Herbage intake of dairy cows in mixed sequential grazing with breeding ewes as followers

This study aimed to evaluate the hypothesis that mixed sequential grazing of dairy cows and breeding ewes is beneficial. During the seasons of spring–summer 2013 and autumn–winter 2013–2014, 12 (spring–summer) and 16 (autumn–winter) Holstein Friesian cows and 24 gestating (spring–summer) and lactating (autumn–winter) Pelibuey ewes grazed on six (spring–summer) and nine (autumn–winter) paddocks of alfalfa and orchard grass mixed pastures. The treatments “single species cow grazing” (CowG) and “mixed sequential grazing with ewes as followers of cows” (MixG) were evaluated, under a completely randomized design with two replicates per paddock. Herbage mass on offer (HO) and residual herbage mass (RH) were estimated by cutting samples. The estimate of herbage intake (HI) of cows was based on the use of internal and external markers; the apparent HI of ewes was calculated as the difference between HO (RH of cows) and RH. Even though HO was higher in CowG, the HI of cows was higher in MixG during spring–summer and similar in both treatments during autumn–winter, implying that in MixG the effects on the cows HI of higher alfalfa proportion and herbage accumulation rate evolving from lower residual herbage mass in the previous cycle counteracted that of a higher HO in CowG. The HI of ewes was sufficient to enable satisfactory performance as breeding ewes. Thus, the benefits of mixed sequential grazing arose from higher herbage accumulation, positive changes in botanical composition, and the achievement of sheep production without negative effects on the herbage intake of cows.     

Virulence traits of avian pathogenic (APEC) and fecal (AFEC) <Emphasis Type="Italic">E. coli</Emphasis> isolated from broiler chickens in Algeria

Avian pathogenic E. coli (APEC) is the etiologic agent of avian colibacillosis, the most common disease responsible for chicken morbidity in the world. Although multiple virulence-associated factors were identified, their prevalence in Algeria is still poorly known. In the present research, 92 avian pathogenic E. coli (APEC) isolates were recovered from broilers with clinical signs and lesions of colibacillosis. In addition, 32 E. coli isolates collected from feces of healthy birds (AFEC) were included for comparison. All isolates were investigated by PCR for the presence of a total of 11 virulence-associated genes described for avian pathogenic (iroN, ompT, hlyF, iss, iutA, and fimC) and diarrheagenic E. coli (eae, stx, elt/est, ipaH, and aggR). The sensitivity of 39 APEC isolates to 16 antibiotics was also determined using antimicrobial pretreated microplates. Here, we report that 98% of the examined isolates host at least one of the tested virulence factors. The most prevalent genes in APEC were iutA (90.6%), ompT (86.9%), and iss (85.8%); whereas, iutA (78.1%), fimC (78.1%), and iroN (68.7%) were the highest prevalent genes in AFEC. Our data showed that none of the AFEC isolates harbor any of the tested diarrheagenic genes. Moreover, only elt/est (5.4%), stx (2.1%), and ipaH (2.1%) genes were carried by APEC isolates. We further established that ceftazodime, ceftiofur, mequindox, amoxicillin/clavulanic acid, and meropenem were the most efficient antibiotics against the analyzed APEC isolates. Overall, our findings provide more insights about APEC and AFEC virulence potential in Algeria which could participate in the fight against colibacillosis.     

Feeding behavior of feedlot lambs fed diets containing levels of cassava wastewater

In this study, we evaluated the effects of including cassava wastewater in the diet on the feeding behavior of feedlot lambs in 35 male uncastrated Santa Inês × Dorper crossbred lambs at an approximate age of 3 months, with an average live weight of 20.0?±?3.4 kg. Diets were formulated with hay of cassava shoots (roughage) and a concentrate based on corn and soybean, with a roughage:concentrate ratio of 50:50, plus inclusion of cassava wastewater at the levels of 0, 12, 24, 36, or 48 g/kg of the total diet. Feeding behavior was evaluated between the 46th and 52nd days of the experiment. Increasing cassava wastewater levels in the diet reduced (P?<?0.05) the intakes (kg/day) of dry matter and neutral detergent fiber as well as the efficiency of rumination (g/cud and g/h) of dry matter and neutral detergent fiber. The other behavioral parameters were not affected by wastewater inclusion in the diet. Therefore, the inclusion of up to 48 g/kg of cassava wastewater on fresh matter of diets is not recommended for feedlot lambs.     

Prevalence and risk factors of mycobacterial infections in farm and trade cattle in southwestern Nigeria

We evaluated the prevalence of mycobacterial infections (i.e., Mycobacterium bovis and non-tuberculous mycobacteria [NTM]) and their associated risk factors among cattle herds and trade cattle in southwestern Nigeria. Through cross-sectional study design, cattle herds from three locations were screened using the single intradermal comparative cervical tuberculin test based on two diagnostic standards; more than 4 mm (? 4 mm) and more than 2 mm (? 2 mm) cut-off points. Abattoir study involved screening trade cattle for tuberculous lesions. Overall, 515 cattle from 45 herds were screened. Using >?4 mm, animal level and herd prevalence of 11.7 and 46.7% were recorded, respectively. Applying the ? 2 mm cut-off, animal level and herd prevalence increased to 31.1 and 60.0%, respectively. Significantly, using the ? 2 mm cut-off, cattle in medium size herds/extensive management system (OR?=?1.6; 95% CI 1.1–2.5) and Sokoto Gudali (OR?=?2.3; 95% CI 1.4–3.8) were more at risk of being positive reactors, while Rahaji (OR?=?0.3; 95% CI 0.1–0.7) breeds of cattle and cows in the peri-urban area (OR?=?0.4; 95% CI 0.2–0.9) were less at risk of being positive reactors. Again, M. avium reactor of 21.7% was observed. In the abattoir, 1797 cattle were examined with 126 lesions suggestive of tuberculosis (TB). Culture/molecular analyses confirmed 2.2% M. bovis and 0.9% NTM infections. Risk factors associated with bovine TB among trade cattle were sex (OR?=?4.0; 95% CI 1.2–13.5) and age (OR?=?0.3; 95% CI 0.1–0.9). We confirm 11.7% prevalence of mycobacterial infections among populations of cattle screened with breed and herd size being major risk factors.     

Effects of p.o. administered xylitol in cats

Xylitol is commonly used as sugar substitute in households. While it has numerous beneficial effects on human health, it is highly toxic to dogs. The goal of this study was to examine whether xylitol has similar deleterious effects, such as hypoglycaemia and acute hepatic failure, on cats. Our research included six healthy middle‐aged cats. Xylitol was dissolved in deionized water and administered p.o. at three doses (100, 500 and 1,000 mg/kg body weight). These dosages have been considered toxic and can cause liver failure or even death in dogs. After every xylitol administration, the basic health status and the blood glucose of cats were observed regularly. Additionally, prior to and 6, 24 and 72 hr after xylitol administration, blood samples were taken to check complete blood count, clinical biochemical parameters and enzymes such as ALT, ALKP, GGT, GLDH, bile acids, BUN, creatinine, phosphate, total protein, albumin, sodium and potassium. There were no significant changes (p > .05) in any of the haematological or biochemical parameters. Blood glucose concentrations did not show any significant alterations, except at 1,000 mg/kg dose, where a mild but significant increase was observed, but it was in physiological range. Based on our results, xylitol did not induce toxic effects on cats.     

Effect of resistant starch on the intestinal health of old dogs: fermentation products and histological features of the intestinal mucosa

The effects of resistant starch (RS) intake on nutrient digestibility, microbial fermentation products, faecal IgA, faecal pH, and histological features of the intestinal mucosa of old dogs were evaluated. The same formulation was extruded in two different conditions: one to obtain elevated starch cooking degree with low RS content (0.21%) and the other lower starch cooking with high RS content (1.46%). Eight geriatric Beagles (11.5 ± 0.38 years old) were fed each diet for 61 days in a crossover design. Food intake, nutrient digestibility, fermentation products, faecal pH, and faecal IgA were examined via variance analysis. Histological results of intestinal biopsies were assessed via Wilcoxon test for paired data. The morphometric characteristics of large intestine crypts were evaluated via paired t tests (p < .05). Protein, fat, and energy digestibilities were higher for the low‐RS diet (p < .05). Dogs receiving the high‐RS diet had lower faecal pH and higher values for propionate, butyrate, total volatile fatty acids, and lactate (p < .05). No differences between diets were found in the histological parameters of the gut mucosa, and only a tendency for deeper crypts in the descending colon was observed for dogs fed the high‐RS diet (p = .083). The intake of a corn‐based kibble diet manufactured with coarse ground raw material and low starch gelatinization to obtain 1.4% of RS affected microbial fermentation products and faecal pH and tended to increase crypt depth in the descending colon of old dogs.     

Effect of feed intake level and dietary protein content on the body temperature of pigs housed under thermo neutral conditions

Feed intake and diet composition appear to affect the body temperature of pigs. Two trials were conducted to analyse the effect of feed intake level and dietary protein content on the intestinal temperature (IT) of pigs housed under thermo neutral conditions. Ten pigs (64.1 ± 1.3 kg initial body weight) fitted with an ileal cannula were used. A thermometer set to register the IT at 5‐min intervals was implanted into the ileum through the cannula. In both trials, the ambient temperature ranged from 19.1 to 21.6°C and the pigs were fed at 07:00 and 19:00 hr (same amount each time). In trial 1, the pigs were fed daily 1.2 or 1.8 kg of a wheat–soybean meal diet. The IT followed a similar pattern along a 24‐hr period regardless the feed intake level. The IT rapidly increased up to 0.61 and 0.74°C after the morning meal and up to 0.53 and 0.47°C after the evening meal in pigs fed 1.2 and 1.8 kg/d respectively. The postprandial IT was higher in pigs fed 1.8 kg after each meal (p < .05). In trial 2, pigs were fed daily 1.8 kg of a low (11%) or a high (22%) crude protein diet. The IT followed a similar pattern along the 24‐hr period regardless the dietary protein level. The postprandial IT did not differ between pigs fed the low protein or the high protein (p > .10). The IT rapidly increased up to 0.66 and 0.62°C after the morning meal in pigs fed the high‐ and low‐protein diet (p < .05), but there was no change after the evening meal (p > .10). In conclusion, the feed intake level affected the IT of pigs housed under TN conditions, but the dietary protein content had no effect.     

Single step genomic evaluation for female fertility in Nordic Red dairy cattle

Joint Nordic (Denmark, Finland, Sweden) genetic evaluation of female fertility is currently based on the multiple trait multilactation animal model (BLUP). Here, single step genomic model (ssGBLUP) was applied for the Nordic Red dairy cattle fertility evaluation. The 11 traits comprised of nonreturn rate and days from first to last insemination in heifers and first three parities, and days from calving to first insemination in the first three parities. Traits had low heritabilities (0.015–0.04), but moderately high genetic correlations between the parities (0.60–0.88). Phenotypic data included 4,226,715 animals with records and pedigree 5,445,392 animals. Unknown parents were assigned into 332 phantom parent groups (PPG). In mixed model equations animals were associated with PPG effects through the pedigree or both the pedigree and genomic information. Genotype information of 46,914 SNPs was available for 33,969 animals in the pedigree. When PPG used pedigree information only, BLUP converged after 2,420 iterations whereas the ssGBLUP evaluation needed over ten thousand iterations. When the PPG effects were solved accounting both the pedigree and the genomic information, the ssGBLUP model converged after 2,406 iterations. Also, with the latter model breeding values by ssGBLUP and BLUP became more consistent and genetic trends followed each other well. Models were validated using forward prediction of the young bulls. Reliabilities and variance inflation of predicted genomic breeding values (values for parent averages in brackets) for the 11 traits ranged 0.22–0.31 (0.10–0.27) and 0.81–0.95 (0.83–1.06), respectively. The ssGBLUP model gave always higher validation reliabilities than BLUP, but largest increases were for the cow fertility traits.     

Sex‐dependent responses of perch to changes in water clarity and temperature

Rising temperatures and decreasing water transparency of lakes have strong wide ranging effects on fish. Fish responses to various changes in the environment are usually species‐dependent, but responses may also vary within species. In general, large individuals are considered to be more sensitive to environmental variation due to higher energy demand, than smaller individuals. Similarly, large individuals require more food to maintain bodily functions and are thus more sensitive to resource and food scarcity. These size‐specific responses to environmental gradients are also sex‐dependent in species that exhibit sexual size dimorphism (SSD). We studied in enclosures with short‐term experiments how rising temperatures and decreasing water transparency regulate the feeding rates of female and male European perch (Perca fluviatilis L.). To explore experimental results, we calculated perch SSD in nine lakes with varying environmental conditions using previously collected field data. The results of the experiments revealed that the combined effect of water transparency and temperature on the feeding rate of fish is gender‐dependent: feeding rate of females decreased more than that of males. The experimental results were also supported by field data that revealed a negative relation between water transparency and the magnitude of SSD in perch. Our results suggest that rising temperatures and decreasing water transparency may potentially decrease fish size in a sex‐dependent manner. As female size is one of the main demographic traits determining the reproductive success of a fish population, changing environments may have unexpected and far‐reaching consequences on fish population dynamics.     

Symbiotic N<Subscript>2</Subscript> fixation and nitrate utilisation in irrigated lucerne (<Emphasis Type="Italic">Medicago sativa</Emphasis>) systems

Symbiotic N₂ fixation by lucerne (Medicago sativa) has capacity to provide significant inputs of N to agro-ecosystems, and the species has also been shown to scavenge soil mineral N and thus act as a sink for excess reactive N. The balance between these two N cycle processes was investigated in an extensive irrigated lucerne growing region where nitrate contamination of groundwater has been reported. We sampled 18 permanent pure lucerne stands under irrigation for standing dry matter, total shoot N, and N₂ fixation using ¹⁵N natural abundance along with activity of the inducible enzyme nitrate reductase as indicators of use of soil NO₃⁻ by lucerne. On average 65% of lucerne N was obtained from symbiotic N₂ fixation. Converting standing dry matter estimates to annual N₂ fixation amounts we calculated average N₂ fixation of 311 kg N/ha, including N in roots and nodules. Uptake of N from soil by lucerne was calculated to be 181 kg N/ha/year. We were not able to identify the source of this soil mineral N, although nitrate reductase activity of lucerne was higher than that of non-N₂ fixing species examined.