On estimating non‐additive genetic parameters in chickens 1

1. Several economically important traits in two Leghorn populations (over 9000 birds) were examined for additive and non‐additive components of genetic variance and sex‐linked effects. Data were analysed by two different statistical models based on least‐squares procedures.

2. Six different covariances were first calculated between relatives; i.e., full‐sibs, 3/4‐sisters, half‐sisters, dam‐daughters, grandam‐granddaughters and aunt‐nieces.

3. From the covariances, weighted least‐squares equations were used to obtain estimates of variance components for additive genetic, dominance, maternal and sex‐linkage effects.

4. The estimates of non‐additive components were highly variable but generally small compared with the additive genetic estimates.

5. In general this study suggests that for most traits, with the possible exception of rate of egg production, there is relatively little non‐additive genetic variation.

6. The consequences of possible negative correlations between additive effects and maternal effects are considered as they might apply to egg production in poultry.     

Linkage disequilibrium and effective population size in Gir cattle selected for yearling weight

Linkage disequilibrium (LD) plays an important role in genomic selection and mapping of quantitative trait loci (QTL). This study investigated the pattern of LD and effective population size (N_e) in Gir cattle selected for yearling weight. For this purpose, 173 animals with imputed genotypes (from 18 animals genotyped with the Illumina BovineHD BeadChip and 155 animals genotyped with the Bovine LDv4 panel) were analysed. The LD was evaluated at distances of 25–50 kb, 50–100 kb, 100–500 kb and 0.5–1 Mb. The N_e was estimated based on 5 past generations. The r² values (a measure of LD) were, respectively, .35, .29, .18 and .032 for the distances evaluated. The LD estimates decreased with increasing distance of SNP pairs and LD persisted up to a distance of 100 kb (r² = .29). The N_e was greater in generations 4 and 5 (24 and 30 animals, respectively) and declined drastically after the last generation (12 animals). The results showed high levels of LD and low N_e, which were probably due to the loss of genetic variability as a consequence of the structure of the Gir population studied.     

Physicochemical parameters,fatty acid profile,and sensory attributes of meat from lambs fed with cassava dregs in replacement of corn

Tropical Animal Health and Production - The objective of this study was to evaluate the effect of the replacement of corn by cassava dregs (0, 33, 66, and 100%) in the diet of lamb on...     

Effect of floor cooling on performance of lactating sows during summer

Forty Landrace × Large White lactating sows were used to evaluate the effects of cooling of the floor when maintained under high temperature conditions during summer on their productive and reproductive performance. The sows were allocated in a completely randomized design with two treatments with 20 replicates according to parity number and body weight, with each animal being considered an experimental unit. The treatments consisted of cooling of the floor under the sow with water circulation at about 17 °C and no cooling. The resulting temperatures of the floor were 27.6 and 35.8 °C for the cooled and the control treatments, respectively. The sows from both treatments were exposed to average maximum and minimum environmental temperatures of 26.9 and 20.8 °C, respectively. Sows maintained on a cooled floor had a higher feed intake (6.47 vs. 5.61 kg/day; P < 0.01). Despite this higher intake, sows maintained on a cooled floor had higher body weight and body protein losses during the lactation period (P < 0.01) in connection with a higher milk yield and subsequent growth of the litter (2280 vs. 1798 g/day; P < 0.01). There was an effect of treatment on rectal temperature, surface temperatures and respiratory rate (P < 0.01) with lower values in sows submitted to floor cooling. It is concluded that floor cooling under the lactating sow improves its productive and reproductive performance, as well as the performance of its litter.     

Catheter-induced urethral trauma in cats with urethral obstruction

Fifteen cats were evaluated with urethral obstruction. Penile trauma by catheterization was the major indication for perineal urethrostomy. Ten cats had developed a urethral stricture and five had rupture of the urethra following medical management. All cats had abnormalities in penis and/or prepuce and/or scrotal sacs including hyperemia or swelling. Perineal urethrostomy was performed in all cases and they were evaluated for 6 months after surgery. Few complications were noted. Urinary tract infection was the most frequent complication observed. The clients considered their cats to have a good quality of life following surgery.     

Voluntary intake and milk production in F1 Holstein × zebu cows in confinement

The objective of this study was to evaluate the nutrient intake and milk production in Holstein × zebu (F1) cows in feedlot. Eighteen F1 cows were used, divided into three treatments; six were Holstein × Gir (HGI), six were Holstein × Guzerat (HGU), and another six were Holstein × Nelore (HNE), which had recently calved, distributed into simple, random samples, under the same feeding conditions of corn silage and concentrate with 20% crude protein. The three-marker method was used (LIPE, titanium dioxide, and iADF) to estimate the individual intake and digestibility of the nutrients for the cows in group. The mathematical model used to establish the lactation curves was: Y = at(b)e(-ct) by Wood (Nature 216:164-165, 1967). The statistical analyses for the nutrient intake and digestibility, as well as parameters of metabolic efficiency, were performed using multiple linear regression (α = 5%). No effect (P > 0.05) of genetic group was observed for any of the variables studied. The intake and digestibility of the nutrients and the microbial nitrogen presented quadratic curves as a function of the lactation period (P < 0.05). The HGU cows exhibited an accumulated milk production of 4,946.81 kg at 305 days, whereas the HGI cows produced 4,821.78 kg. The HNE cows displayed inferior performance, with a production of 3,674.98 kg. It was concluded that, in confinement, F1 cows from different genetic groups do not exhibit different intake, digestibility, or metabolic efficiency. The HGU and HGI cows have greater cumulative production at 305 days.     

Adenosine deaminase activity in serum, erythrocytes and lymphocytes of rats infected with Leptospira icterohaemorrhagiae

Leptospirosis is a systemic disease of humans and domestic animals, mainly dogs, cattle and swine. The course of human leptospirosis varies from mild to severe fatal forms and the most severe form of human leptospirosis is principally caused by Leptospira interrogans serovar icterohaemorrhagiae (L. icterohaemorrhagiae). The enzyme adenosine deaminase (ADA) plays an important role in the production and differentiation of blood cells. The aim of this study was to evaluate the activity of ADA in serum, erythrocytes and lymphocytes of rats infected with L. icterohaemorrhagiae, as compared with non-infected rats. Twenty-four adult rats, divided into two uniform groups (A and B) were used for the enzymatic assays. The animals in Group B were inoculated intraperitoneally with 2×10(8) leptospires/rat, and the rodents in Group A (control) were not-inoculated. Blood collection was performed on days 5 and 15 post-infection (PI) and the blood used to assess the ADA activity. The infection by L.icterohaemorrhagiae altered erythrocyte count, hemoglobin concentration and hematocrit, causing a decrease in all these parameters on day 15 PI. Lymphocytes decreased significantly on day 15 PI, and ADA activity in serum was inhibited in infected rats on days 5 and 15 PI and its activity in erythrocytes were increased on day 5 PI. On day 5 PI, we found an increase in ADA activity in erythrocytes of infected rats. No correlation was observed between hematocrit and erythrocyte ADA activity on days 5 and 15 PI. The ADA activity was inhibited in rats infected on day 15 PI. A positive correlation (r(2)=60) was also observed between the number of lymphocytes and ADA activity in lymphocytes on day 15 PI (P<0.05). In conclusion, our results showed that the ADA activity is altered in serum, lymphocytes and erythrocytes in experimental infection by L.icterohaemorrhagiae in rats, concomitantly with hematological parameters.     

Poisoning of horses by bamboo, Bambusa vulgaris

The clinical and pathological aspects of a neurological disease observed in 16 horses in Pará, Amazonia, Brazil, are presented. The symptoms were mainly motor incoordination, paresis of the tongue, somnolence, difficulties in apprehension, chewing and swallowing of food, as well as instability and standing with abducted members. The clinical course was subacute or chronic and in most cases was not fatal. Postmortem examination performed in one already very sick, euthanized animal, did not show significant macroscopic lesions; histopathological examination revealed slight edema and degenerative alterations of a few axons, mainly in the medulla oblongata. In all pastures where horses were affected, plenty of bamboo had been eaten, probably because of scarcity of pasture. By feeding large amounts of fresh bamboo leaves of this region, in different growing stages, to three horses (horse 1, 47 g/kg/d for 30 days; horse 2, 10 g/kg/d for 60 days; horse 3, 18 g/kg on the first day, and 31 g/kg/d for 6 more days)—the animals ate the leaves unassisted—it was possible to reproduce nervous symptoms essentially identical to those observed in the natural disease 24 to 72 hours after the first feeding of the plant. In spite of continuous administration of the plant, intensity of the clinical signs did not increase. Based on field observations and comparison of the clinical and pathological pictures seen in the natural and experimental disease, the described illness can be concluded to be caused by the ingestion of large amounts of the leaves of Bambusa vulgaris f. vulgaris.     

Transmission electron microscopy for characterization of acrosomal damage after Percoll gradient centrifugation of cryopreserved bovine spermatozoa

The objective of this study was to characterize acrosomal ultrastructure following discontinuous Percoll gradient centrifugation of cryopreserved bovine sperm. Semen was collected from six bulls of different breeds and three ejaculates per bull were evaluated. Frozen semen samples were thawed and the acrosomal region of sperm cells was evaluated by transmission electron microscopy (TEM) before (n = 18) and after (n = 18) Percoll centrifugation. The evaluation of 20 sperm heads from each of the 36 samples analyzed ensured that a large number of cells were investigated. The data were subjected to analysis of variance at a level of significance of 5%. Percoll centrifugation reduced the percentage of sperm exhibiting normal acrosomes (from 61.77 to 30.24%), reduced the percentage of sperm presenting atypical acrosome reactions (from 28.38 to 4.84%) and increased the percentage of sperm exhibiting damage in the acrosome (from 6.14 to 64.26%). The percentage of sperm with typical acrosome reactions was not significantly different before (3.70%) and after (0.67%) centrifugation. TEM distinguished four different types of acrosomal status and enabled ultrastructural characterization of acrosomal injuries. The percentage of sperm exhibiting normal acrosomes decreased and damage in the acrosome was the most frequent acrosomal injury with the Percoll gradient centrifugation protocol utilized.