Ruminants, Volume 3, Issue 4 (December 2023) – 15 articles

The effectiveness of feed additives delivered through free-choice mineral mixtures (MMs) to grazing cattle remains unclear. Two farm-scale and one in vitro experiment (Exp.) were conducted to investigate the effects of salinomycin and virginiamycin, delivered through an MM, on growing bulls grazing tropical pastures. In Exp. 1, 316 zebu (Bos indicus) Nellore bulls (225 ± 26.7 kg liveweight (LW)) were randomly allocated to four treatments: (1) MM no additives (CON), (2) MM with salinomycin at 1950 mg/kg (SLI), (3) MM with salinomycin at 780 mg/kg (SHI), and (4) MM with virginiamycin at 1950 mg/kg (VGN). Over 123 days, these bulls grazed tropical grasses on pastures of guinea grass, palisade grass, or Bermuda grass. No significant treatment effects were observed for oocyst eggs or ruminal parameters. Bulls fed VGN had higher average daily gain (ADG) compared to CON (p = 0.02) and SLI (p = 0.03) but similar compared to SHI (p = 0.07). In Exp. 2, 308 zebu cross bulls (237 ± 23.0 kg LW) grazed Bermuda grass paddocks and were allocated into two treatments: (1) MM with no additives (CON) and (2) MM containing virginiamycin at 2522 mg/kg (VGN). Cattle fed VGN had a significantly higher ADG (p = 0.007). Exp. 3 tested salinomycin’s effectiveness in vitro at different exposure times to MM, revealing no impact of exposure time on short-chain fatty acid production. In conclusion, virginiamycin delivered through free-choice MM can increase grazing beef bulls’ ADG by 12% compared with CON, with no clear link to rumen fermentation or coccidiostat effects. Full article

Fostering orphan lambs is common in the United Kingdom and therefore it is important to understand more about these practices to support sustainable sheep farming. Data were collected on current approaches to adopting lambs and the perceived success of these methods using an online survey. Of the 543 responses, 93.7% reported that they attempt to foster lambs with the most common reasons reported as high litter size and ewes with little to no milk production. Although respondents reported that the best method was wet, non-tethering techniques, the most commonly used methods were tethered (restraint of the ewe) followed by untethered (birth fluids and skins from dead lambs). Other techniques included disguising the smell of the lamb. There was a significant association between increased flock size and using tethered methods as well as increased numbers of methods used and orphan lambs (p ≤ 0.001). However, larger flocks were also associated with decreased lamb survival rates (p ≤ 0.001). Time and patience were mentioned as important tips for fostering and could be a factor in which method is chosen. Research on the impacts of these methods is warranted as some may be stressful, affecting long-term flock performance, survival, welfare and health. Full article

The objective of this paper is to evaluate the effects of creep feeding supplementation during the preweaning phase on the growth performance and metabolic characteristics of Nellore heifers. Forty-two female Nellore calves (age = 100 ± 25 d; initial body weight (BW) = 113.4 ± 16.6 kg) were randomly assigned to the following treatments: control, where calves received mineral mix supplementation (n = 21); supplemented in creep feeding, where calves received 6 g/kg BW of a concentrate supplement (n = 21) during a period of 140 d. In the postweaning phase, all heifers received 6 g/kg BW of a concentrate supplement during a period of 210 d. Supplemented heifers had a greater average daily gain (ADG) than control heifers during the preweaning phase and, consequently, were heavier at weaning and at the end of the growing phase (p < 0.05). However, preweaning supplementation did not influence (p > 0.05) the body measurements or BW at the end of the growing period. Greater (p < 0.05) rib fat was observed in supplemented heifers. Concentrations of metabolites were not affected by preweaning supplementation (p > 0.05). Thus, supplementing heifers in the preweaning phase improved growth performance of weaning and body adiposity. Full article

We investigated the effects of short-term glycerin supplementation on follicular dynamics and pregnancy rates. Twenty-five goats with synchronized estrus and follicular waves with three injections of a prostaglandin analog every 7 days were used. Two days after the second injection, 13 goats were randomly chosen to receive an oral drench of 200 mL of glycerin (glycerin group [GG], n = 13) for 6 days, whereas the remaining 12 animals received an oral drench of saline (control group [CG], n = 12). At 24 and 48 h after the third injection, the goats mated. The animals were kept in a collective stall and received the same diet. The GG had higher blood glucose levels during the supplementation period than the CG (76.4 ± 1.9 vs. 50.3 ± 0.7 mg/dL; p < 0.01). The glycemic peak was recorded 4 h after the glycerin administration (102.3 ± 5.1 mg/dL) and remained higher than that in the CG 8 and 12 h later. The GG goats had a higher rectal temperature, heart rate, and respiratory rate than the CG goats and showed an increase in these parameters 4, 8, and 12 h after glycerin drenching. The GG animals also exhibited increased stress, urination, and drinking behaviors and reduced rumination. The ultrasonographic analysis showed a higher number of follicles with a diameter >4 mm (p < 0.05) and a greater follicular diameter (p < 0.01) in the waves before and after ovulation induction. The pregnancy and twinning rates and litter size at parturition were not different between the groups. Short-term supplementation with glycerin positively affects ovarian stimulation but has no effect on the reproductive response after mating. Full article

This review aimed to analyze the effects of additives in producing silage from rehydrated corn grains for ruminants. The control treatment studies used in this analysis involved corn grain rehydrated with water only. To be included in the review, the studies needed to follow standardized criteria, including the absence of additives in the control treatment and the silage evaluation of the in animals such as cattle, goats, and sheep. A total of fifteen publications between 2014 and 2023 were included in the final dataset. The PROC ANOVA of SAS was used to compare the results, which included a random effect of comparison within the study, performing a paired comparison. It was observed that additives did not influence the chemical composition, pH, organic acid, ethanol content, microbial population, fermentative losses, aerobic stability, and dry matter in vitro digestibility of rehydrated corn grain silage (p > 0.05). Using additives in corn silage is a promising practice that can significantly benefit silage fermentation. Moisture silage additives mitigate high mycotoxin levels, enhance aerobic stability, improve cell wall digestibility, and increase the efficiency of utilization of silage nitrogen by ruminants. Using fermentation-stimulating additives (Lactobacillus buchneri) can improve the quality of rehydrated corn grain silage. There are still a few studies and more research to elucidate the best additives and the ideal amount to be added to ground corn grain silage. Full article

Tannins can be utilized to increase rumen undegradable protein (RUP) by their capacity to form complexes with diverse nutrients present in the feed. In that regard, high-performance ruminants demand elevated RUP levels. The objective of this study was to evaluate the effects of incorporating varying levels of tannin into three protein sources (cottonseed, peanut, and soybean meals) on ruminal kinetic parameters, ruminal fermentation, and intestinal digestibility. Thus, three in situ experiments were conducted to investigate the ruminal degradation kinetics, where Fraction A represents the soluble portion, Fraction B relates to the portion potentially degraded in the rumen, and kd denotes the degradation rate of Fraction B, for both dry matter (DM) and crude protein (CP) in the rumen. Additionally, the study assessed dry matter effective degradability (ED), rumen undegradable protein (RUP), and intestinal digestibility (ID). These experiments utilized three cannulated animals for the in situ incubations. Regarding cottonseed meal in terms of DM degradation kinetics, tannin inclusion had a quadratic effect on fraction A (p < 0.01), B (p = 0.10, trend), kd (p = 0.03), and ED (p < 0.01). Fraction A of CP had a cubic effect (p = 0.03), being greater for the control compared with the other treatments. The inclusion of tannin linearly increased RUP (p < 0.01). The RUP proportion increased 29, 33, and 45% when 20, 40, and 60 g/kg tannin were used, respectively, compared to the control. For peanut meal, the A fraction of protein and RUP responded quadratically as tannin was included in peanut meal (p < 0.01). However, tannin levels did not affect fraction B of protein and ID. Regarding soybean meal, fractions A and B of DM and ED had cubic effects (p < 0.01), being greater for the control compared with the other treatments, and responded quadratically as tannin increased. Also, tannin inclusion had a cubic effect on fractions A and B of protein, RUP, and ID (p < 0.01). The cubic behavior showed greater B fraction and ID and lower A fraction and RUP for the control compared other treatments (p < 0.01). Tannins offer a promising avenue for elevating RUP levels in diets featuring cottonseed and peanut meals. Nevertheless, no advantages were observed when treating soybean meal with tannin. Full article

The influence of four levels of dietary supplementation on the development of the immune response and on the biology of Haemonchus contortus and Trichostrongylus colubriformis was evaluated in Dorper lambs under serial artificial infections with 1000 infective larvae (L3) of each species; the supplement was given every 3 days for 12 weeks. For each of the four diets formulated, one infected group (n = 7) and one control group (n = 4) were set up. Diets 1, 2, 3, and 4 contained 0%, 25%, 50%, and 75% of concentrate, respectively. There was an evident immune response to infection in all groups, manifested through eosinophilia and the production of anti-L3 immunoglobulins. There was a significant inverse relationship between the levels of nutrients in the diets and the numbers of late fourth-stage larvae, immature adult stages, and adults of H. contortus. Following 12 weeks of serial infections, most of the H. contortus population was found at the early fourth stage, indicating the occurrence of hypobiosis. The early fourth stage represented 59.5%, 75.8%, 83.3%, and 86.3% of the total Haemonchus worm burden, respectively, in Diets 1, 2, 3, and 4. In the case of T. colubriformis, hypobiosis was not observed, and diet had no influence on the establishment of parasites. Full article

Selecting high-immune-responding cattle benefits the individual animal and the herd. To assess factors that have a role in determining the immune status of cattle, this study used 55 weaned bull and 57 weaned heifer Brahman calves. Antibody-mediated immune response (AMIR) was determined by using a vaccine-specific IgG, enzyme-linked immunosorbent assay (ELISA) in response to cattle receiving the Salmonella Newport Extract vaccine. Cell-mediated immune response (CMIR) was determined by using a subcutaneous (neck) sensitization dose of Candida albicans (CA) with Quil-A adjuvant on Day 0. On Day 14, caudal skinfold thickness (SFT) was measured using Harpenden calipers prior to the intradermal injection of CA into the skinfold, and on Day 15, the injection site SFT was measured again. The response was determined by using the difference in SFT from Day 15 (post-injection) and Day 14 (pre-injection). In weaned Brahman calves, AMIR was not influenced by sex; however, there was sexual dimorphism associated with CMIR, in that bull calves had a greater response than heifers (p < 0.05). Our studies demonstrate that weaned Brahman calves can be separated into AMIR and CMIR classes and that AMIR and CMIR should be investigated further as selection tools in beef cattle production. Full article

The growing interest in improving rumen fermentation and mitigating methane emissions necessitates the use of essential oil blends (EOB) and fumaric acid (FA). This study evaluated the synergistic effect of four EOB with or without FA supplementation on in vitro dry matter digestibility, greenhouse gas emission, and total volatile fatty acid production using inoculum from three rumen-cannulated Black Angus beef cows. The study was arranged in a 4 × 2 + 1 factorial design to evaluate the effects of the four EOB and two FA levels on a total mixed ration (TMR). The EOB dosage was 100 µL while FA was added at 3% of total mixed ration. The EOB × FA interaction (p < 0.05) influenced the dry matter, neutral detergent fiber, and hemicellulose degradabilities. All the EOB and FA (EFA) treatments decreased (p < 0.001) the dry matter degradability compared to the control (TMR substrate only). The EFA4 treatment reduced the neutral detergent fiber and hemicellulose degradabilities compared to the control. The ruminal pH was influenced (p < 0.001) by both the EOB and FA inclusion, and the EOB × FA interaction was significant. The microbial mass was higher (p < 0.001) in the EFA1, EFA4, and EOB4 compared to the control and the EOB3 treatments. The EFA1 and EOB1 produced less (p < 0.001) gas than the control by 29.1 and 32.1%, respectively. Compared with the control, the EFA1 and EOB1 treatments decreased (p < 0.001) methane gas by 90.8% and 86.4%, respectively, while the carbon dioxide was reduced (p = 0.004) by 65.7 and 57.9%, respectively. The EOB × FA interaction was significant (p < 0.001) for the total and individual volatile fatty acid concentrations. The inclusion of FA increased the propionate concentration by 9.5% and decreased (p = 0.02) the acetate concentration by 4%. In summary, the synergistic effect of the EOB and FA offers an effective way to reduce greenhouse gas emission and enhance total volatile fatty acids. Full article

The objective of the current study was to compare the rumen inoculum of slaughtered cattle with the ruminal inoculum of cannulated cattle; additionally, determine its reliability in the in vitro analysis of ruminant feeds throughout a multivariate approach. Five male bovines (weight 320 ± 9.4 kg; mean ± standard deviation) provided with ruminal cannula and between five and seven bovines slaughtered in slaughterhouse were used. The evaluations were carried out following a completely randomized design. The data obtained were subjected to different multivariate analyzes to determine the reliability of the ruminal inoculum of animals slaughtered in commercial slaughterhouses compared to that obtained from cannulated animals. The relative contribution indicated that the in vitro dry matter digestibility (IVDMD, 50.75%) and in vitro neutral detergent fiber digestibility (IVNDFD, 29.83%) analysis influence 80.13% of the results to determine the reliability of the ruminal inoculum from slaughtered cattle. Furthermore, it was determined that the first two principal components (IVNDFD and acetic acid production) are the ones that influence the results by 89.87%. The grouping of diets using the Tocher optimization method and the dendrogram shows the formation of six groups and two groups, respectively. The grouping shows that the ruminal inoculum source was not the limiting parameter in the evaluation. Rumen inoculum from cattle slaughtered in a commercial slaughterhouse (with unknown diet) has potential as an alternative for the in vitro analysis of cattle feed, provided that the lignin concentration in the diet is less than 35.5 g/kg DM. Full article

This study aimed to identify behavioral and morphological traits of Nellore cattle that can influence calves’ survival and pre-weaning performance. It was performed in two units of a large-scale cow–calf operation farm located in the Central-West region of Brazil, with 975 cow–calf dyads, by scoring cows’ maternal protective behavior, body condition, horns, udder suspension (US), teat size (TS) and calves’ vigor. TS was used to determine teat symmetry (TSm). The production unit where calves were born, their birth date, sex, and birth (BW) and weaning weights were also recorded. Cow ages at calving and production units were used to categorize the cows into twelve classes (Cage). The Shapiro–Wilk test alongside tables of frequencies were used to determine if continuous and categorical variables followed a normal distribution, respectively. Two datasets were considered in statistical analyses: (i) 975 dyad records were used to identify potential factors influencing calf survivability and (ii) 936 records of weaned calves were used to assess pre-weaning performance. Generalized linear models were used to assess the effect of target traits on the calves’ weight adjusted for 210 days of age (W210, kg) and pre-weaning average daily gain (preADG, kg/day). Tukey’s test was used to compare W210 and preADG means. Pearson’s correlation coefficients were estimated between BW, W210 and preADG. Cage, US and the TSm significantly affected pre-weaning calf performance (p < 0.01). Older cows (independently of the production unit) and those with intermediate US and symmetrical teats weaned heavier calves. As expected, positive and significant correlation was observed between BW and preADG (r = 0.35), which, in turn, was highly correlated with W210 (r = 0.99). We concluded that none of the behavioral and morphological traits influenced calf survivability, but cow age, US and TSm impacted pre-weaning performance, with 8- to 11-year-old cows and those with intermediate US and symmetric teats leading to better calf performance at weaning. Full article

Probiotics are live microorganisms that promote host health through microbiota balance and immune modulation. We assessed an acidogenic bacterial consortium (ABC) with promising probiotic properties, focusing on its resilience during transit through the digestive tract in ruminants and determining its optimal in vitro dosage. The ABC exhibited antibiotic resistance, thrived at pH levels between 5 and 7 for 24 and 48 h, and showed a 77% survival rate in artificial gastric juice. Moreover, it not only endured bile salt exposure but also multiplied. The ABC exhibited 10.74% of coaggregation capabilities against E. coli. Optimal dosage determination revealed that 4 × 10⁸ was the ideal concentration, as higher doses did not yield significant differences in dry matter digestion. In the in vivo trial with Limousin Heifers, the ABC led to enhanced total volatile fatty acid (VFA) production, increased daily weight gains, and improved feed conversion rates compared to the control group. These findings underscore the potential of the ABC as a probiotic to boost animal productivity and overall health. Full article

Foot-and-mouth disease (FMD) is endemic in Iran and associated with a large impact on the livestock industry. Livestock mobility is recognized as one of the most important risk factors for FMD and other infectious livestock diseases’ introduction and dissemination. The description of temporal and spatial aspects of livestock mobility networks in Iran provides insights into FMD epidemiology. It also assists in the formulation of recommendations to mitigate the risk of animal disease transmission through livestock movements. This study is the first spatiotemporal description of official/registered cattle, sheep, goat, and camel movements in Iran, using records related to the period from March 2020 to August 2021 extracted from the Iran Veterinary Organization (IVO) Quarantine system. It shows that the static networks drawn by the movements of small ruminants, cattle, and camels to farms or slaughterhouses are complex and highlights the predominance of a few provinces and towns. In particular, the results show that Razavi Khorasan and West Azerbaijan provinces, major provinces for the Iranian livestock sector, are provinces where significant volumes of small ruminants and cattle are moved (from, to, or within) and, therefore, should be prioritized for targeted and timely risk reduction interventions. This study produces some of the necessary inputs for the risk assessment of FMD and similar transboundary animal diseases (TADs) spread within Iran, which is needed to regularly update the national risk-based control strategy for FMD and other TADs. Full article

We evaluated the effects of feeding 60% dried corn distillers’ grains plus solubles (DDGS) or the equivalent sulfur as CaSO₄ on sperm characteristics and transcript abundance. Thirty-six half-sibling Angus bulls (256 ± 8.5 d; initial BW = 320 ± 2.7 kg) were assigned to one of three treatments: (1) 60% concentrate as corn (CON); (2) 60% DDGS as corn replacement (60DDGS); and (3) CON diet + equivalent sulfur of 60DDGS added as CaSO₄ (SULF). The acrosome/cell membrane integrity, mitochondrial energy potential, oxidation status, DNA integrity, and zinc signatures were analyzed via flow cytometry. Sperm-specific gene expression was assessed via RNA sequencing. The flow cytometry data were analyzed using PROC MIXED in SAS to determine the effects of treatment. Pairwise comparisons based on edgeR were used to identify differentially expressed genes. The percentage of polarized mitochondria tended to be greater (p = 0.08) for SULF compared with CON and 60DDGS. Protamine 1 was upregulated (p < 0.01; FDR = 0.10) in 60DDGS compared to CON. Zinc signature 1 in 60DDGS and SULF was reduced (p = 0.03) compared to CON. This study suggests that feeding bulls diets containing 60% DDGS had little effect on DNA integrity and gene expression. Full article

Automatic calf feeders (AMFs) that supply milk for pre-weaning calves require group housing. This observational study assessed calf growth, health, feeding patterns and social behaviours prior to, during and following weaning in groups on the AMF. Calves were recruited from a single UK dairy farm and placed into two groups on the AMF between 3 and5 weeks of age (n = 19 and 13). They were fed milk near-ad libitum until 8 weeks of age when they entered a 2-week step-down weaning period. Daily milk consumption and the numbers of successful and refusal visits were collected from the AMF, along with weekly weights and health checks. Calf behaviour around the AMF was monitored through video analysis, and activity was assessed using tri-axial accelerometers. On average, the calves consumed approximately 3 L of milk three times a day from the AMF, confirming that limiting calves to twice daily feeding will restrict their desired milk consumption. The ADLG pre-weaning was 0.74 kg/d (SD 0.41 kg), rising to 0.99 kg/d (SD 0.46 kg) over weaning and 1.05 kg/d (SD 0.12 kg) post weaning. Refusal visits to the AMF, social interactions, displacements and cross sucking all increased over the weaning periods, suggesting that the calves were experiencing frustration due to a lack of expected milk rewards rather than hunger as ADLG continued to increase. Female calves also had more successful and refusal visits to the AMF than males, along with higher displacement indexes (p = 0.052), suggesting single-sex groups may be beneficial to AMFs. Calf activity had a diurnal pattern, with the highest standing times being during mid-morning and early evening, which may put pressure on limited resources if all calves are active during these particular time periods. Full article