone (TRH; 0.33 μg/kg of BW) challenges. Steers receiving CAM had greater (P < 0.05) serum concentrations of PUFA compared to CO prior to challenges. Upon CRH infusion, mean plasma ceruloplasmin concentrations increased at a lesser rate in CAM compared with CO (P < 0.01). Upon TRH infusion, no treatment effects were detected (P ≥ 0.55) for serum TSH, T₃, and T₄. In Exp. 3, 60 steers were allocated to 20 drylot pens. Pens were randomly assigned to receive CAM (2.04 kg of DM/steer daily) or CO (2.20 kg of DM/steer daily) during preconditioning (PC; d -28 to 0). On the morning of d 0, steers were transported for 24 h. Upon arrival from transport on d 1, pens were randomly assigned to receive, in a 2 x 2 factorial arrangement, CAM or CO during feedlot receiving (FR; d 1 to 29). During PC, CAM had reduced (P < 0.01) forage and total DMI, and tended to have reduced (P = 0.10) ADG compared to CO. Plasma linolenic acid concentrations increased during PC for CAM, but not for CO (P = 0.02). Steers that received CAM during FR had greater (P < 0.05) mean plasma concentrations of PUFA, and reduced mean rectal temperature and concentrations of haptoglobin and ceruloplasmin during FR compared to CO. Therefore, camelina supplementation reduced forage and total DMI, did not alter thyroid gland function, increased PUFA concentrations in blood, and attenuated the acute-phase protein reaction elicited by neuroendocrine stress responses. In conclusion, camelina meal is a feasible ingredient to reduce stress-induced inflammatory reactions and potentially promote cattle welfare and productivity in beef operations

Omega-6 Fatty Acids: A Sustainable Alternative to Improve Beef Production Efficiency

Global beef production must increase in the next decades to meet the demands of a growing population, while promoting sustainable use of limited natural resources. Supplementing beef cattle with omega-6 fatty acids (FAs) is a nutritional approach shown to enhance production efficiency, with research conducted across different environments and sectors of the beef industry. Omega-6 FA from natural feed ingredients such as soybean oil are highly susceptible to ruminal biohydrogenation. Hence, our and other research groups have used soybean oil in the form of Ca soaps (CSSO) to lessen ruminal biohydrogenation, and maximize delivery of omega-6 FA to the duodenum for absorption. In cow–calf systems, omega-6 FA supplementation to beef cows improved pregnancy success by promoting the establishment of early pregnancy. Cows receiving omega-6 FA during late gestation gave birth to calves that were healthier and more efficient in the feedlot, suggesting the potential role of omega-6 FA on developmental programming. Supplementing omega-6 FA to young cattle also elicited programming effects toward improved adipogenesis and carcass quality, and improved calf immunocompetence upon a stress stimulus. Cattle supplemented with omega-6 FA during growing or finishing periods also experienced improved performance and carcass quality. All these research results were generated using cattle of different genetic composition (Bos taurus and B. indicus influenced), and in different environments (tropical, subtropical, and temperate region). Hence, supplementing omega-6 FA via CSSO is a sustainable approach to enhance the production efficiency of beef industries across different areas of the world

Different profiles of fatty acids in Ca soaps on dissociation and modification by biohydrogenation in vitro

This study evaluated the effects of rumen pH on in vitro Ca dissociation of different sources of Ca soaps of fatty acids (CSFA). Treatments were distributed in a 6×4 factorial design and consisted of six CSFA sources and four rumen fluid pH. The CSFA sources were: two sources of palm oil (PO1 and PO2), soybean oil (SO), palm + soybean oil (PSO), palm + cottonseed oil (PCO), and palm + cottonseed + soybean oil (PCSO). All CSFA samples were added to a pool of rumen fluid and adjusted to four different pH (5.5, 6.0, 6.5, and 7.0), and then, incubated at 37 ℃ for 1 h. This procedure was replicated over three consecutive days. Effect of CSFA source × rumen pH was detected for in vitro relative Ca dissociation and change (Δ) in concentrations of oleic, linoleic, and linolenic acids. Calcium dissociation did not differ among CSFA sources in pH 7.0 or 6.5, but was greater for SO vs. PO2, PSO, PCO, and PCSO in pH 6.0. Relative Ca dissociation in pH 5.5 was lower for PO1 and PSO vs. SO, but greater for PO1 and PSO vs. PCO and PCSO. The Δ of oleic acid was greater for PO2 vs. PCO in pH 6.5 and PO1 and PCSO vs. PO2 and SO in pH 7.0. The Δ of linoleic acid was greatest for SO across all pH evaluated and did not differ between PO1 and PO2, but both had a reduced Δ of linoleic acid than other CSFA sources in pH 5.5 and 7.0. The Δ of linolenic acid concentrations did not differ between PO1 and PO2, but both had less Δ of linolenic acid concentrations than other CSFA sources across all pH. Besides, SO had greater Δ of linolenic acid compared with PSO, PCO, and PCSO in pH 5.5, 6.0, and 6.5. Combining palm + cottonseed oil and palm + cottonseed + soybean oil reduces Ca dissociation and maintains the original fatty acid profile of the CSFA sourc

The Effect of Direct-Fed Microbials on In-Vitro Rumen Fermentation of Grass or Maize Silage

Direct-fed microbial products (DFM) are probiotics that can be used advantageously in ruminant production. The in vitro gas production technique (IVGPT) is a method to simulate rumen fermentation and can be used to measure degradation, gas production, and products of fermentation of such additives. However, inter-laboratory differences have been reported. Therefore, tests using the same material were used to validate laboratory reproducibility. The objective of this study was to assess the effect of adding two DFM formulations on fermentation kinetics, methane (CH4) production, and feed degradation in two different basal feeds while validating a newly established IVGPT laboratory. Six treatments, with three replicates each, were tested simultaneously at the established IVGPT lab at the University of Copenhagen, and the new IVGPT lab at Chr. Hansen Laboratories. Maize silage (MS) and grass silage (GS) were fermented with and without the following DFM: P1: Ligilactobacillus animalis and Propionibacterium freudenreichii (total 1.5 × 107 CFU/mL), P2: P1 with added Bacillus subtilis and B. licheniformis (total 5.9 × 107 CFU/mL). The DFM were anaerobically incubated in rumen fluid and buffer with freeze-dried silage samples for 48 h. Total gas production (TGP: mL at Standard Temperature and Pressure/gram of organic matter), pH, organic matter degradability (dOM), CH4concentration (MC) and yield (MY), and volatile fatty acid (VFA) production and profiles were measured after fermentation. No significant differences between the laboratories were detected for any response variables. The dOM of MS (78.3%) was significantly less than GS (81.4%), regardless of the DFM added (P1 and P2). There were no significant differences between the effects of the DFM within the feed type. MS produced significantly more gas than GS after 48 h, but GS with DFM produced significantly more gas at 3 and 9 h and a similar gas volume at 12 h. Both DFM increased TGP significantly in GS at 48 h. There was no difference in total VFA production. However, GS with and without probiotics produced significantly more propionic acid and less butyric acid than MS with and without probiotics. Adding P2 numerically reduced the total methane yield by 4–6% in both MS and GS. The fermentation duration of 48 h, used to determine maximum potential dOM, may give misleading results. This study showed that it is possible to standardize the methodology to achieve reproducibility of IVGPT results. Furthermore, the results suggest that the P2 DFM may have the potential to reduce CH4 production without affecting organic matter degradation

Microbiologic characterization of equine mastitis

Mastitis occurrence in mares is low if compared to other livestock species. The microorganisms often isolated and detected in milk and mammary gland secretions of mares are Streptococcus beta-haemolytica, Staphylococcus spp., Pseudomonas aeruginosa, Actinobacillus spp., and enterobacter. The present experiment was designed to evaluate the main microorganisms present in the milk of healthy mares and having a mammary infection. One hundred and ten mammary glands from 55 lactating mares were analyzed, ranging from 15 to 150 d post-partum. The mastitis diagnostic was performed through analysis of the milk via the screened test of the mug with dark background (Tamis), mammary gland inflammation and/or systemic signs. The subclinical mammary gland infection was characterized via the California Mastitis Test (CMT). From the 55 lactating mares, 2 (3.64%) had clinical mastitis. Following the CMT, the mares presented: 13 (23.60%), 7 (12.72%), and 12 (21.88%) scores from 1+, 2+, and 3+, respectively. From the 110 mamary glands were analysed, in 47 (85.45%) of these samples strains of microorganisms were isolated. In summary, results from our experiment suggest a low occurrence of clinical mastitis in lactating mares

Effects of supplementation of calcium salts of polyunsaturated fatty acids on serum concentrations of progesterone and insulin of pregnant dairy cows

Forty-five non-lactating, pregnant Holstein animals (18 heifers and 27 multiparous cows; BW = 561±114 kg; BCS = 2.9±0.3; days pregnant = 110±56 d) were stratified by initial BW and BCS, and randomly assigned to receive daily (as-fed basis) 0.50 kg of ground corn plus 0.22 kg of kaolin (CON), calcium salts of saturated fatty acids (SFA) or polyunsaturated fatty acids (PF) for 14 d. Blood samples were collected on days 0, 7 and 14, immediately prior to (0 h) and 3, 6, 9 and 12 h after feeding, to determine the serum concentrations of P4 and insulin. No treatment effects were detected for serum concentrations of P4 (5.52, 6.13 and 5.63±0.41 ng/mL for CON, SFA and PF, respectively). No treatment effects were detected for serum concentrations of insulin (11.5, 10.5 and 10.1±1.43 µIU/mL for CON, SFA and PF, respectively). Heifers had greater serum concentrations of P4 than multiparous cows (6.35 vs. 5.16±0.42 ng/mL), but lower serum concentrations of insulin (7.0 vs. 14.4±1.49 µIU/mL). Feeding 0.22 kg of calcium salts of polyunsaturated fatty acids is not sufficient to increase the serum concentrations of P4 and insulin of non-lactating, pregnant dairy cows