Incorporating sheep into dryland grain production systems: III. Impact on changes in soil bulk density and soil nutrient profiles

Changes in soil bulk density and soil nutrient profiles are a major concern of dryland grain producers considering grazing sheep on cereal stubble fields. Our objective was to compare burned, grazed, tilled, trampled and clipped wheat stubble fields on changes in soil bulk density and soil nutrient profiles. Treatments were evaluated in a series of three experiments using a randomized complete block design and four replications at each site. Contrast statements were used to make pre-planned comparisons among treatments. For Experiment 1, treatments were fall tilled, fall grazed, spring grazed, fall and spring combined (Fall/Spr) grazed, and an untreated control. Five mature ewes were confined with electric fence to a 111 m² plot for 24 h for fall and spring grazed plots resulting in a stocking rate of 452 sheeps d/ha. For Fall/Spr, the stocking rate was 904 sheeps d/ha. For Experiment 2, treatments were fall grazed, fall burned, fall tilled, and an untreated control. In Experiment 3, treatments were fall trampling by sheep, spring trampling by sheep, fall and spring combined (Fall/Spr) trampling by sheep, hand clipping to a stubble height of 4.5 cm, and an untreated control. Trampling treatments were done at the same stocking rates as grazing treatments but sheep were muzzled to prevent intake. In Experiment 1, post-treatment organic matter tended to be greater (P = 0.09) in the mean of the grazed treatments than control plots. In all of the experiments, change in soil bulk density, and soil nutrient profiles did not consistently differ (P > 0.07) among treatments in any manner that would suggest a detrimental impact of grazing sheep on small grain residue. These results indicate a strong potential for grazing sheep on grain stubble without adversely impacting soil bulk density or nutrient profiles.     

Incorporating sheep into dryland grain production systems: II. Impact on changes in biomass and weed density

Weed control in fallow management to conserve soil moisture and nutrients is the largest variable cost to dryland grain production. Our objective was to compare burning, grazing, tilling, trampling and clipping wheat stubble fields on changes in total aboveground biomass and weed density. Treatments were evaluated in three experiments using a randomized complete block design for each experiment with four replications at each site. Contrasts statements were used to make pre-planned comparisons. For experiment 1, treatments were fall tilled, fall grazed, spring grazed, fall and spring combined (Fall/Spr) grazed, and an untreated control. For grazing treatments, five mature ewes were confined with electric fence to 111 m² plot for 24 h for fall and spring resulting in a stocking rate of 452 sheep day/ha. For Fall/Spr the stocking rate was 904 sheep day/ha. For experiment 2, treatments were fall grazed, fall burned, fall tilled, and an untreated control. In experiment 3, treatments were fall trampling by sheep, spring trampling by sheep, fall and spring combined (Fall/Spr) trampling by sheep, stubble hand clipped to a height of 4.5 cm, and an untreated control. Trampling treatments were applied at the same stocking rates as grazing treatments but sheep were muzzled to prevent intake. Data were collected in the fall, prior to treatment imposition, and spring, after treatments had been removed. Post treatment biomass and weed density were greater (P < 0.05) in either control or tilled plots when compared to grazed plots. Post treatment biomass and weed density were greater (P < 0.01) for control than burned plots. Post treatment biomass, weed density, and percent change in these variables, did not differ (P > 0.08) between burned and tilled, and burned and grazed treatments. These results indicate the potential for using grazing sheep as a component in fallow management to reduce biomass and control weeds.     

Effect of melengestrol acetate (MGA) treatment or temporary kid removal on reproductive efficiency in meat goats

The use of melengestrol acetate (MGA; Summer) or temporary kid removal (4 weeks postpartum; Fall) for inducing/synchronizing estrus was evaluated in goats. In the first trial, 47 does were group-fed a commercial diet to provide 0.25 mg MGA/doe daily (n = 25) or a control diet (n = 22) for a period of 10 days. Twenty-five of the does lambing in the fall from this experiment were used in a second experiment. Beginning on day 28.1 ± 0.8 of lactation, kids from 13 does (kid removal) were removed from their dams for 2 days while kids from the remaining 12 does (control) remained with the dams. Mature bucks wearing marking harnesses were introduced for mating at the end of MGA treatment (Experiment 1) or at the time of kid removal (Experiment 2). Does fed MGA were mated approximately 2.1 days earlier (P < 0.05) than control does. The percentage of does mated (84% versus 100%), pregnancy rate (58% versus 90%), and kidding rate (58% versus 90%) was lower (P < 0.05) for the MGA-treated versus the control does, respectively. In Experiment 2, does with kids removed were mated approximately 1.3 days earlier than the control does, but the mean weaning weight of the kids (11.0 ± 0.4 kg for both treatments) was not influenced by treatment. The mean pregnancy rate, kidding rate, kid birth weight, or kid weaning weight was not influenced by treatment and averaged 73.0 and 79.0%, 3.3 ± 0.2 and 16.8 ± 0.7 kg for both treatments, respectively. Overall, although not necessary for mating, a decreased time to first mating and increased synchrony of estrus followed both MGA treatment or temporary kid removal. This may be implemented if improved estrus synchrony is desired. However, more research is needed to overcome the decreased fertility recorded following MGA use.     

Foraging selectivity of three goat breeds in a Mediterranean shrubland

Foraging behaviors of the Damascus, Mamber and Boer goat breeds were compared on shrublands of the South Carmel mountain ridge of Israel. Dietary choice was determined for a group of yearling animals of each breed (n = 11 or 12), housed and grazed separately to prevent social facilitation, during a total of 4 (Mamber) or 5 (Damascus and Boer) sessions of four days each in fall 2004 and spring 2005. The proportions in the diet (including concentrate feed) of three main dietary components – Pistacia lentiscus L. (20% tannins), Phillyrea latifolia L. (3% tannins) and herbaceous vegetation – were determined by application of near-infrared reflectance spectroscopy to faecal samples (n = 147). On average, P. lentiscus constituted 14.9% of the DM ingested by Damascus goats, but only 5.6 and 5.0% of that ingested by Mamber and Boer goats, respectively. In the fall season, Damascus goats ingested diets richer in tannins than did Mamber or Boer goats (P < 0.001). In the spring, the contribution of herbaceous vegetation to DM intake was higher in Mamber goats (38.5%) than in the other breeds (27.7%). Boer goats selected the most nutritious diets in terms of crude protein (CP) content and in vitro dry matter digestibility (IVDMD). Despite their differences in foraging selectivity, the local Damascus and Mamber goats selected similar diets in terms of CP and IVDMD. Our data suggests that, of the three breeds examined, the Damascus should provide the best control of P. lentiscus encroachment and the least competition with cattle for green grass in the spring. These findings may help to develop ecologically sound ways of controlling the spread of the tannin-rich shrub P. lentiscus L., which threatens rangeland biodiversity and amenity values in the Mediterranean climatic region of Israel.     

In vitro production of bovine embryos in medium supplemented with a serum replacer: Effects on blastocyst development,cryotolerance and survival to term

In this study, we evaluated a serum replacer (SR; Knockout SR^®, Invitrogen) in our in vitro culture systems. We hypothesized that SR would benefit bovine embryo development, since SR supported survival of embryonic stem cells (which originate from embryos). Experiment 1 compared oocyte maturation with SR versus fetal bovine serum (FBS). Following fertilization, blastocyst development was lower for oocytes matured with SR (21.5 versus 34.1, P < 0.05). Experiment 2 evaluated SR for culturing embryos. Following fertilization, embryos were cultured for 3 days in KSOM, and then assigned to treatments: (1) KSOM static culture (KNM); (2) fresh KSOM (KD3); (3) KSOM + SR or (4) KSOM + FBS and cultured to Day 7 (fertilization = Day 0). Blastocyst development in FBS or SR was higher than either KNM or KD3 (48.2, 47.2, 32.7, and 35.5, respectively, P < 0.05). Experiment 3 evaluated cryosurvival of embryos cultured in the same manner as Experiment 2. On Day 7, embryos were vitrified and upon warming, embryos cultured in SR had greater 24 h survival rates (70.6%) than all other treatments (P < 0.05). Finally, Experiment 4 evaluated effects of SR on pregnancy rate and development to term. Culture in SR was not detrimental to pregnancy or calving rates (50 and 50%, respectively), and SR calves had normal birth weights (mean = 38.8 kg ± 1.5). In conclusion, the use of SR for maturation of oocytes was not beneficial; however, SR enhanced embryo culture by improving development in vitro, cryotolerance and survival, effectively replacing serum in culture.     

Influence of undegraded intake protein on intake,digestion, serum hormones and metabolites,and nitrogen balance in sheep

In Exp. 1, 20 ewes of mixed breeding were fed grass hay : straw mixtures, assigned to one of four supplemental treatments and evaluated during six collection periods. Supplemental treatments were control (no supplement), and low, medium, and high levels (5.2%, 22.1%, and 41.3% of DM, respectively) of undegraded intake protein (UIP). Supplements were formulated to be similar in degraded intake protein (DIP; 21%). Digestibilities of DM, OM, and CP were increased (P < 0.10) with protein supplementation and in medium and high compared with low UIP supplemented ewes. Digestibility of CP also was increased (P < 0.10) in ewes on high compared with medium treatments. Serum insulin was not influenced (P > 0.10) by UIP treatment, except in collection period four. In contrast, serum glucose and growth hormone were not influenced (P > 0.10) by UIP treatment. In Exp. 2, four wether lambs fed the same treatments as in Exp. 1, were used in two 4 × 4 Latin squares trials. In trial 1 lambs received a grass hay diet (6.7% CP) and in trial 2 lambs were fed 40 : 60 blend (6.6% CP) of grass hay and spring wheat straw. In both trials, N intake, urinary N, N digestion, apparent N absorption, and N retention were increased (P < 0.10) with protein supplementation. In addition, in trial 1, urinary N, N digestion, and apparent N absorption were increased (P < 0.10) in medium and high compared with low UIP and also in high compared with medium UIP treatments. In trial 2 of Exp. 2, total feed intake (g/kg BW), digestibility of DM and OM, BW, and fecal N were increased (P < 0.10) with protein supplementation. Organic matter digestion, BW, N intake, and N retention were increased by medium and high compared with low UIP. Fecal N, BW, N intake, and N retention were increased (P < 0.10) in high compared with medium UIP. These data indicate that increasing levels of UIP supplementation increases DM, OM, and CP (N) digestibility, serum urea N concentration, and N retention in sheep fed low quality forage.     

Selection of developmentally competent buffalo oocytes by brilliant cresyl blue staining before IVM

The brilliant cresyl blue (BCB) test determines the activity of glucose-6-phosphate dehydrogenase (G6PDH); the activity of this enzyme is greatest in growing oocytes, but it declines as oocytes mature. The objective was to develop and evaluate this test for assessing development of buffalo oocytes (to select developmentally competent oocytes for increased in vitro embryo production). Oocytes were exposed to BCB stain diluted in mDPBS (DPBS with 0.4% BSA) for 90 min at 38.5 °C in a humidified air atmosphere; those with or without blue coloration of the cytoplasm were designated as BCB+ and BCB−, respectively. In Experiment 1, oocytes were exposed to 13, 26, or 39 μM BCB. There were fewer BCB+ oocytes after exposure to 13 μM BCB (10%) than after exposure to 26 or 39 μM BCB (57.2 and 61.8%; P < 0.05), but there was no significant difference among treatments for blastocyst production rate. In Experiment 2, the diameter of BCB+ oocytes (144.4 ± 4.2 μm; mean ± S.E.M.) was higher (P < 0.05) than that of BCB− oocytes (136.8 ± 4.6 μm). In Experiment 3, oocytes were allocated into three groups: control (immediately cultured); holding-control (kept in mDPBS for 90 min before cultured); and treatment-incubation (incubated with 26 μM BCB). After IVM, oocytes were fertilized in vitro and cultured on an oviductal monolayer. The nuclear maturation rate was higher (P < 0.05) in BCB+ (86.2%), control (83.4%) and holding-control (82.6%) oocytes than BCB− (59.2%) oocytes. The BCB+ oocytes yielded more blastocysts than control or holding-control oocytes (33.4, 20.2, and 21.0%, P < 0.05); blastocyst development was lowest in BCB− oocytes (5.2%). In conclusion, staining of buffalo oocytes with BCB before IVM may be used to select developmentally competent oocytes for increased in vitro embryo production.     

Effects of urea and aqueous ammonia treatment on the composition and nutritive value of maize residues

Two trials were conducted to investigate changes in chemical composition and nutritive value of maize residues treated with urea and aqueous ammonia. In Experiment I, maize stalks, husks and cobs were chopped into pieces of approximately 1 cm length. Aqueous NH₃ (3%) and feed grade urea equivalent to 3% NH₃ were sprayed into 100 g duplicate samples on DM basis, thoroughly mixed, stored in plastic containers and kept for 3 week at ambient temperature (25–27 °C). Proximate composition and in vitro dry matter digestibility of test materials were determined. In Experiment II, 100 kg batches of the maize residues were chopped and treated as in Experiment I but stored in 205 l drums lined with black polythene sheet. Feed intake and nutrient digestibility of treated materials were evaluated with 18 mature WAD sheep averaging 19.8 kg BW. Treatment improved (P < 0.05) intake and digestion coefficients for N, DM, NDF, ADF and OM but there were no differences (P > 0.05) between aqueous NH₃ and urea treatments. Feed grade urea or the equivalent weight of fertilizer grade urea can be used to improve the nutritional value of maize residues for small ruminant feeding during off season periods.     

Effect of a single subcutaneous injection of melatonin on estrous response and conception rate in goats

The objectives of this study were to evaluate the effect of a single subcutaneous injection of melatonin, on estrous induction and conception rate during the non-breeding season at different times of the year. In Experiment 1 the melatonin powder was dissolved in an oily vitamin A, D, E solution and injected subcutaneously randomly to goats in two dose treatment groups of 20 mg (MLT-20; n = 20) and 40 mg (MLT-40; n = 20) in January (winter). Twenty does were injected with 1 ml vitamin A and served as the control. In the MLT-20 treated goats 70% of the does were in estrus within 20.0 ± 2.0 days, whereas in the MLT-40 group 85% of the does were in estrus within 15.5 ± 2.5 days and 100% and 80% of the does, respectively, conceived on mating with the bucks. Only 10% of the untreated control does exhibited estrus, but none conceived. The breeding season was thus initiated earlier by 1–1.5 months in the treated goats. In Experiment 2, goats were treated with similar MLT-20 and MLT-40 treatments in May (spring), with 20 goats in each treatment group and 20 control goats. The proportion of goats that responded to the melatonin treatments was 80% and 90% in the MLT-20 and MLT-40 treatments, respectively, with no significant differences recorded regarding the estrous response. However, in the MLT-20 treatment group the estrous induction interval was significantly longer (P < 0.05), compared to the MLT-40 treatment. The pregnancy rates were not significantly different for the MLT-20 and MLT-40 treatments, with melatonin resulting in significantly higher pregnancy rates than in the control (88.4% versus 33.3%) and the breeding season initiated 2 months earlier. It could be concluded that a single subcutaneous injection of melatonin can initiate the breeding season (irrespective of the season of the year) earlier by 1–2 months in goats and this could be advantageous when using accelerated breeding systems.     

Effect of partial replacement of concentrates with jackfruit (Artocarpus heterophyllus) leaves on growth performance of kids grazing on native pasture of Tripura,India

Fifteen Black Bengal kids of about 3 months of age and body weight ranging from 3.8 to 4.9 kg were randomly distributed into three groups of five. Kids grazed native pasture 8 h/d. The kids in group I received supplementary concentrate (maize 35%, mustard cake 32%, rice bran 30%, mineral mixture 2% and common salt 1%) at approximately 2% of BW. However, 25 and 50% of the concentrate was replaced with jackfruit leaves for groups II and III, respectively. Total dry matter intake (DMI) was significantly higher in groups II and III than for group I due to greater forage consumption. Digestibility of CP (P < 0.05) decreased and that of NDF increased (P < 0.01) with increasing level of jackfruit leaves in the diet. Digestibility of ADF (P < 0.01), hemi cellulose (P < 0.05) and cellulose (P < 0.01) was higher in groups II and III in comparison to group I. Ruminal pH and TVFA concentration were not significantly different among the groups; however, rumen ammonia-N concentration decreased (P < 0.01) with increased level of jackfruit leaves in the diet. Similarly, plasma urea nitrogen and blood glucose levels were also reduced (P < 0.05) with increasing level of jackfruit leaves in the diet Average daily gain (ADG) was 47.33, 45.11 and 35.56 g/d in groups I, II and III, respectively. ADG and DMI/kg gain were not adversely affected when the level of replacement was restricted to 25%; however, at the 50% of replacement both parameters were adversely affected (P < 0.05). From the results of this experiment, it was concluded that jackfruit leaves might replace 25% of the supplemental concentrate for growing kids grazing in native pasture of northeast India.     

Effect of high tannin grain sorghum on gastrointestinal parasite fecal egg counts in goats

The objective of three experiments was to determine the influence of high condensed tannin (CT) grain sorghum on gastrointestinal parasite fecal egg counts (FEC). Sixteen naturally infected Boer crossbred mixed-sex goats were used. Animals that were supplemented with grain daily were removed from pasture and placed in individual pens and fed treatment diets for 21 or 14 days (Experiment 3). Goats were allowed ad libitum access to water and diets containing high or low CT cracked grain sorghum. On day 0 and every 7 days thereafter, PCV, FEC and FAMACHA^® eyelid color scores (EYE; Experiment 1 only) were recorded. For Experiment 1, percentage of animals dewormed, PCV and EYE were not influenced by treatment and averaged 13.6 ± 4.5% per treatment period, 23.4 ± 0.8% and 3.2 ± 0.12, respectively, for all animals. The FEC increased after day 0 for control but not high tannin grain sorghum fed goats (treatment by day interaction, P < 0.02). As expected, EYE and PCV were negatively related (r = −0.45; P < 0.0005). For Experiment 2, there was no influence of diet on PCV or FEC, but there was an effect of day on FEC (P < 0.002) in which all goats had higher FEC on day 0 (1956 ± 219 eggs/g) than any other sampling day. For Experiment 3, there was no effect of feeding high CT grain sorghum on FEC (2992 ± 591 eggs/g) or PCV (25.1 ± 0.5%). In these studies, high CT grain sorghum did not consistently influence FEC and did not impact PCV or number of animals requiring chemical anthelmintic treatment.     

Milk fatty acid composition of dairy cows grazing at two pasture allowances and supplemented with different levels and sources of concentrate

Milk fatty acid (FA) composition of dairy cows from two grazing studies was examined. In the first study, effects of concentrate supplementation and pasture allowance were evaluated using 20 multiparous Holstein cows in five 4 × 4 Latin squares. The four treatments resulted from the combination of two pasture allowances (i.e., low, 25 versus high, 40 kg dry matter/cow/day) and two concentrate supplementation levels (i.e., 0 versus 1 kg concentrate/4 kg milk). No interactions occurred between concentrate supplementation and pasture allowance for milk FA composition. Concentrate supplementation increased short-chain FA content, and reduced the content of long-chain FA, trans11 C18:1, and cis9, trans11 conjugated linoleic acid (CLA) (1.36 versus 1.18 g/100 g). Concentrate supplementation increased saturated FA (58.6 versus 54.0 g/100 g) and reduced unsaturated FA content (39.9 versus 43.8 g/100 g). Grazing at high pasture allowance increased short-, medium-, and long-chain FA content, without affecting cis9, trans11 CLA content. Saturated FA content was higher (57.1 versus 55.6 g/100 g), and unsaturated FA content was lower (41.3 versus 42.5 g/100 g), when cows grazed at high pasture allowance. Concentrate supplementation reduced unsaturated FA and cis9, trans11 CLA in milk of dairy cows grazing at two pasture allowances. In the second study, two experiments evaluated effects of different energy supplements in grazing dairy cows. In Experiment 1, 25 multiparous Holstein cows were assigned to a cracked corn (CC) or a steam flaked corn (SFC) supplement containing 667 g/kg of corn grain plus a pelleted protein/mineral supplement. In Experiment 2, 22 multiparous Holstein cows were assigned to a ground corn grain (GC) or a non-forage fiber (NFF) supplement. The GC supplement contained 850 g/kg of corn grain, and the NFF supplement contained 440 g/kg of non-forage fiber sources (i.e., beet pulp, soyhulls, wheat middlings) that partially replaced corn grain. Milk FA composition was not affected by corn processing or carbohydrate source. The content of short-, medium-, long-chain FA, and cis9, trans11 CLA (2.5 g/100 g in Experiment 1; 2.1 g/100 g in Experiment 2) was similar between supplements in both experiments. The type of supplement did not affect the content of saturated (62.6 g/100 g in Experiment 1; 65.4 g/100 g in Experiment 2) and unsaturated FA (37.5 g/100 g in Experiment 1; 34.6 g/100 g in Experiment 2). Supplementation with supplements differing in the rate and extent of ruminal carbohydrate digestion did not affect the milk FA composition of grazing dairy cows.     

Asymptomatic systemic disease of Canada thistle (Cirsium arvense) caused by Puccinia punctiformis and changes in shoot density following inoculation

Canada thistle (Cirsium arvense) is one of the worst weeds in temperate areas of the world. A rust fungus, Puccinia punctiformis, was first proposed as a biological control agent for C. arvense in 1893. The rust causes systemic disease which ultimately kills C. arvense plants. In 2013 it was demonstrated in four countries, that inoculation of C. arvense rosettes in the fall with ground telia-bearing leaves can initiate epidemics of systemic rust disease with an average of 28% of inoculated rosettes producing a systemically diseased shoot the following spring. Other rosettes that emerged near inoculation points in spring were stunted and appeared diseased. To determine whether other rosettes were diseased, a chemiluminescence western slot blot test, applying polyclonal antibodies raised against P. punctiformis antigens, was developed to detect the fungus in roots. Rosettes were inoculated with telia-bearing leaves in the fall in Maryland, USA and Veroia, Greece. Roots of asymptomatic rosettes that emerged adjacent to inoculation points the following spring were tested for the presence of the fungus with the slot blot test. Rosettes that had diseased shoots were recorded. Based on the slot blot tests, 50–60% of the asymptomatic rosettes adjacent to inoculation points were positive for presence of the rust and likely to be systemically diseased. To demonstrate that systemic disease leads to C. arvense decline, C. arvense shoot densities were measured annually at 10 sites, in three countries, that had been inoculated with telia-bearing leaves in the fall between 2008 and 2012. Changes in C. arvense shoot densities over time were calculated. Average reductions in C. arvense density across the 10 sites were 43.1 ± 10.0% at 18 months after inoculation, 63.8 ± 8.0% at 30 months after inoculation, and 80.9 ± 16.5% at 42 months after inoculation, and 72.9 ± 27.2% at 54 months after inoculation; the 54 month reduction was, however, based on only two sites.     

Long-term effects and persistence of Steinernema scarabaei applied for suppression of Anomala orientalis (Coleoptera: Scarabaeidae)

The entomopathogenic nematode, Steinernema scarabaei, is adapted to scarab larvae as hosts and has already shown exceptional potential for inundative control of these pests. To determine the long-term effects of S. scarabaei application on scarab populations and the nematode’s persistence, S. scarabaei was applied in mid-September at rates from 0.06 to 2.5 × 10⁹ infective juveniles (IJs)/ha to turfgrass plots seeded with oriental beetle, Anomala orientalis, larvae. Scarab and nematode populations were monitored for 3–4 years thereafter. S. scarabaei provided excellent A. orientalis control (77–100%) within 1 month of application at rates of 0.25–2.5 × 10⁹ (IJs)/ha and particularly in the following spring at rates of 0.1–2.5 × 10⁹ (IJs)/ha (86–100%). S. scarabaei provided significant control in the next A. orientalis generation in two out of 10 treatments in fall (i.e., 13 months after application) and six out of 10 treatments in the following spring. Thereafter, significant control was only observed occasionally. S. scarabaei numbers were highly variable, and few significant differences among treatments were observed. S. scarabaei recovery from the treated plots was generally more consistent through the first spring after application and became more variable thereafter, but S. scarabaei was recovered for up to 4 years in the experimental plots. Endemic populations of Heterorhabditis bacteriophora and Steinernema carpocapsae, regularly recovered from the experimental plots and often in higher numbers than S. scarabaei, had no significant effect on A. orientalis densities but were able to coexist with S. scarabaei. Our observations suggest that, once current problems with its mass production can be overcome, S. scarabaei could be augmented periodically in areas with recurrent scarab infestations to provide long-term suppression.     

Effects of feeding system on carcass and non-carcass composition of Churra Tensina light lambs

Thirty-eight single male lambs (3.6 ± 0.08 kg live weight at birth) were used to study the influence of feeding system on carcass and non-carcass composition of Churra Tensina light lambs. Treatments: indoor (IND), lambs housed indoors consuming concentrate ad libitum until weaning at 53 days of age, and ewes grazing 8 h a day without their offspring and receiving a supplement of barley meal after grazing; grazing (GR), ewes and lambs grazed continuously without concentrate and lambs were unweaned. When lambs reached 22–24 kg live weight they were slaughtered. Carcass and non-carcass composition was recorded. GR lambs displayed higher carcass shrink (P < 0.05) and lower dressing percentage (P < 0.01) than concentrate-fed lambs. IND lambs had more body fat mainly due to the heavier kidney (P < 0.001) and subcutaneous (P < 0.001) fat depots. Total non-carcass weight was not affected by treatment (P > 0.05), but red organ (heart, lung and trachea, thymus, liver, spleen, kidney, diaphragm, pancreas, gall bladder, bladder, and testicles and penis), digestive tract (stomach, small intestine and large intestine) and head, skin, and feet (HSF) weights differed between treatments (P < 0.05). IND lambs had heavier red organs and HSF (P < 0.05) although this difference disappeared when expressed as a percentage of empty body weight. Small intestine weight in grazing lambs was heavier (P < 0.001) and, consequently, the total digestive tract differed similarly (P < 0.01). Treatment influenced the weights (P < 0.05) of all joints except leg (P > 0.05), showing heavier joints for IND carcasses. The feeding system had a greater effect on subcutaneous fat (P < 0.001) than on intermuscular fat (P < 0.05) in most of the standardized joints. IND carcasses produced a greater proportion of muscle/bone in all joints, except neck, whereas GR produced a greater proportion of muscle/total fat due to the lower amount of fat recorded in this treatment. The percentage of fatty acids was not affected by treatment (P > 0.05) although the percentage of C18:3 was greater and the ratio of C18:2/C18:3 was lower in grazing-fed lambs. The absence of any effect of treatment on the fatty acid percentages may be influenced by the short raising period and by the similar amount of intramuscular fat in both treatments. It is concluded that light lambs reared under grazing conditions can produce carcasses of acceptable quality, due to the lower percentage of subcutaneous fat, but with a similar intramuscular fat content.     

Haemodynamics and stresses in abdominal aortic aneurysms: A fluid-structure interaction study into the effect of proximal neck and iliac bifurcation angle

Our knowledge of how geometry influences abdominal aortic aneurysm (AAA) biomechanics is still developing. Both iliac bifurcation angle and proximal neck angle could impact the haemodynamics and stresses within AAA. Recent comparisons of the morphology of ruptured and intact AAA show that cases with large iliac bifurcation angles are less likely to rupture than those with smaller angles. We aimed to perform fluid-structure interaction (FSI) simulations on a range of idealised AAA geometries to conclusively determine the influence of proximal neck and iliac bifurcation angle on AAA wall stress and haemodynamics.Peak wall shear stress (WSS) and time-averaged WSS (TAWSS) in the AAA sac region only increased when the proximal neck angle exceeded 30°. Both peak WSS (p < 0.0001) and peak von Mises wall stress (p = 0.027) increased with iliac bifurcation angle, whereas endothelial cell activation potential (ECAP) decreased with iliac bifurcation angle (p < 0.001) and increased with increasing neck angle.These observations may be important as AAAs have been shown to expand, develop thrombus and rupture in areas of low WSS. Here we show that AAAs with larger iliac bifurcation angles have higher WSS, potentially reducing the likelihood of rupture. Furthermore, ECAP was lower in AAA geometries with larger iliac bifurcation angles, implying less likelihood of thrombus development and wall degeneration. Therefore our findings could help explain the clinical observation of lower rupture rates associated with AAAs with large iliac bifurcation angles.     

Effect of grazing and homeopathy on milk production and immunity of Merino derived ewes

The effect of grazing and homeopathic therapy on sheep immune response and milk production was investigated on 40 multiparous Merino derived ewes. Twenty animals were housed in an indoor-bedded pen (P), whereas 20 others were allowed to graze on pasture for 9 h/d (G). P and G animals were fed an equivalent diet in terms of dry matter intake, crude protein percentage and energy concentration. In each group, 10 animals were subjected to unicistic homeopathic treatments (H), while 10 ewes were kept as a control and treated with conventional medicine when necessary (C). The grazing rearing system had a marked positive effect on in vivo cellular immune response (delayed-type hypersensivity to PHA, P < 0.001). Grazing animals produced more milk than the penned ones (1048.00 ± 75.61 kg versus 853.04 ± 67.78 kg, P < 0.05), with increased content of milk fat (7.69 ± 0.15% versus 7.25 ± 0.14%, P < 0.05). Accordingly, blood levels of triglycerides (P < 0.01), urea (P < 0.001) and alanine aminotransferase (ALT) (P < 0.001) were significantly higher in group G. The homeopathic treatments produced limited effects on the milk production and immune response. However, such treatments reduced the risk of contamination of the products with medicinal traces, as H group received no allopathic treatment.     

Enzyme supplementation of wheat-based diets for broilers: 1. Effect on growth performance and intestinal viscosity

The influence of enzyme supplementation on performance and intestinal viscosity of male broiler chickens fed with diets containing high amount of wheat was examined in three experiments. In the first experiment, addition with an enzyme preparation including different cell wall degrading enzymes to diets containing 63 g kg⁻¹ and 72 g kg⁻¹ of wheat improved (P<0.05) feed conversion efficiency in the 72 g kg⁻¹ wheat diet. In addition, intestinal viscosity of chickens fed with the 72 g kg⁻¹ wheat diet was reduced (P<0.05). Weight gain and feed intake were not influenced by enzyme addition. In Experiments 2 and 3, the inclusion level of wheat in the diets was more than 80 g kg⁻¹ and four different enzyme preparations were used (two xylanase preparations, two mixed preparations). Overall, a significant effect on performance and intestinal viscosity of chickens was obtained as a result of enzyme supplementation in both experiments. In the first 21 days, improvements (P<0.05) in weight gain and feed conversion efficiency were found to be on average 5% and 6% in Experiment 2 and 7% and 8% in Experiment 3, respectively. When weight gain and feed conversion efficiency were examined on a weekly basis it was shown that the significant response of enzyme addition was confined to the first 4 weeks. However, the effect of enzyme supplementation was still significant in the whole period from 21–42 days. Feed intake was not influenced by enzyme addition. The viscosity of intestinal content in both the jejunum and ileum was in general reduced (P<0.05) with enzyme supplementation, the xylanase preparations proving to be the most efficient. It was concluded that enzyme supplementation of wheat-based diets resulted in improved performance of broiler chickens, which was related to a concomitant reduction in intestinal viscosity. However, the response of enzyme supplementation was most pronounced in diets with a wheat content higher than 80 g kg⁻¹.     

Growth and cashmere production by Spanish goats consuming ad libitum diets differing in protein and energy levels

Thirty-six Spanish goat wethers (196 ± 12.9 days of age and 17.5 ± 4.60 kg BW at experiment initiation) from a herd previously selected for cashmere growth were used to determine effects and interactions of ad libitum consumption of diets differing in concentrations of CP (10% and 15%) and ME (2.00, 2.35 and 2.70 Mcal/kg; DM basis) on growth and cashmere fiber production in an 84-day, fall-season experiment. DM intake was greater (P < 0.05) for diets with 15% vs. 10% CP (736 vs. 655 g/day) but similar among ME concentrations (P > 0.10). ADG was greater (P < 0.02) for 15% vs. 10% CP (79 vs. 53 g/day) and increased linearly (P < 0.10) as dietary ME level increased (58, 62 and 78 g/day for 2.00, 2.35 and 2.70 Mcal/kg ME, respectively). Total fleece weight at the end of the experiment was similar (P > 0.10) between CP levels but increased linearly (P < 0.03) as ME concentration in the diet increased (197, 239 and 227 g/day). Guard hair weight was not affected by dietary treatments (P > 0.10); cashmere length was similar among treatments (P > 0.10); and cashmere fiber diameter was not altered by dietary ME level (P > 0.10) but was greater (P < 0.05) for 15% vs. 10% CP (16.92 vs. 16.06 μm). Cashmere weight was influenced by an interaction between CP and ME levels (P < 0.05); cashmere fiber weight with 10% CP was 92, 82 and 95 g, and with 15% CP was 63, 115 and 99 g for 2.00, 2.35 and 2.70 Mcal ME/kg diets, respectively (SE = 10.2). However, the ranking of treatment means for initial cashmere fiber weight was similar to that at the end of the experiment, although differences at the beginning were non-significant and of lesser magnitude than at the end. In conclusion, further research with influences of concentrations of CP and ME in diets consumed ad libitum on cashmere fiber growth of growing US Spanish wether goats is required, and animal numbers and allocation to treatments deserve careful consideration in studies of cashmere fiber production.     

Growth performance and carcass traits of forage-fed hair sheep wethers

The objective of the present study was to compare live animal performance and carcass characteristics of 3/4 or 7/8 Dorper (DO; n = 30), purebred Katahdin (KA; n = 20), purebred St. Croix (SC; n = 17) and purebred Suffolk (SU; n = 10) lambs born in the spring and fall of 2001. After weaning, lambs were supplemented with up to 680 g of a corn-soybean meal supplement while grazing bermudagrass pastures overseeded with ryegrass. Lambs were slaughtered at approximately 210 d of age. From birth to weaning, DO lambs gained faster (P < 0.001) than KA or SC lambs, whereas KA lambs had higher (P < 0.001) ADG than SC lambs. Additionally, DO and SU wethers had greater (P < 0.02) ADG from weaning to slaughter than SC or KA wethers. Suffolk lambs were heavier (P < 0.001) at slaughter and produced heavier (P < 0.001) carcasses than lambs from hair-sheep breeds. Carcasses of KA lambs were fatter (actual fat thickness; P < 0.02) resulting in higher yield grades (P < 0.03) than carcasses of DO, SC, or SU lambs. Carcasses of DO and SU had larger (P < 0.001) longissimus muscle (LM) areas than those of KA or SC carcasses, whereas kidney fat weight and percentage were greater (P < 0.001) in carcasses from KA and SC than DO and SU lambs. Lean maturity was similar (P = 0.32) among breed-types. However, skeletal maturity was greater (P < 0.001) in SU than hair-sheep carcasses. Flank-streaking scores were similar (P = 0.19) among the breed-types, but conformation scores were higher (P < 0.001) for DO and SU carcasses and resulted in higher (P < 0.001) quality grades than SC carcasses. The LM of SU lambs was lighter (higher L^* values; P < 0.05) than that of KA and SC lambs, whereas the LM from DO lambs was redder (higher a^* values; P < 0.001) than SC and SU and more (P < 0.001) yellow than that of the other breed-types. Chops from SU lambs were tougher (higher shear force values; P < 0.007) than chops from the hair-sheep breeds. Results of this study indicate that ADG, carcass muscularity and meat quality were similar between DO and SU lambs, and, although fatter, carcass muscularity of KA was similar to that of DO lambs.