Intact Rams Research Articles

Integrative Meta-Analysis: Unveiling Genetic Factors in Meat Sheep Growth and Muscular Development through QTL and Transcriptome Studies.

The study aimed to investigate the effects of castration on performance, carcass characteristics, and meat quality in sheep, as well as explore the expression of key genes related to metabolic pathways and muscle growth following castration. A meta-analysis approach was utilized to analyze data from multiple studies to compare the performance, carcass characteristics, and meat quality of castrated sheep (wethers) with intact rams. Additionally, protein-protein interaction (PPI) networks, differential gene expression (DEG) interactions, Gene Ontology (GO) terms, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were examined to identify molecular mechanisms associated with fat metabolism and muscle development in sheep tails. The analysis revealed that castrated sheep (wethers) exhibited improved average daily gain, increased tenderness, lower backfat thickness, and a tendency for greater loin muscle area compared to intact rams. This suggests that castration promotes faster growth and results in leaner carcasses with potentially higher muscle content. Furthermore, the identification of downregulated DEGs like ACLY, SLC27A2, and COL1A1 and upregulated DEGs such as HOXA9, PGM2L1, and ABAT provides insights into the molecular mechanisms underlying fat deposition and muscle development in sheep. The findings support the practice of castration in sheep production as it enhances growth performance, leads to leaner carcasses with higher muscle content, and improves meat tenderness. The identified changes in gene expression offer valuable insights for further research into understanding the impact of castration on muscle development and fat metabolism in sheep. This meta-analysis contributes to the knowledge of molecular mechanisms involved in fat deposition in sheep, opening avenues for future investigations in livestock fat metabolism research.

The use of condensed tannin in lambs' diet alters the rumen protozoa population without affecting growth performance

The aim of this study was to evaluate the effect of different doses of Black Wattle (Acacia mearnsii) condensed tannin on performance, dry matter intake, blood parameters, and identification and quantification of the rumen protozoa population at fasting and after feeding of feedlot lambs. Sixteen Santa Ines intact ram lambs and sixteen Santa Ines ewe lambs were distributed and randomly assigned to 1 of 4 dietary treatments with different doses of condensed tannin (0 %, 1 %, 2 %, and 3 %) in the concentrate, on a feedlot system. No significant treatment effect (P > 0.05) was observed for growth performance, dry matter intake, and blood parameters. No significant effects of treatment (P > 0.05), phase (fasting and after feeding) (P > 0.05), and interaction between treatment and phase (P > 0.05) were observed for total and differential protozoa percentage. However, differences were observed for total and differential protozoa count. A quadratic effect (P = 0.03) was observed for total counts of Diplodiniinae in the rumen fluid of animals fed 3 % of condensed tannin. A phase effect was observed for counts of Isotricha spp, Entodinium spp. Diplodiniinae, and total protozoa count with higher numbers observed at fasting when compared to after feeding. Results of this research suggest that up to 3 % of black wattle condensed tannin in the diet of lambs does not affect dry matter intake, animal performance, and blood parameters.

Can GPS monitoring help farmers select the best nutritional management strategy for finishing sheep on pasture?

Global Positioning System (GPS) allows monitoring of grazing herds remotely through real-time data collection. We hypothesized that GPS monitoring will establish preferential routes and grazing sites to find the best feeding strategy (supplementation versus no-supplementation) for sheep finished in a Caatinga rangeland (seasonally dry tropical forest) throughout different seasons of the year (rainy period, transition period, and drought period). The experiment was conducted on a 37.9 ha-Caatinga rangeland and comprised 84 days, subdivided into three 28-day periods (rainy, transition, and drought period). Four rumen cannulated sheep were used for estimation of pasture composition during each collection period based on extrusa samples. Twenty-four intact ram lambs (Santa Ines × Dorper F1 crossbred) grazing on Caatinga rangeland were used to test the effects of supplementation on performance, nutrient intake, and nutrient digestibility during the different seasons. The animals were fitted with GPS collars before being released into the Caatinga to monitor their behavioral activity. Greater walking distance, longer grazing time, higher kernel density, and higher walking speed were detected (P < 0.05) for non-supplemented animals, irrespective of season. The supplemented sheep showed greater (P < 0.05) nutrient intake and nutrient digestibility across all experimental periods compared to the non-supplemented animals. Supplemented animals showed greater (P < 0.05) final body weight and average daily gain compared to non-supplemented animals. During the transition and drought periods, supplementation affected all performance variables. In conclusion, GPS is a useful tool to highlight grazing sites according to different seasons and monitor the behavior of F1 Santa Ines × Dorper sheep finished on Caatinga rangeland. Thus, GPS monitoring aids in establishing the best supplementation strategy and consequently reduces productive and environmental losses caused by the spatial distribution of animals and irregular forage use. In addition, supplementation can offset the negative impacts of low forage supply on sheep grazing Caatinga areas.

The effect of weaning age on animal performance in lambs exposed to naturally acquired nematode infections

The effects of mixed gastrointestinal nematode (GIN) infections on animal growth and post-weaning activity patterns were investigated in grazing intact ram lambs when naturally exposed to two different infection levels and weaned at different ages. Ewes and their twin-born lambs were turned-out to graze in two permanent pasture enclosures naturally contaminated with GIN the previous year. Ewes and lambs in the low parasite exposure group (LP) were drenched before turn-out and at weaning, respectively, with 0.2 mg ivermectin per kg body weight, whereas those in the high parasite exposure group (HP) were left untreated. Two weaning ages were applied, early weaning (EW) (10 weeks) and late weaning (LW) (14 weeks), respectively. The lambs were then allocated to one out of four groups based on parasite exposure level and weaning age (EW-HP, n = 12; LW-HP, n = 11; EW-LP, n = 13; LW-LP, n = 13). Body weight gain (BWG) and faecal egg counts (FEC) were monitored, in all groups, from the day of early weaning and every four weeks, for 10 weeks. In addition, nematode composition was determined using droplet digital PCR. Activity patterns measured as Motion Index (MI; the absolute value of the 3D acceleration) and lying time were monitored continuously from the day of weaning until four weeks post-weaning using IceQube® sensors. Statistical analyses were performed in RStudio, using mixed models with repeated measures. BWG was 11% lower in EW-HP compared with EW-LP (P = 0.0079) and 12% lower compared with LW-HP (P = 0.018), respectively. In contrast, no difference in BWG was observed between LW-HP and LW-LP (P = 0.97). The average EPG was higher in EW-HP compared with EW-LP (P < 0.001), as well as in EW-HP compared with LW-HP (P = 0.021), and LW-HP compared with LW-LP (P = 0.0022). The molecular investigation showed that animals in LW-HP had a higher proportion of Haemonchus contortus compared with EW-HP. MI was 19% lower in EW-HP compared with EW-LP (P = 0.0004). Daily lying time was 15% shorter in EW-HP compared with EW-LP (P = 0.0070). In contrast, no difference in MI (P = 0.13) and lying time (P = 0.99) between LW-HP and LW-LP was observed. The results suggest that a delayed weaning age may reduce the adverse effects of GIN infection on BWG. Contrarily, an earlier weaning age may reduce the risk of H. contortus infection in lambs. Moreover, the results demonstrates a potential use of automated behaviour recordings as a diagnostic tool for the detection of nematode infections in sheep.

The Effect of PMSG on Follicular Development and Ovulation Time of PGF2 Treated Awassi Ewes

The objective was to examine the effects of PMSG administration before or at the time of PGF2α injection on reproductive responses of ewes out-of-season. In late June and early July, 57 anestrus ewes were induced to estrus using CIDR-G devices for 12 days. Six days following device removal ewes were randomly allocated into three treatment groups and each received an i.m injection of 20mg PGF2α (day 0, 0 h). PMSG (500 IU) was administered either 24 h before (group A, n=20) or at (group B, n=19) the time of PGF2α injection. Group C ewes (n=18) served as control. Half of the ewes in each group were exposed to three intact rams at 0 h to be naturally mated and the other half were exposed to three aproned rams and inseminated 50-56 h following 0 h. Ewes were checked for breeding marks at 6-h intervals for 4 days. Progesterone levels from day –1 until day 20 were monitored. Occurrence of estrus was similar among ewes of the three treatment groups and averaged 79%. PMSG-treated ewes had shorter (P0.01) intervals to estrus and ovulation, and a higher ovulation rate than non-PMSG treated ewes. Pregnancy and lambing rates were similar among PMSG- and non-PMSG-treated ewes. Although reproductive responses were similar among artificially-inseminated and naturally-mated ewes, the latter had a higher (P0.05) lambing rate (14.3% vs 41.4%, respectively). Ewes inseminated close to the time of ovulation (7.7 h earlier) produced higher (P0.05) pregnancy rate than those inseminated at a wider interval from ovulation (16.7 h earlier). In conclusion, the PGF2α treatment given during luteal phase was effective in resetting subsequent cyclic activity of ewes. Although it did not increase the number of ewes detected in estrus, PMSG shortened intervals to estrus and ovulation, increased ovulation and induced–estrus pregnancy rates.

Discarded pecan seeds as an alternative feedstuff in lamb diets: Effects on intake, growth performance, carcass weights, and meat quality

The aim of this study was to evaluate the effects of feeding discarded pecan seeds on intake, performance, carcass components, and quality attributes of meat from ewe and ram lambs. Twenty-four intact ram lambs and twenty ewe lambs 3.56 ± 0.55 months old weighing 18.01 ± 1.86 kg were randomly assigned to 1 of 4 dietary treatments (0%, 3%, 6%, or 9% inclusion of discarded pecan seeds). After 73 days, at 5.28 ± 0.45 months old with an average body weight of 31.76 ± 3.44 kg, animals were slaughtered. The inclusion of 6% and 9% of pecans increased the deposition of Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) in the lean. Dietary treatments did not affect performance, hot and cold carcass weights, cooling loss, pH, lipid stability, WBSF, color parameters, cooking loss, and proximate values. Lower dry matter intake was observed for animals fed 9% of discarded pecans when compared to animals fed no pecans. Meat from animals fed no pecan seeds was more tender and juicer than lamb fed pecans. Sex affected intake, final body weight, average daily gain, fatty acid profile, color, and fat content. Greater levels of margaric and oleic acids were observed in the lean of ewe lambs whereas meat from rams had greater values of linoleic acid. Atherogenicity, thrombogenicity, and hypocholesterolemia/hypercholesterolemia indeces were not affected by dietary treatments or sex. Meat from ewes was redder, yellower, and fatter when compared to meat from rams. Results of this research suggest that discarded pecan seeds may be used as an alternative feedstuff in lamb diets up to 9%.

Effects of different energy source diets, as corn substitutes, on carcass characteristics and meat quality of feedlot lambs

This study evaluated the effects of different energy sources, as corn substitutes, on the carcass characteristics and meat quality of lambs. Twenty-four intact ram lambs were identified, weighed, and assigned to one of four dietary treatments: corn, citrus pulp, rice bran, and soybean hulls. The ram lambs were confined in feedlots, and when they reached 30 kg of live weight, they were slaughtered. A completelyrandomized design with different replicates was used for the analysis, along with the Tukey-5% test. For hot and cold carcass weight, rice bran produced lower values than the other dietary treatments. For the red color content of the meat, citrus pulp presented superior values when compared to corn, whereas meat and fat color, loin eye area, and objective tenderness did not differ between treatments. Different energetic sources used to replace corn in ram lambs finishing diets did not affect the proximate composition and quality of the meat. Highlights: • Addition of rice bran to the lambs' diet resulted in lower hot and cold carcass weight.• Animals fed soybean hulls presented the highest carcass compactness index values.• Rice bran extended the feedlot period of lambs in 59.33 days, been longer than the others energies sources.• Corn, rice bran, citrus pulp and soybean hulls did not change the quality of meat but the inclusion of rice bran should be carefully evaluated.

Prospective Clinical Study on the Occurrence of Ovine Urolithiasis in Kashmir Valley of India

Background: The study was conducted on confirmed sheep patients suffering from complete retention of urine. Methods: A complete history regarding the age, breed and sex of the animal, castration, duration of illness, managemental practices, feeding habits of the animals, early signs of the disease, previous treatment, if any, were recorded. Result: An overall incidence of 27.11% of obstructive urolithiasis was recorded in sheep. All these cases were intact rams with different age groups, weights and of different breeds. Highest (78.68%) incidence of ovine obstructive urolithiasis was recorded during winter season. Young lambs of 2-6 months of age were found most affected with obstructive urolithiasis (31.14%). Cross bred Kashmir Merino was most affected followed by cross bred corridale (18.3%) and non descript local breeds of ovine (8.9%). The highest (60.65%) cases were brought to the clinics 48-96 hours after the onset of the disease. The cases from far flung areas and hilly terrain were usually received as late as 120-144 hours of illness. The losses could be averted to a great extent by apprising the farmers about the preventive measures of the disease and imparting them training about the balanced feeding and good managemental practices of sheep rearing.

Changes in Cytochrome P450 in Katahdin Ewes Fed Endophyte-infected Tall Fescue Seed Diets in Spring and Fall

Abstract Objective was to examine the activity of cytochrome P450 (CYP), a liver enzyme that metabolizes ergot alkaloids which is hindered by this fescue toxin, as an indicator of fescue toxicosis in sheep. In spring and fall, ewes were blocked by age and BW, and randomly assigned to 1 kg/ewe/d of endophyte-infected (E+; 61% of diet in fall, 13% of diet in spring; 0.8 µg/g of ergovaline; and soy hulls, alfalfa pellets, cottonseed hulls, molasses) or non-infected (E-; same proportion of E+/season and same feeds) tall fescue seed supplement (n = 10/diet in each season) for 28 d, plus hay, mineral and water. Ewes were exposed to teaser, d -21 to 0, and intact rams, d 0 (first day of diet) to 30. Rectal temperature (RT), serum concentration of prolactin (using RIA), and CYP were determined every 7–14 d between d 0–28, and pregnancy status on d 56. PromegaTM P450-Glo assay was used to determine CYP from serum. Data were analyzed by using PROC MIXED with repeated measures (SAS). Rectal temperature of E+ compared with E- ewes was elevated on at least one day in fall and spring (diet × season × d, P &amp;lt; 0.001). Serum prolactin was lower in E+ compared with E- ewes (diet × d, P &amp;lt; 0.001) and lower in fall (P &amp;lt; 0.001). CYP was higher in E- ewes on d 28 in fall (diet × season × d, P = 0.008), but otherwise similar between diets, and higher in fall than spring (P &amp;lt; 0.001). There was an unexpected negative correlation between CYP and prolactin (R = -0.24; P &amp;lt; 0.009), but there appears to be a subpopulation of ewes with low prolactin and lower CYP. CYP activity in sera may not be a marker for fescue toxicosis in ewes.

Effects of dietary energy and protein levels on nutrient intake, digestibility, and body weight change in Hararghe highland and Afar sheep breeds of Ethiopia.

Objectives:The experiment was conducted to determine the effect of dietary energy and protein level growth performances of selected indigenous Ethiopian sheep breeds.Materials and Methods:Fifty intact ram lambs, 25 from each breed with 12 months of age and a mean initial body weight (IBW) of 19.31 ± 1.7 kg, were employed for this experiment. Animals were distributed randomly into five dietary treatments, i.e., minimum Energy and Protein (mEmP), medium energy and protein (MEMP), medium Energy and high Protein (MEHP), high energy and medium protein (HEMP), and high Energy and high Protein (HEHP) diets in randomized complete block design with 2 * 5 factorial arrangements. The minimum, medium, and high energy diets were 2.388, 2.866, and 3.344 Mcal/kg dry matter (DM) with the corresponding 10%, 16%, and 20% crude protein (CP) diets, respectively. The diets were formulated in a total mixed ration from wheat bran (WB), maize grain, peanut cake, and pasture hay feed ingredients. Diet offer was at the rate of 3% of lambs’ live weight and revised biweekly as per the attained body weight changes. Digestibility trial was conducted for 7 days of actual fecal data collection, followed by 90 days of feeding trial.Results:The animals fed on the MEHP diet had a maximum DM and nutrient intakes (CP and organic matter) and the best final body weight (FBW), total gain, gain rate, average daily gains, and feed conversion efficiency (31.3, 12.9 kg, 41.2%, 143.3 gm, and 23.13, respectively), followed by HEMP, HEHP, MEMP, and mEmP diets. Digestibility of DM and nutrients linearly followed similar trends (p < 0.01). Hararghe sheep was heavier (p < 0.01) by 4.3 and 3.1 kg in its FBW and total gain and more efficient in nutrients utilization (22.57 vs. 18.18) as compared to Afar sheep (AS).Conclusion:It is concluded that MEHP and MEMP are superior and optimum diets for sheep breeds, and Hararghe sheep is carried out better than AS in most growth performance parameters.

Extending the interval between second vaccination and slaughter: I. Effects on growth, scrotal size and stress responses of immunocastrated ram lambs

Immunocastration provides a less invasive means of castrating lambs. Considering increasing consumer awareness, the efficacy of this technique on commercial slaughter lambs needs to be further investigated and its effects on growth and stress responses need to be established. This study compared the growth rate, testes size and stress responses of immunocastrated lambs with that of lambs physically castrated with a Burdizzo clamp, as well as intact rams. A total of 40 Dohne Merino ram lambs (average live weight = 45.4±3.68 kg) were randomly allocated to the following four treatment groups: control (intact; R), Burdizzo-castrated (on day 2; B), immunocastrated with a 4-week (ICS4), or a 6-week (ICS6) interval between the second immunocastration vaccination and slaughter. Within the immunocastration treatments, the reaction to vaccination was assessed through injection site scoring, recording the local injection site surface temperature and assigning a walking score. The response to Burdizzo castration was assessed by scoring the reaction during the procedure, testes palpation reaction, walking gait and measuring testis temperature. Additional parameters recorded included BW, serum cortisol concentration, scrotal circumference and rectal temperature. Pain behaviours were described for the short-, medium- and long-term effects after the two methods of castration. Predominantly, tissue-hardening and bruising occurred at the injection sites of immunocastrates, but little effect was observed on walking comfort and no effect on injection site temperature or rectal temperatures. After Burdizzo castration, lambs spent more time in abnormal postures, and from day 3 (D3) to D8 of the trial, discomfort was observed during testes palpation and walking in B lambs. Serum cortisol concentrations were elevated in B lambs on D3 and D15, indicating physiological stress. Thus, immunocastration improved the welfare of castrated lambs as assessed by cortisol secretion, scrotal swelling and pain behaviours, without influencing growth rate.

Pregnancy-associated changes in expression of progesterone receptor and progesterone-induced blocking factor genes in bone marrow of ewes

Progesterone (P4) regulates reproductive and immune functions through binding to the progesterone receptor (PGR), and the effects of P4 are partly mediated by a progesterone-induced blocking factor (PIBF). Bone marrow (BM) is a key component of the lymphatic system and has an important role in immune response. In this study, BM was harvested from femurs on days 13, 16 and 25 of pregnancy and day 16 of the estrous cycles without mated by intact rams, and a qRT-PCR assay, Western blot and an immunohistochemistry analysis were used to analyze the expression of PGR and PIBF genes in BM. The results showed that there was an increase in relative abundance of PGR and PIBF mRNA in BM during early pregnancy, and PGR-B and the full-length PIBF genes were up-regulated in pregnant ewes. Immunohistochemistry results confirmed that the PGR and PIBF proteins were localized in both the cytoplasm and nuclei of adipocytes and the cells in the stroma and capillaries. This is the first study reporting an up-regulated expression of PGR-B and full-length PIBF genes in BM during early pregnancy in sheep. It is suggested that the conceptus exerted its effects on the adipocytes and the cells in the stroma and capillaries in BM, which were involved in the immunoregulation of BM through both cytosolic and nuclear pathways in ewes.

The influence of vaccination interval on growth, carcass traits and testicle parameters of immunocastrated ram lambs

This study determined the effect of different immunocastration vaccine administration intervals on growth, carcass traits and testis development of ram lambs. The trial consisted of four treatment groups of 10 Dohne Merino rams per group. The trial was initiated when the rams were 5.5 months of age, with the control treatment being represented by intact (R) ram lambs. The treatments consisted of two (IC2), three (IC3) and four (IC4) week intervals between the primary and secondary vaccine administration and the total duration of the trial was 9 weeks. Slaughter age was fixed at 4 weeks post second vaccination for all treatment groups. Live body weight, scrotal circumference and temperature as well as injection reaction score and temperature were recorded weekly. At slaughter, the carcass and individual offal items were weighed, and shoulder circumference, neck circumference and subcutaneous backfat thickness measured 24h post-mortem. Vaccination interval was found to influence the average daily gain (ADG) between first and second vaccination; with this difference not observed when ADG was considered for the overall trial period. Vaccination schedule did not influence slaughter weight, carcass weight, subcutaneous backfat thickness, and linear carcass measurements. It was found that vaccination schedule had an effect on the percentage contribution of the gastrointestinal tract to total carcass weight, indicating a possible effect on gut fill. Differences in scrotal circumference between the immunocastrated groups and R were evident from week 4. From week 5, the scrotal circumferences of rams from the IC3 and IC2 treatment groups were smaller when compared to the control group, and remained smaller until the end of the trial. The immunocastration protocols followed in the study thus were successful in inhibiting testis growth and potentially function, without impacting negatively on the overall growth performance and slaughter performance of the ram lambs.

Effect of on farm supplementation of dried Sesbaniasesban (L.) leaf on performance of Abergelle rams

The objectives of the study were to evaluate the effect of supplementation of dried Sesbaniasesban (L) leaf on supplement intake, body weight gain and cost benefit analysis of the feeding regimes for Abergellerams under farmer’s management system in Tigray region, northern Ethiopia. The experiment was carried using 21 yearling intact Abergelle rams with an initial body weight of 22.83 + 3.11Kg (mean + standard deviation). The experiment comprised 90 days of feeding trial after 14 days of adaption period. Farmers having each 3 yearling intact Abergellerams with similar body weight were first purposively identified and then from the identified farmers 7 farmers were randomly selected. Randomized complete block design with 4 treatments and 7 replications was applied. The treatments were local feeding practices (T1), local feeding practices + 250 g -1 day dried Sesbaniasesbania leaf (T2) and local feeding practices + 300 g -1 daydried Sesbaniasesbania leaf (T3). The CP of dried Sesbaniasesban leaf was 23.34%. The DM, OM, CP, NDF, ADF and ADL intakes from the Sasbaniasesban leaf were significantly higher (p<0.0001) for T3 than T2. The average daily gain of Abergelle rams in T2 and T3 were significantly higher (p<0.0001) than T1 but similar in T2 and T3. The average daily gains were 28.98 g, 67.96 g and 75.71 g for T1, T2 and T3, respectively. Supplementation of dried Sesbaniasesba n leaf for Abergelle rams provide more profit compared to unsupplemented rams. Though T2 and T3 given comparable result in terms of body weight gain, the marginal rate of return suggested that supplementation of dried Sesbaniasesban leaf with 250 g -1 day than 300 g -1 day for Abergelle rams provided better economic gain and therefore, T2 is recommended as biological and economical sufficient supplementary regime for Abergelle rams.

Short-term under-nutrition affects feeding and sexual behaviour in oestrous-synchronized Saint Croix ewes (Ovis aries)

ABSTRACTTo determine the effect of short-term under-nutrition on feeding and sexual behaviour in oestrous sheep, the oestrus cycles of 51 Saint Croix ewes were synchronized, and they were randomly assigned to one of two groups. Each group was maintained on a Taiwan grass (Pennisetum purpureum) pasture for 102 h after sponge withdrawal. This diet provided 400 g of dry matter/100 kg of body weight/day, the total available for one group (T), whilst another group (T + C) received an additional 350 g/animal/day of concentrate. Before and after the experimental period, all animals received the additional concentrate. A pen with two one-way gates was located in the centre of each pasture to capture those ewes showing proceptive behaviour towards a ram tethered inside, while sexual receptivity tests were performed every 6 h for 102 h, starting at sponge withdrawal, by moving the ewes to an adjacent pen and exposing them to an intact ram. Foraging behaviour was recorded by scan samples before the sexual receptivity tests. Progesterone concentration was determined on days 2 and 11 after sponge withdrawal. Only 26% of the ewes in the T + C group and none in the T group displayed proceptive behaviour. In both groups, all ewes displayed sexual receptivity and ovulated. Grazing, rumination and walking were higher in T ewes. The frequency and the duration of lying were higher in the T + C than in the T ewes. It was concluded that the short-term nutritional deficiency induced changes in foraging behaviour and decreased ram-seeking behaviour in oestrous-synchronized ewes.

Quantification of the effects of castration on carcass and meat quality of sheep by meta-analysis

After an extensive literature search, meta-analytic techniques (fixed effect, random effects and hierarchical Bayesian models) were applied to numerically describe sizes and precision of effects caused by castration of intact rams on several performance, carcass and meat quality response variables. According to random effects models, rams presented greater (P<0.05) average daily gain, loin muscle area (leaner carcasses) and instrumental meat tenderness (more tough), with lower feed conversion ratios, dressing percentages and backfat thickness (less carcass fat) compared to castrates. These results could be applied in further strategies on the use of castration in male sheep.

Disruption of estrus and conception in the acute phase of Fasciola gigantica infections in Yankasa ewes

The effect of the hepatic migratory phase of Fasciola gigantica infections on estrus response to synchronization, conception rates, serum enzyme and biochemical changes in Yankasa ewes was investigated. Twelve adult Yankasa ewes were randomly assigned to one of two groups of 6 animals each. The ewes in Group 1 were each infected with 1,200 metacercaria of F. gigantica each while Group 2 served as non infected controls for the study. The ewes in both groups were then synchronized for estrus at 7 weeks post infection (WPI), and intact rams were introduced for heat detection and breeding. Pregnancy was confirmed by progesterone levels and non-return to estrus 21 days post breeding. Estrus response was 66.6 and 100% in infected and controls, respectively, but all infected animals returned to estrus by 42 days post breeding, indicating conception failure or an early embryonic death. Pathophysiological signs included anorexia, progressive anemia, emaciation and significant hypoproteinemia. Hepatic dysfunction was indicated by the significant increases in liver enzymes; aspartate amino transferase, alanine amino transferase and alkaline phosphatase levels in infected ewes and at post mortem hepatic fibrosis of the liver with intra-hepatic hemorrhage was observed. It is concluded that fasciolosis has an adverse effect on conception and establishment of the fetus in the acute migratory phase. Key words: Fasciola gigantica, estrus, conception, ewes, productivity, Nigeria.

Maternal Obesity and Overnutrition Is Associated with Reduced Systemic Progesterone During the Estrous Cycles of Adult Female Offspring and a Marked Increase in Insulin Resistance at Midpregnancy.

Previously published studies from our laboratory and others have demonstrated that maternal undernutrition (MU) and overnutrition (MO) alter fetal growth and development during intrauterine life, predisposing offspring to similar metabolic disturbances in postnatal life. We have recently demonstrated that MO predisposes nonpregnant female offspring to hyperphagia, increased obesity, and insulin resistance as adults. Further, we have reported that MU of ewes is associated with increased oxidative base lesions within DNA of mid-gestational (Day 78) fetal oogonia in sheep. More recently we have reported that female offspring born to MU ewes exhibited consistently reduced circulating progesterone concentrations during their estrous cycles, and reduced fertility when compared to female offspring born to ewes fed to NRC requirements. This study evaluated the impact of MO on systemic progesterone concentrations during an estrous cycle, fertility, and insulin resistance of adult female offspring at midgestation. Adult nonpregnant female offspring (2-3 years old) born to obese (OB) overnourished ewes fed 150% of NRC recommendations (n = 10), or 100% of NRC (Controls; CON, n=7) from 60 days prior to conception to term were utilized in this study. During an estrous cycle, ewes were bled daily from one estrus (Day 0) to the next, and serum collected and frozen at -80°C until analyzed for progesterone (P4) via validated RIA. At the second estrus, ewes were hand mated to an intact ram at 12hr intervals until the end of estrus. Conception rates and fetal numbers (singles and twins) were determined via real time ultrasonography, and pregnant ewes were subjected to an intravenous glucose tolerance test (IVGTT) at midgestation (75 ± 1 day). Plasma glucose and insulin was measured in triplicate by colorimetric assay and validated RIA, respectively. Estrous cycle length was reduced (P < 0.05) in the offspring of OB vs. CON ewes (17.2 ± 0.2 days vs. 18.0 ± 0.1 days). Further, serum progesterone concentrations were decreased (area under the curve, P < 0.05) during the estrous cycle of offspring from OB versus CON ewes. Baseline glucose and insulin concentrations were greater (P < 0.05) in offspring from OB vs. CON ewes, (64.03 ± 3.97 vs. 54.68 ± 1.30 mg/dL and 7.01 ± 2.18 vs. 3.43 ± 0.15 mIU/L, respectively). During the IVGTT, glucose concentrations remained greater (area under the curve; P < 0.01) than those of offspring from CON ewes during the post infusion period. Plasma insulin concentrations of OB offspring during IVGTT were also markedly increased (P < 0.03) when compared to offspring from CON ewes. These data suggest that the decrease in systemic progesterone exhibited by the OB offspring during their estrous cycles may contribute to the shortened estrous cycle lengths observed in this group. In spite of the decrease in circulating progesterone of OB offspring, however, conception rate and fecundity remained unaffected. Maternal overnutrition also resulted in a marked insulin resistance at midgestation in offspring of OB vs. CON ewes, suggesting that the F2 generation could exhibit the same metabolic alterations as their mothers resulting in a transgenerational programming effect. Supported in part by NIH INBRE #P20RR016474. (platform)

Nutritional evaluation of elephant-grass silages with byproduct of annato

The objective of the present study was to evaluate the nutritional value of elephant-grass silages containing annato byproduct. Twenty intact rams were distributed in a complete randomized block design with five diets (0; 4; 8; 12 and 16% annato byproduct in the silage) and four replications and used to estimate the intake, apparent nutrient digestibility, content of total digestible nutrients and nitrogen balance. The addition of annato byproduct raised the intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ether extract (EE), total carbohydrates (TC), non-fibrous carbohydrates (NFC) and total digestible nutrients (TDN), in body weight (%BW) and in metabolic weight (g kg-1BW0.75). The digestibilities of DM (55.95%), OM (58.19%), CP (45.34%), NDF (52.79%), ADF (45.79%), EE (34.96%) and NFC (99.86%) were not influenced by the addition of annato byproduct. The inclusion of annato byproduct in elephant-grass silage increased digestibility of total carbohydrates, the TDN content and the nitrogen balance. The aditions of annato byproduct at levels up to 16% of the elephant grass silage natural matter improves nutrient intake and nitrogen balance.

Autoimmunization of ewes against pregnancy-associated glycoproteins does not interfere with the establishment and maintenance of pregnancy

Pregnancy-associated glycoproteins (PAGs) are a large grouping of placental proteins that belong to the aspartic peptidase gene family. Although useful to detect pregnancy in ruminant species, the function of these molecules is unclear. Several PAGs expressed by trophoblast binucleate cells can enter the maternal circulation, suggesting that they could have a systemic role in altering maternal physiology. The objective of this work was to examine whether these circulating placental antigens were important in pregnancy by actively immunizing ewes against them. PAGs were purified by pepstatin-affinity chromatography and conjugated to the immunogenic protein, keyhole limpet hemocyanin (KLH). Ewes were immunized with PAG–KLH conjugate (n = 22) or with KLH alone (n = 9), and bred to intact rams. Blood samples, collected on Day 0 (day of estrus), Day 10, Days 15 to 25 and weekly throughout pregnancy, were analyzed for PAG by an ELISA. On Day 30, pregnancy was confirmed by ultrasound. Ewes immunized against PAG–KLH produced a range of reactive anti-PAG titers, whereas all immunized ewes had high anti-KLH immunoreactivity. PAGs became detectable in the anti-KLH (control) ewes at Day 21.6 ± 2.2 of pregnancy. Those ewes immunized against PAGs (n = 7), that had very low immunoreactivity toward PAGs, had measurable PAG by Day 22.9 ± 1.3, and their PAG serum profiles throughout pregnancy did not differ from the controls. Those exhibiting moderate to high anti-PAG immunoreactivity (n = 15), had significantly lower PAG concentrations than controls, with antigen not becoming detectable until Day 48.1 ± 15.6. The decrease in circulating PAG in the immunized animals did not correlate with changes in pregnancy rates, lamb number or lamb birth weight. These results suggest that while PAGs may play a role in maintaining pregnancy, their major contribution is likely to be at the fetal–maternal interface. Their actions at extra-placental sites are presumably of more secondary importance.