The effect of water depletion on renal excretion of urea and electrolytes in sheep

Experiments were conducted with the sheep of Merino breed given water only at a rate corresponding to 0.5% of their live weight for three days. The animals were given feed ad libitum and during the control measurements water was also available to them ad lib. The fourth day the sheep were given no water and no feed and their renal functions were measured by the standard clearance technique. In the water-depleted sheep the diuresis was naturally reduced and the glomerular filtration rate (GFR) was also observed to have decreased from 77.6 +/- 5.3 to 62.2 +/- 4.2 ml X min-1, P less than 0.05. A small, though significant, decrease was also recorded in plasma urea concentration as a result of the reduced intake of food. The amount of excreted urea decreased by 41% (from 354.0 +/- 41.6 to 208.5 +/- 25.5 mumol X min-1, P less than 0.01) without significant changes in fractional excretion and tubular reabsorption of urea. After three days of water depletion the sheep exhibited a tendency of slight natriuresis whereas the excretion of potassium was reduced. Water depletion was also accompanied by a significant increase in the osmolality of plasma (from 298.0 +/- 1.3 to 317.0 +/- 1.8 mosmol X kg-1 H2O, P less than 0.001) and urine from 789.0 +/- 95.0 to 1547.0 +/- 53.0 mosmol X kg-1 H2O, P less than 0.001), without changes in the clearance of free water. On the other hand, the osmotic clearance was reduced as a result of suppressed excretion of urea and potassium (from 2.33 +/- 0.21 to 1.61 +/- 0.17 ml X min-1, P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)     

Renal regulation of the excretion of urea in fasting camels

Experiments were performed with young two-humped camels exposed to 36-hour starvation with free access to water. The renal functions were measured by the standard clearance method. In spite of the administration of 20 micrograms DDAVP, a higher urine flow rate was recorded in the camels subjected to control measurements (feed intake) than in the fasting period (1.45 +/- 0.06 vs. 0.96 +/- 0.06 ml . min-1, P less than less than 0.001). On the second day of fasting the camels had a significantly reduced glomerular filtration rate (GFR 317.5 +/- 23.2 vs. 170.2 +/- 17.4 ml . min-1, P less than 0.001), urea output (700.5 +/- 62.9 vs. 352.2 +/- 64.7 mumol . min-1, P less than 0.005), and fractional excretion of urea (26.9 +/- 2.8 vs. 17.9 +/- 1.7%, P less than 0.01), whereas their tubular resorption. of urea (Reab urea/GFR) increased (6.28 +/- 0.61 vs. 9.12 +/- 0.82 mumol . ml-1, P less than 0.02). No significant difference was found in the concentration of urea in plasma in the fed camels and in fasting camels (8.55 +/- 0.64 vs. 11.18 +/- 1.09 mmol . l-1, N. S.). The creatinine inulin clearance ratio (C creat/Cin) was 0.92 +/- 0.07 when the animals were fed and 1.17 +/- 0.05 when the animals starved (P less than 0.001); this suggests that the clearance of endogenous creatinine is not suitable for GFR measurement in camels under different conditions of nutrition. The kidneys of camels regulate the excretion of urea during short-time fasting mainly through the reduction of glomerular filtration rate and just partly through an increased tubular resorption.     

Changes in the renal handling of urea in sheep on a low protein diet exposed to saline drinking water

Previous trials have demonstrated that sheep on a low protein diet and free access to water, and sheep dosed with boluses of NaCl intraruminally also with free access to water, showed decreases in urea loss via the urine compared to control animals. We monitored urea excretion in sheep on a relatively poor protein diet when they were exposed to saline drinking water, i.e. they were unable to vary their intake of NaCl:water. Sheep on isotonic saline drinking water (phase 3) excreted significantly more urea via the urine (284 mM/day) compared to phase 1 when they were on non-saline drinking water (urea excretion = 230 mM/day) and phase 2 when they were on half isotonic saline drinking water (urea excretion = 244 mM/day). This finding was explained by the high glomerular filtration rate (GFR) 91.9 l/day, compared to 82.4 l/day (phase 1) and 77.9 l/day (phase 2), together with a significantly raised fractional excretion of urea (FEurea) (51.1 %) during this phase, and was in spite of the significantly lower plasma concentrations of urea in phase 3 compared to phase 1. The FEurea probably results from the osmotic diuresis caused by the salt. There were indications of a raised plasma antidiuretic hormone (ADH) concentration and this would have opposed urea loss, as ADH promotes urea reabsorption. However, this ADH effect was probably counteracted to some extent by a low plasma angiotensin II concentration, for which again there were indications, inhibiting urea reabsorption during the phases of salt loading. As atrial natriuretic peptide both increases GFR and decrease sodium reabsorption from the tubule, it was probably instrumental in causing the increase in GFR and the increase in the fractional excretion of sodium (FE(Na)).     

Consumption and ruminating behavior in sheep. 3. Experiments on infertile female sheep of different breeds with reference to feed type and feeding duration

Ewes of the breeds merino fattening sheep, Stavropol merino and fertility hybrid were studied as to their consumption and ruminating behaviour after receiving a pelleted straw-concentrate mixture, maize silage and wilted silaged grass. During the feeding periods of 2 X 45 min or 2 X 180 min/d unlimited rations were available to the animals. With 86 min/d the sheep used the short feeding period nearly completely for feed intake. In the longer feeding period the sheep consumed 18% more feed in 161 min/d, ate more slowly, however, and ruminated somewhat less. In comparison with the straw-concentrate mixture, the silage rations were ruminated for shorter periods and less effectively, the number of ruminating movements per day and cycle was reduced, the breaks between bites became longer. The wilted grass silage stimulated ruminating even less than chopped maize silage. There were significant differences between the breeds in the ruminating frequency, which affected the number of ruminating movements per day and cycle.     

4个绵羊品种MHC-DRB3基因外显子2的多态性分析

采用PCR-RFLP方法分析4个绵羊品种（阿勒泰羊、中国美利奴肉用多胎品系、湖羊和陶塞特羊）MHC-DRB3基因第2外显子的多态性，并进行聚类分析以及基因杂合度和多态信息含量的计算。结果表明：在绵羊MHC-DRB3基因第2外显子第122、154、168、220和241 bp碱基处表现出多态性；χ2适合性检验结果表明，4个绵羊群体MHC-DRB3基因的第2外显子的PstⅠ酶切位点达到了Hardy-Weinberg平衡状态，TaqⅠ和HaeⅢ酶切位点多态性均未达到Hardy-Weinberg平衡状态；4个绵羊群体基因杂合度和多态信息含量值分别在0.693～0.774和0.662～0.738之间，表明4个绵羊品种具有丰富的遗传多样性；聚类结果表明，中国美利奴肉用多胎羊和湖羊亲缘关系最近，阿勒泰羊和陶塞特羊关系较远，与实际选育过程一致，MHC-DRB3多态性可作为绵羊育种标记进一步研究。     

Serologic survey of prevalence of ovine progressive pneumonia in Idaho range sheep.

Blood samples from 2,310 mature sheep in 3 Idaho range flocks were examined by agar gel immunodiffusion to determine the prevalence of ovine progressive pneumonia. The prevalence ranged from 58% for all ages combined in one flock to 90% of cull ewes in another flock. Age-specific prevalence rates increased from 16% in yearlings to 83% in ewes greater than or equal to 7 years old. Rambouillet sheep had a significantly (P less than 0.01) lower prevalence than sheep of 5 other breeds, whereas one-half Finnsheep crosses had a significantly (P less than 0.01) higher prevalence than sheep of other breeds. Within breed and age, there was no significant difference in reproductive performance between seropositive and seronegative ewes.     

Biochemical and histological changes in the hypothalamus in hormone-stimulated sheep]

The effects were investigated of a hormonal preparation of serum gonadotrophin (SC) on neurosecretion, PAS-positive mucopolysaccharides and on histological changes in the third cerebral ventricle; at the same time variations were determined of catecholamine concentrations of ependyma surface in the hypothalamic regions that control directly reproductive functions in ewes of the Merino and Wallachian breeds in the oestrus period. Ewe oestrus was synchronized by insertion of Ageline (Spofa) sponges into the vagina. A dose of 2000 IU of serum gonadotrophin (Bioveta, Ivanovice in Haná) was administered to stimulate the ewes (n = 30). Twelve ewes of the Wallachian breed, six control and six test ones, were used for radioenzymatic detection of catecholamines (Catechola test, Prague). The brains were segmented immediately after bleeding and samples were taken from the eminentia medialis, area preoptica and corpus mamillare pursuant to the stereotactic configuration of the sheep hypothalamus (Welento et al., 1968). The brains of ten ewes of the Merino breed, four control and six test ones, and of eight ewes of the Wallachian breed (four control and four test ones) were used for histological treatment. For the purposes of a histological study, the brains were treated with current histological methods. The amount of neurosecretory material was assessed by light microscopy (Nakahara, 1963). Samples for the study of ependyma of the lower part of the third cerebral ventricle were examined in a scanning electron microscope. The obtained results demonstrate a statistically significant decrease by 36.4% (P less than 0.05) in epinephrin concentrations in the area preoptica of hypothalamus after SG administration (Fig. 3), in comparison with the control group. A decrease in norepinephrin concentration in the corpus mamillare (Fig. 4) was statistically significant (P less than 0.001). The dose of 2000 IU SG influenced most markedly catecholamine concentrations in the eminentia medialis (Fig. 5), where a statistically significant decrease in epinephrin and norepinephrin concentration was observed (P less than 0.01). Dopamine concentrations also decreased significantly (P less than 0.05) in the eminentia medialis (Fig. 5). Following the hormonal stimulation, a significant increase in dopamine and epinephrin concentrations was observed in the hypophysis of sheep (Fig. 6; P less than 0.05) and in the epiphysis there was a significant decrease in epinephrin and dopamine concentration (P less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)     

Merits of the fat-tailed Barbarine sheep raised in different production systems in Tunisia: digestive,productive and reproductive characteristics

Barbarine sheep is the dominant breed in Tunisia. This fat-tailed breed present in all production systems is characterised by metabolic and digestive adaptation to the contrasting environment conditions prevailing in the country (heat stress, water deprivation, salinity etc.). The fat tail (1.5 to 7 kg) is an energy reservoir that is used in periods of feed scarcity. Moreover, the rumen of this breed harbours a microflora enabling it to valorize low-quality roughages and native range vegetation. Barbarine sheep could make benefit from a wide range of local feed resources like fodder shrubs (e.g. cactus and oldman saltbushes), tannin-containing shrubs (e.g. Acacia cyanophylla) and agro-industrial by-products (e.g. olive cake, bran etc. conserved in the form of feed blocks or pellets). It has a very shallow anoestrous, the intensity of which is dependant upon nutrition conditions rather than day length as temperate breeds. Productive and reproductive performances of late pregnant–early suckling, pre-mating ewes and also rams of this breed are not affected when some alternative feed resources replace common feedstuffs which are expensive and cannot afford regularly to smallholders. In brief, the merits of the Barbarine sheep in the production systems and other main adaptive mechanisms of this breed are discussed in this paper. The prospective of Barbarine sheep husbandry in the system dynamics, climate change and the evolution of the socioeconomic context are also envisaged.     

舍饲绵羊产后56 d内乳成分变化规律研究

随着人民生活水平提高和膳食结构调整,绵羊奶必将受到人们的青睐.选取甘肃肉用绵羊新品种群、无角陶赛特和特克塞尔3个品种各8只母羊,对产后1～56 d泌乳理化性质变化进行研究,结果表明：3个品种乳成分及物理性质在第1～3 d变化最为明显,其中乳蛋白含量、非脂固形物含量和酸度3项指标呈现出前期快速下降,中期下降减缓,后期缓慢上升;乳糖指标则呈现出缓慢的前期上升,后期下降的趋势,对选取的3个品种初乳中蛋白、乳脂和可溶性固形物含量等指标对比,依次下降,乳糖含量和密度特克塞尔最高.常乳中除密度外3个品种间差异不显著（P＞0.05）.这为绵羊早期断奶和补饲提供了基础数据.     

Basal and hormone-stimulated metabolism in lambs varies with breed and diet quality

The present study investigated the effects of breed and diet quality on basal and hormone-stimulated energy metabolism in lambs. Twenty-four 7-mo-old merino (MM; n = 12) and second-cross (2X; n = 12) lambs were maintained indoors and fed ad libitum either a low-quality (7.8% crude protein [CP] and 8.1 MJ metabolizable energy [ME]/kg dry matter [DM]) or a moderate-quality (17.6% CP and 9.1 MJ ME/kg DM) diet in a crossover design. After 3 wk of feeding, lambs were injected intravenously with insulin (10 μg/kg body weight [BW]) and epinephrine (0.8 μg/kg BW) on consecutive days and blood samples were collected at -30, -15, -1, 3, 6, 10, 15, 20, 30, 45, 60, 90, and 120 min relative to time of injection. Lambs fed the low-quality diet had lower DM (P < 0.001), CP (P < 0.01), and ME (P < 0.001) intakes than lambs fed the moderate-quality diet. Baseline nonesterified fatty acid (NEFA) concentrations were higher (P < 0.001) in lambs fed a low-quality diet than in those fed a moderate-quality diet but there were no breed differences. Second-cross lambs had higher basal plasma concentrations of glucose (P < 0.001), lactate (P < 0.001), and cortisol (P < 0.02) than the MM lambs, although there was no effect of diet on any of these plasma variables. Insulin injection caused a rapid hypoglycemic response in all lambs but the response was more pronounced (P < 0.01) in MM lambs compared with 2X lambs. The cortisol response to insulin was twice as great (P < 0.05) in MM lambs compared with 2X lambs. There was a rebound in plasma NEFA concentrations after approximately 30 min postinjection that was most pronounced (P < 0.01) in MM lambs. Epinephrine injection caused a rapid increase in plasma NEFA, which tended to be lower in lambs fed the moderate-quality diet (P = 0.07) than in those fed the low-quality diet, but did not differ between breeds. Epinephrine injection caused rapid hyperglycemia, with the response being lower (P < 0.006) in lambs fed the moderate-quality diet compared with those fed the low-quality diet and greater (P < 0.050) in 2X than in MM lambs. Epinephrine injection caused a rapid increase in plasma lactate that tended to be greater (P = 0.07) in 2X lambs compared with MM lambs. The present study demonstrated clear breed differences in basal and hormone-stimulated metabolism, such that the 2X lambs appeared to be less sensitive to insulin and more sensitive to epinephrine than the MM lambs. These metabolic differences may be related to the fundamental differences in physiology that are associated with meat and wool production from 2X and MM breeds, respectively. They may also be related to adaptation of the MM breed to harsh environments through the ability of the body to metabolize fat resources, which are an efficient source of energy for survival.     

Allelic polymorphism in the second exon of Ovar-DRB1 in fat-tailed sheep

Ovar-DRB1 is one of the most important response genes in the major histocompatibility complex (MHC) class II region of sheep. Gene polymorphism in the second exon of Ovar-DRB1 in three different Iranian fat-tailed sheep breeds (Lori-Bakhtiari, Shaul and Zandi) was analyzed by either restriction fragment length polymorphisms (RFLP) or direct sequencing. A total of 92 Lori-Bakhtiari, 40 Shaul, and 47 Zandi sheep were examined. PCR-RFLP identified 17 genotypes in Lori-Bakhtiari sheep, 12 in Shaul sheep and 11 in Zandi sheep. Collectively, 24 different genotypes could be found for Iranian fat-tailed sheep. Using direct sequencing, seven new sequences in exon 2 of the Ovar-DRB1 gene were identified. Generalized linear modeling with a multinomial error structure showed that the sheep populations had significantly different allele frequencies.     

Lactational variation and relationship to postnatal growth of insulin-like growth factor-I in mammary secretions from genetically diverse sows

Mammary secretions obtained from four groups of sows at parturition and on days 7, 14 and 21 of lactation were defatted and assayed for total protein and insulin-like growth factor-I (IGF-I). Sows (n = 57) represented two breeds (Landrace and Duroc) and two genetic lines (selected for differences in sow productivity index, SPI) within each breed. Colostrum of Duroc sows was 4-6 fold and 30-60 fold greater in protein (P less than .001) and IGF-I (P less than .001) concentrations, respectively, than the corresponding day 7 milk from these sows. In contrast, the colostrum of Landrace sows was 2-3 fold and 30-50 fold greater in protein (P less than .001) and IGF-I (P less than .001) concentrations, respectively, than the corresponding day 7 milk. The IGF-I content in milk from Duroc sows did not differ among days 7, 14 and 21 of lactation, whereas the IGF-I content of day 7 milk from Landrace sows exceeded those for the corresponding 14 day and 21 day secretion (P less than .05). IGF-I concentration in days 14 and 21 milk was higher in Duroc (P less than .001 respectively) than Landrace sows. No significant differences in total protein or IGF-I content of mammary secretions were observed between the selected and control lines within each breed.(ABSTRACT TRUNCATED AT 250 WORDS)     

青海省绵羊品种与引进品种先天性免疫研究

为研究青海本地绵羊品种与引进品种的先天性免疫水平和品种特性,本研究选取青海省不同海拔地区的2个本地品种（欧拉羊、白藏羊）和1个引进品种（无角道赛特羊）共186只绵羊,采集新鲜血样,进行血常规检测（白细胞数（WBC）、红细胞数（RBC）、平均红细胞血红蛋白（HGB）、红细胞压积（HCT）、平均红细胞体积（MCV）、平均红细胞血红蛋白浓度（MCH）、血红蛋白浓度（MCHC）、血小板（PLT）、红细胞分布宽度（RDW-CV）、淋巴细胞百分比（LYM%））;制备血清,用绵羊ELISA试剂盒测定白介素-1（IL-1）、白介素-2（IL-2）、白介素-6（IL-6）、白介素-18（IL-18）、γ-干扰素（IFN-γ）、免疫球蛋白G （IgG）和主要组织相容性复合体（MHC）等免疫指标;分别以品种和品种来源地为因变量对检测结果进行比较分析。结果发现,以品种为因变量,无角道赛特羊的免疫水平最高,白藏羊的抗病性稍高于欧拉羊;以品种来源地为因变量时,本地绵羊品种的先天性免疫水平低于引进绵羊品种,对疾病的抵抗力较弱,除MCH、MCHC和RDW-CV外,无角道赛特羊在血液生化水平上均高于青海本地品种,说明无角道赛特羊是具有高抗病能力的优良品种。本试验为不同绵羊品种机体先天性免疫水平的研究提供了参考数据,对青海藏羊的选育工作和品种改良具有指导意义。     

Intron 1 of the interferon gamma gene: Its role in nematode resistance in Suffolk and Texel sheep breeds

Genetic variation at intron 1 of the interferon gamma gene has recently been associated with variation in faecal egg count in Romney, Merino and Soay breeds of sheep. The Texel breed is more resistant to gastrointestinal nematode infection than the Suffolk breed, based on faecal egg count. Hence, the objective of this experiment was to characterise the polymorphisms of intron 1 of the interferon gammagene in Suffolk and Texel sheep, and to determine if the characterised haplotype variants were associated with faecal egg count variation in these breeds. Intron 1 haplotypes and faecal egg measurements were determined for Suffolks (n=113) and Texels (n=135). Four haplotypes were identified in Suffolks (A, B, C and D), two haplotypes as previously described, and two previously unknown haplotypes. However, there was no association between interferon gamma intron 1 haplotype and faecal egg count in Suffolks. In contrast, two previously identified haplotypes (A and B) were present in the Texel breed, and the B haplotype was associated with resistance to nematode infection (P=0.02). These results suggest that intron 1 of the interferon gamma gene has an important role in resistance to nematode infection in the Texel breed.     

The effect of age, weight and the breed of heifer on the concentration of thyroxine during insemination

We determined the thyroxine (T4) concentration in 63 heifers on 0th (day of insemination), 6th and 21st day after first and in repeat-breeder cows after second and third insemination in relation with the breed, age and weight of animals. The examination was carried out with a feed ration balanced according to the Czechoslovak State Standard CSN 46 7070, with all-the-year-round housing, with keeping the uniform time of insemination (8.00--9.00 a. m.) as well as the time of blood sampling (10.00--12.00 a. m.). The animals were inseminated from August to November. The average T4 concentrations, with a successful insemination, fluctuated on 0th day after first, second and third insemination at levels of 56.15 +/- 13.6; 84.6 +/- 10.66 and 89.75 +/- 13.62 nmol X l-1 of serum. As the results show, the lowest T4 concentrations (P less than 0.001; P less than 0.001) on 0th day were recorded in animals becoming pregnant in first insemination. The comparison with non-pregnant animals did not show any statistically significant difference in T4 concentrations. On 0th day of the second insemination, the T4 concentrations in pregnant animals were higher (P less than 0.01) as compared with non-pregnant. On 6th and 21st day after successful first insemination the T4 content increased significantly (P less than 0.001). After second and third successful insemination we recorded in T4 concentrations a moderate decrease on 6th day (P less than 0.01 for third insemination), with insignificant increase on 21st day.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intron 1 of the interferon γ gene: Its role in nematode resistance in Suffolk and Texel sheep breeds

Genetic variation at intron 1 of the interferon gamma gene has recently been associated with variation in faecal egg count in Romney, Merino and Soay breeds of sheep. The Texel breed is more resistant to gastrointestinal nematode infection than the Suffolk breed, based on faecal egg count. Hence, the objective of this experiment was to characterise the polymorphisms of intron 1 of the interferon gammagene in Suffolk and Texel sheep, and to determine if the characterised haplotype variants were associated with faecal egg count variation in these breeds. Intron 1 haplotypes and faecal egg measurements were determined for Suffolks (n=113) and Texels (n=135). Four haplotypes were identified in Suffolks (A, B, C and D), two haplotypes as previously described, and two previously unknown haplotypes. However, there was no association between interferon gamma intron 1 haplotype and faecal egg count in Suffolks. In contrast, two previously identified haplotypes (A and B) were present in the Texel breed, and the B haplotype was associated with resistance to nematode infection (P=0.02). These results suggest that intron 1 of the interferon gamma gene has an important role in resistance to nematode infection in the Texel breed.     

Effect of nitrogen intake on nitrogen recycling and urea transporter abundance in lambs

Urea recycling in ruminants has been studied extensively in the past, but the mechanisms regulating the amount of urea recycled or excreted remain obscure. To elucidate the role of urea transporters (UT) in N recycling, nine Dorset-Finn ewe lambs (20.8 +/- 0.8 kg) were fed diets containing 15.5, 28.4, and 41.3 g of N/kg of DM for 25 d. Nitrogen balance and urea N kinetics were measured during the last 3 d of the period. Animals were then slaughtered and mucosa samples from the rumen, duodenum, ileum, and cecum, as well as kidney medulla and liver, were collected. Increasing N intake tended to increase N balance quadratically (1.5, 5.1, and 4.4 +/- 0.86 g of N/d, P < 0.09), and linearly increased urinary N excretion (2.4, 10, and 16.5 +/- 0.86 g N/d, P < 0.001) and plasma urea N concentration (4.3, 20.3, and 28.4 +/- 2.62 mg of urea N/dL, P < 0.001), but did not affect fecal N excretion (5.0 +/- 0.5 g of N/d; P < 0.94). Urea N production (2.4, 11.8, and 19.2 +/- 0.83 g of N/d; P < 0.001) and urinary urea N excretion (0.7, 7.0, and 13.4 +/- 0.73 g N/d; P < 0.001) increased linearly with N intake, as well as with the urea N recycled to the gastrointestinal tract (1.8, 4.8, and 5.8 +/- 0.40 g of N/d, P < 0.001). No changes due to N intake were observed for creatinine excretion (518 +/- 82.4 mg/d; P < 0.69) and clearance (46 +/- 10.7 mL/min; P < 0.56), but urea N clearance increased linearly with N intake (14.9, 24.4, and 34.9 +/- 5.9 mL/min; P < 0.04). Urea N reabsorption by the kidney tended to decrease (66.3, 38.5, 29.1 +/- 12.6%; P < 0.06) with increasing N content of the diet. Increasing the level of N intake increased linearly the weight of the liver as a proportion of BW (1.73, 1.88, and 2.22 +/- 0.15%, P < 0.03) but only tended to increase the weight of the kidneys (0.36, 0.37, and 0.50 +/- 0.05%, P < 0.08). Urea transporter B was present in all the tissues analyzed, but UT-A was detected only in kidney medulla, liver, and duodenum. Among animals on the three diets, no differences (P > 0.10) in UT abundance, quantified by densitometry, were found. Ruminal-wall urease activity decreased linearly (P < 0.02) with increasing level of N intake. Urease activity in duodenal, ileal, and cecal mucosa did not differ from zero (P > 0.10) in lambs on the high-protein diet. In the present experiment, urea transporter abundance in the kidney medulla and the gastrointestinal tract did not reflect the increase in urea-N reabsorption by the kidney and transferred into the gut.     

Manipulation of nitrogen digestion by sheep using defaunation and various nitrogen supplementation regimens

Five ruminally, duodenally, and ileally cannulated sheep (average BW 62 kg) were fed 65% roughage: 35% concentrate diets (CP = 15%) in a 5 x 5 Latin square design to study the applicability of using a combination of defaunation with N supplements (soybean meal [SBM], corn gluten meal [CGM], blood meal [BM], urea, and casein) with different extents of ruminal degradation to manipulate microbial protein synthesis and amount of ruminal escape protein. Diets were fed twice daily (1,759 g DM/d). Defaunation was accomplished with 30-ml doses of alkanate 3SL3 (active ingredient: sodium lauryl diethoxy sulfate)/sheep daily for 3 d with 2 d of fasting. Treatment 1 (control) involved feeding faunated sheep a diet in which the supplemental N (45% of total dietary N) was 67% SBM N and 33% urea N. Treatment 2 involved feeding defaunated sheep the same diet as the control. Treatments 3, 4, and 5 involved feeding defaunated sheep diets in which the supplemental N source was either 67% CGM-BM (1:1 N ratio) N:33% urea N, or 33% CGM-BM N:67% urea N or 33% CGM-BM N:33% urea N:33% casein N, respectively. Compared with the faunated control, defaunation decreased (P less than .05) ruminal ammonia concentration (19 vs 26 mg/dl) and increased (P less than .05) CP flow to the duodenum (253 vs 214 g/d) due to a trend for increases in both bacterial (BCP) and nonbacterial (NBCP) CP flows.(ABSTRACT TRUNCATED AT 250 WORDS)     

不同品种绵羊和山羊主要先天性免疫指标的比较

对4个山羊品种和4个绵羊品种的7项主要先天性免疫学指标进行了检测并比较。对动物进行颈静脉采血,制备血清,用ELISA试剂盒测定IL-1、IL-2、IL-6、IL-18、IFN-γ、NK细胞、血清溶菌酶。利用生物统计学的方法和原理,以品种和品种来源地为应变量对检测结果进行比较分析。结果表明,山羊当地品种的NK和LYS高于引进品种（P〈0.05）;绵羊引进品种的IL-1、IL-2、IL-6、IL-18、IFN-γ、NK、LYS均明显高于地方品种（P〈0.01）。在不同品种之间,莱芜黑山羊NK和LYS水平高于崂山奶山羊、波尔山羊和鲁波山羊,萨福克羊的IL-1、IL-6、IL-18、IFN-γ、LYS水平最高且差异极显著（P〈0.01）。小尾寒羊IL-18、IFN-γ水平最低且差异极显著（P〈0.01）。说明不同种群绵羊、山羊的先天性免疫水平存在显著差异,为以后抗病育种提供合理的试验数据。     

A longitudinal study on growth and growth variables in dogs of four large breeds raised in domestic environments

The main objective of this study was to describe the growth patterns of 4 large dog breeds [Newfoundland (NF), Labrador retriever (LR), Leonberger (LEO), and Irish wolfhound (IW)] raised in domestic environments and concomitant changes in 2 growth-related clinical variables: total serum alkaline phosphatase (ALP) and the circumference of the distal radius and ulna (CDRU). The second objective was to investigate whether these measurements were affected by a range of independent variables like age, sex, litter number, and birth weight. Seven hundred dogs were included in the study, and BW data, separated by breed and sex, were fitted to the Gompertz function. Birth weight, adjusted for litter number, differed significantly between sexes for 3 breeds (LEO, P = 0.004; NF, P = 0.02; LR, P = 0.009) and approached significance for IW (P = 0.07). Estimated mean BW increased rapidly during the first 100 d after birth in all 4 breeds, then plateaued, with maturity being reached between 351 (female LR) and 413 d (male NF). Estimated mature BW ranged from 30.8 kg for the female LR up to 65.7 kg for the male IW. Weight gain, as expressed by the derivative of the Gompertz function, reached its peak in the smallest breed (LR) at the youngest age, 89 d for the females and 95 d for males. Log-transformed BW was significantly related to age, breed, and sex, and the age x sex and age x breed interactions. Within breeds, age, birth weight, and litter number had a significant effect on log-transformed BW. The estimated average CDRU increased from 90 d of age toward a peak at 180 d. Thereafter, CDRU declined and stabilized at about 1 yr of age. The estimated total ALP concentrations decreased from 90 to 360 d of age, after which they stabilized, at mean concentrations varying among breeds from 98 to 131 IU/L. Maximum least squares mean total ALP concentrations were found at 3 mo of age in all breeds, with the greatest least squares mean concentration in the IW breed (713 IU/L). In a mixed model analysis of the complete data set, total ALP was affected (P < 0.001) by age, breed, and the interaction of age x breed. This study described the main factors influencing growth and provided reference data for other studies, including those related to nutrition and disorders of growth.