Body status and blood metabolites profiles during resumption of postpartum ovarian activity in yak (Poephagus grunniens)

We examined the changes in body weight (BW), back-fat thickness (BFT) and blood metabolites in relation to postpartum (PP) ovarian activity status in twenty female yaks raised under semi-intensive system. BFT and ovarian activities, like follicle development, ovulation (OV) and corpus luteum (CL) development, were monitored from 4 to 15 weeks (wk) PP using ultrasonography. Resumption of ovarian activity was confirmed with ovulation of dominant follicle (DF) and subsequent CL development, and >1 ng/ml progesterone concentration in blood plasma sample after 1week of ovulation. Yaks were further classified as cyclic (with CL), acyclic (without CL), and cystic (with >25 mm follicular cyst; FC). Within 20 weeks PP, 60% yaks resumed cyclic ovarian activity, while 25% failed to initiate cycling activity, and 15% developed follicular cysts. In all categories of yak, BW gradually decreased (p < .05) till nadir; however, nadir reached earlier (p < .05) in acyclic yaks. BFT differed (p < .05) among the yak groups, but it tended to be higher in cyclic yaks as compared to acyclic and cystic. No difference (p > .05) in non-esterified fatty acids (NEFA) values was found among the different categories of yaks, whereas, beta-hydroxy butyrate (BHB) levels were higher in cystic animals as compared to acyclic and cyclic. Blood glucose levels decreased in all yaks during initial 2 weeks after calving. Our findings suggest that yaks with low BW, BFT and glucose levels, and higher BHB values were at risk of delayed resumption of ovarian activity and concomitant development of follicular cysts.     

Adding heat‐treated rapeseed to the diet of yak improves growth performance and tenderness and nutritional quality of the meat

Heat‐treated rapeseed was supplemented to indoor fed yaks in winter to test the effect on dry matter intake (DMI), body mass change, and meat quality. Sixteen 3‐year‐old yak steers (124 ± 15.3 kg) were divided randomly into two groups and were offered either heat‐treated rapeseed (HTR) or rapeseed meal (CONT). The yaks were allowed 14 days for adjustment and measurements were made over 120 d. There was no difference in DMI between groups (p = 0.67), but average daily gain tended to be higher (p < 0.056) and feed to gain ratio tended to be lower (p = 0.050) in HTR than in CONT yaks. Meat from HTR yaks was more tender (p = 0.006), had higher intramuscular fat (p = 0.013), and had lower cholesterol content (p = 0.009) than from CONT yaks. In addition, the atherogenic index was lower (0.37 vs. 0.43; p = 0.049), the PUFA:SFA ratio was higher (0.55 vs. 0.37; p = 0.049), and the n‐6:n‐3 (n‐6 PUFA to n‐3 PUFA) ratio was lower (2.76 vs. 4.78; p = 0.003) in HTR than in CONT yaks, which all favoured the HTR yaks. Meat from HTR yaks met human health standards of a PUFA:SFA ratio of above 0.4 and n‐6:n‐3 ratio of less than 4, whereas meat from CONT yaks just missed these standards.     

Comparative nutrient utilization,growth, and rumen enzyme profile of mithun (Bos frontalis) and Tho-tho cattle (Bos indicus) fed on tree-leaves-based ration

A study was conducted to compare the nutrient utilization, growth, and rumen enzyme profile of mithun (Bos frontalis) and Tho-tho cattle (Bos indicus) reared in the same feeding and managemental conditions. For the purpose, male mithun (n = 8) and male Tho-tho cattle (n = 8) of 1.5 years age, selected from the farm of National Research Centre on Mithun, Nagaland, India, were fed on mixed-tree-leaves-based ration as per the requirement of NRC (2001) for cattle for 12 months. Average daily gain (ADG), average dry matter intake (DMI), and feed conversion ratio (FCR) for all animals were recorded. A metabolic trial was conducted at 6 months of the experiment to assess the digestibility coefficient of different nutrients and nutritive value of ration. At 12 months of the experiment, rumen liquor was collected from all animals and analyzed for rumen enzyme profiles, viz., carboxymethylcellulase, xylanase, α-amylase, β-glucosidase, α-glucosidase, urease, and protease. It was found that ADG (507.8 g vs 392.8 g), DM intake (6.59 vs 5.85 kg/day) and DMI/W^0.75 (98.75 g vs 91.00 g/day), crude protein intake (780 vs 700 g/day), and total digestible nutrient intake (3.65 vs 3.32 kg/day) were higher (p < 0.05) in mithun than cattle. The nitrogen balance was higher and FCR was better (p < 0.05) in mithun compared with cattle. The digestibility coefficient of different nutrients was similar (p > 0.05) between the species. The microbial enzyme profiles of mithun and cattle were not different (p > 0.05). The better growth performance of mithun than cattle as found in the present study clearly indicates that the mithun has higher genetic potential for growth than Tho-tho cattle of north-eastern hilly region of India.     

Effects of isovalerate on ruminal fermentation,urinary excretion of purine derivatives and digestibility in steers

The objective of this study was to evaluate the effects of isovalerate supplementation on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in the total tract of steers. Eight ruminally cannulated Simmental steers were used in a replicated 4 × 4 Latin square experiment. The treatments were: control (without isovalerate), low isovalerate (LIV), medium isovalerate (MIV) and high isovalerate (HIV) dosage of isovalerate at 100, 200 and 300 mg isovalerate per kg dry matter (DM) intake respectively. Diets consisted of corn stover and concentrate (60/40, DM basis). Dry matter intake was approximately 9 kg per day that was 90% of ad libitum intake including 5.4 kg corn stover and 3.6 kg concentrate. Ruminal pH (6.72–6.54) was linearly (p < 0.03) reduced, whereas total volatile fatty acid concentration (64.6–74.7 mmol/l) was linearly (p < 0.01) and quadratically (p < 0.01) increased with increasing isovalerate supplementation. Ratio of acetate to propionate increased linearly (p < 0.01) from 2.78 to 3.39 as isovalerate supplementation increased because of the increase in acetate production and decrease in propionate production. In situ ruminal degradation of amylase‐treated neutral detergent fibre (aNDF) of corn stover was improved, but crude protein (CP) degradability of soybean meal decreased with increasing isovalerate supplementation. Urinary excretion of purine derivatives was quadratically (p < 0.01) changed by altering isovalerate supplementation (50.5, 54.3, 58.9 and 55.2 mmol/day for control, LIV, MIV and HIV, respectively). Similarly, digestibilities of organic matter, aNDF and CP in the total tract were linearly and quadratically increased with increasing isovalerate supplementation. The results of this study indicate that supplementation of diet with isovalerate improved ruminal fermentation and feed digestion in beef cattle. It was suggested that the isovalerate stimulated the digestive micro‐organisms or enzymes in a dose‐dependent manner.     

Ruminal fermentation,microbial growth and amino acid flow in single‐flow continuous culture fermenters fed a diet containing olive leaves

Six single‐flow continuous culture fermenters were used to determine fermentation profile, microbial growth and amino acid (AA) flow promoted by olive leaves supplemented with barley grains and faba beans (OLSUP), and alfalfa hay (AH). Two incubation runs were carried out with three fermenters inoculated with ruminal fluid from wethers and three from goats. The inoculum source did not affect (p = 0.059 to 0.980) any of the parameters. Daily volatile fatty acid (VFA) production and carbohydrate digestibility were greater (p = 0.009 and 0.024, respectively) for AH, therefore the pH values were lower (p = 0.015) than for OLSUP. Acetate was greater (p < 0.001) and isobutyrate, isovalerate and caproate lower (p < 0.001 to 0.006) for AH with greater acetate/propionate (p = 0.014) and ‘VFA/digested carbohydrate’ (p = 0.026) ratios. Daily microbial N flow and efficiency were greater (p = 0.016 and p = 0.041) for diet AH. Individual AA flows were greater (p < 0.001 to 0.016) for AH, but microbial essential AA proportion was greater for OLSUP (p = 0.015). The results indicate that OLSUP promoted lower bacterial growth and AA flow than AH, which could have been partially due to a limitation of N availability to ruminal microbes.     

Effects of direct exposure to cold weather under grazing in winter on the physiological,immunological, and behavioral conditions of Japanese Black beef cattle in central Japan

This study aimed to reveal the effects of direct exposure to cold weather under grazing in winter (GW) on the health of Japanese Black beef cattle, as assessed using physiological, immunological, and behavioral parameters. Ten Japanese Black beef cattle (328 ± 45 kg, 7.6 ± 3.4 years of age) were used in this experiment. In winter, five of the 10 cattle grazed for 2 months in a 1.8 ha pasture (GW), and the remaining cattle were fed under confined conditions with tethering (control [CT]). The two groups were fed similar feed during the experiment, except for the grazing forage. Blood samples were collected approximately every 2 weeks. The numbers of neutrophils and monocytes and antioxidant enzyme activity were higher in the GW group than in the CT group (p < 0.05). The proportions of CD4‐single‐positive cells were lower in GW cattle than in CT cattle (p = 0.06). This study showed that direct exposure of beef cattle to cold weather under GW enhanced the levels of circulating neutrophils and monocytes and contributed to the kinetic homeostasis of lymphocytes but also activated antioxidant enzymes due to an increase in oxidative stress.     

The production of short chain fatty acid and colonic development in weaning piglets

Weaning process widely affects the small intestinal structure and function in piglets, while the responses of large intestine to weaning stress are still obscure. The purpose of this study was to determine the developmental changes (i.e., short chain fatty acids (SCFAs) concentrations, growth parameters, crypt‐related indices and antioxidant capacity) in colon of piglet during weaning. Forty piglets were weaned at day 21 and euthanized to collect colonic tissues and digesta samples on day 0, 1, 3, 7 and 14 post‐weaning (n = 8). Piglet growth performance was improved (p < .001) on day 7 and 14 post‐weaning. The concentrations of acetate, propionate, butyrate, valerate, isobutyrate, isovalerate and total SCFAs were higher (p < .001) during the late post‐weaning period. The mRNA abundances of SCFAs transporters were greater (p < .001) on day 7 and 14. The absolute and relative weights, absolute length and perimeter of colon were greater (p < .001) on day 7 and 14. Similarly, post‐weaning increases (p < .001) in colonic crypt depth and Ki67 positive cells numbers per crypt were observed during the same period. Colonic crypt fission indices decreased (p < .01), while total crypt numbers increased (p < .001) on day 14 after weaning. Moreover, total SCFAs concentration was significantly associated with colonic growth parameters and Ki67 cells/crypt (p < .001). In addition, catalase content was decreased on day 3, 7, and 14, whereas, the concentrations of total superoxide dismutase (T‐SOD) and manganese‐containing superoxide dismutase (MnSOD) were higher (p < .05) on day 1 and 3 post‐weaning. These results showed that weaning process has a significant effect on colonic growth and development, which might be associated with the change of SCFAs concentrations in colon.     

The expression of hypoxia-inducible factor-1 alpha in primary reproductive organs of the female yak (Bos grunniens) at different reproductive stages

The yak (Bos grunniens) is the most important livestock animal in high-altitude regions owing to its prominent adaptability to cold conditions, nutritional deficiencies and hypoxia. The reproductive organs exhibit different histological appearances and physiological processes at different reproductive stages. Hypoxia-inducible factor-1 alpha (HIF-1α) is the regulatory subunit of HIF-1 that crucially regulates the response to hypoxia in mammalian organisms. The goal of our study was to investigate the expression and distribution of HIF-1α in the primary yak reproductive organs at different reproductive stages. Samples of the ovary, oviduct and uterus of 15 adult female yaks were collected and used in the experiment. The expression and localization of HIF-1α proteins and mRNA were investigated using quantitative real-time polymerase chain reaction (qRT-PCR), Western blot (WB) and immunohistochemistry (IHC). The results indicated that the expression of HIF-1α protein in the ovary was higher during the luteal phase than during the follicular phase and gestation period (p < .05). In the oviduct, HIF-1α protein was also more highly expressed during the luteal phase than during the follicular phase and gestation period (p < .01). However, in the uterus, the HIF-1α protein had stronger expression during the gestation period than during the follicular phase (p < .01) and luteal phase (p < .05). The expression of HIF-1α mRNA was similar to that of its protein. Immunohistochemical analysis revealed intense immunostaining of HIF-1α proteins in the follicular granulosa cells, granular luteal cells, villous epithelial cells of the oviduct, endometrial glandular epithelium and luminal epithelium, foetal villous trophoblast, and epithelia of caruncular crypts. This study showed that the expression of HIF-1α in the ovary, oviduct and uterus varies according to the stage of the reproductive cycle. This implies that HIF-1α plays an important role in regulating the stage-specific physiological function of yak reproductive organs under hypoxic environments.     

Plasma Antimullerian Hormone as a Predictor of Ovarian Antral Follicular Population in Bos indicus (Nelore) and Bos taurus (Holstein) Heifers

In Bos taurus cattle, antimullerian hormone (AMH) has been demonstrated to have a high degree of correlation with ovarian antral follicle count and the number of healthy follicles and oocytes. To document the correlation between the plasma concentration of AMH and follicular number in Bos indicus and Bos taurus heifers, Nelore (Bos indicus, n = 16) and Holstein heifers (Bos taurus, n = 16) had their ovarian follicular waves synchronized. After synchronization, ovarian antral follicular population (AFP) was evaluated three times at 60‐day (d) intervals (T‐120 d, 120 days before plasma AMH determination; T‐60 d, 60 days before; and T0, at the time of plasma AMH determination). The plasma AMH concentration was positively correlated with the number of ovarian follicles on the day of the follicular wave emergence in Bos indicus (Nelore) and Bos taurus (Holstein) heifers at each evaluation time (p < 0.05). The AFP was higher in Bos indicus (Nelore) than in Bos taurus (Holstein) heifers (p < 0.05). Similarly, the AMH concentration was higher in Bos indicus (Nelore) than in Bos taurus (Holstein) heifers (p < 0.0001). When heifers were classified as to present high or low AFP according to the mean of the AFP within each genetic group, high‐AFP heifers presented a greater (p < 0.0001) AMH concentration than low‐AFP heifers, regardless of the genetic group. In conclusion, the AFP is positively correlated with plasma AMH concentration in both Bos indicus (Nelore) and Bos taurus (Holstein) heifers. Furthermore, Bos indicus (Nelore) heifers presented both greater plasma AMH concentrations and AFP than Bos taurus (Holstein) heifers.     

Effects of plant extracts from Stryphnodendron adstringens (mart.) coville,Lafoensia pacari a. st.-hil,copaifera spp., and Pterodon emarginatus Vogel on in vitro rumen fermentation

The effects of doses CTL (0 mg), 30, 300 and 3000 mg/L of extracts from Stryphnodendron adstringens (Mart.) Coville (SA), Lafoensia pacari A. St.-Hil (LP), Copaifera spp. (CO) and Pterodon emarginatus Vogel (PE) on ruminal fermentation were investigated in eight experiments conducted in randomized complete block designs. The in vitro system contained four fermentation vessels. Each treatment was allocated in one vessel in each run. Incubation was run four and five times with diets 50:50 and 10:90 (roughage to concentrate ratio) respectively. Incubation vessel was the experimental unit, and each incubation run was a block. All plant extracts negatively affected DM degradation at 3000 mg/L. In diet 50:50, SA-3000 increased the molar proportion of propionate (p < 0.05), yet it decreased the concentration of fermentation products (p < 0.05); LP-300 reduced ruminal ammonia nitrogen (NH₃-N; 98 vs. 120 mg/dl for LP-300 and average of CTL and LP-30, respectively) and isobutyrate (p < 0.05); CO-300 reduced (p < 0.05) NH₃-N (98 vs. 123 mg/dl for CO-300 and average of CTL and CO-30, respectively); and P. emarginatus had no positive effects on rumen fermentation (p > 0.05). In diet 10:90, SA-300 reduced (p < 0.001) NH₃-N and total volatile fatty acids (VFA); LP-30 increased (p < 0.05) total VFA (85 vs. 63 mM for LP-30 and CTL, respectively), molar proportions of acetate and propionate, and had lower C₂:C₃ than CTL (3.6 vs. 4.3, respectively); CO-300 decreased acetate and increased propionate, reducing C₂:C₃ (p < 0.001; 2.8 vs. 3.6 for CO-300 and average of other doses, respectively); PE-30 and PE-300 reduced NH₃-N by 14% and increased total VFA by 29% compared with CTL (p < 0.05). Further in vivo investigations may consider L. pacari (LP-30), Copaifera spp. (CO-300) oleoresin and P. emarginatus oleoresin (PE-30 and PE-300) in diets with high inclusion of concentrate.     

Modulation of ruminal and intestinal fermentation by medicinal plants and zinc from different sources

Two experiments were conducted on sheep to determine the effect of dietary supplementation with zinc and a medicinal plant mixture on haematological parameters and microbial activity in the rumen and large intestine. In Experiment 1, 24 male lambs were randomly divided into four groups: One group was fed an unsupplemented basal diet (control), and three groups were fed a diet supplemented with 70 mg Zn/kg diet in the form of Zn sulphate (ZnSO₄), a Zn‐chelate of glycine hydrate (Zn‐Gly) or a Zn‐proteinate (Zn‐Pro), for five months. The ruminal content was collected separately from each lamb, and batch cultures of ruminal fluid were incubated in vitro with mixture of medicinal plants (Mix) with different roughage:concentrate ratios (800:200 and 400:600, w/w). Bioactive compounds in Mix were quantified by UPLC/MS/MS. In Experiment 2, four sheep were fed a diet consisting of meadow hay and barley grain (400:600, w/w), with Zn‐Gly (70 mg Zn/kg diet), Mix (10% replacement of meadow hay) or Zn‐Gly and Mix (Zn‐Gly‐Mix) as supplements in a Latin square design. Mix decreased total gas (p < 0.001) and methane (p < 0.01) production in vitro. In Experiment 1, caecal isobutyrate and isovalerate concentrations varied among the dietary treatments (p < 0.01). The isovalerate concentration of the zinc‐supplemented groups in the distal colon was higher (p < 0.001) compared with the control. In Experiment 2, the molar proportion of isobutyrate was the highest in the faeces of the sheep fed the diet with Zn‐Gly‐Mix (p < 0.01). The plasma zinc concentration was higher in the groups fed a diet supplemented with zinc (p < 0.001). The haematological profile and antioxidant status did not differ between the dietary groups (p > 0.05). The diets containing medicinal plants and organic zinc thus helped to modulate the characteristics of fermentation in ruminants.     

Glycerine as a feed supplement for beef and dairy cattle: A meta-analysis on performance,rumen fermentation,blood metabolites and product characteristics

This study aimed to comprehensively evaluate the effects of glycerine supplementation at various concentrations on performance, rumen fermentation, blood metabolites and product characteristics of beef and dairy cattle in vivo by using a quantitative meta-analysis approach. Meta-analysis was performed by integrating a total of 52 studies from 39 articles and 182 treatments into a database. Data were constructed into an intact database and did not distinguish between beef and dairy cattle, except for the parameters of production performance and product characteristics. Data summarized were analysed by using a statistical meta-analysis that employed a fixed effect of glycerine supplementation level and a random effect of various studies for both beef and dairy cattle. Significance of an effect was stated at the probability level of p < .05, and p < .1 was considered as a tendency of significant. Results revealed that there was a linear decrease on dry matter intake (p < .01) and daily gain (p < .05) of beef cattle with the increasing levels of glycerine supplementation. Glycerine supplementation did not decrease milk production of lactating dairy cows. Molar proportion of acetate in the rumen was decreased (p < .001), whereas propionate and butyrate proportions were increased (both at p < .001) by glycerine supplementation. Generally, glycerine did not change nutrient digestibility except that it reduced fibre digestibility (p < .001). Glycerine supplementation linearly lowered triglyceride and NEFA concentrations (both at p < .05) in the blood serum, but not other blood metabolites. Glycerine tended to linearly increase (p < .1) carcass percentage in beef cattle. Increasing dietary glycerine levels decreased milk fat (p < .01) but elevated milk protein (p < .001). Glycerine tended to increase milk lactose (p < .1) by following a quadratic pattern. The proportion of MUFA was increased quadratically by glycerine supplementation (p < .05), whereas glycerine tended to decrease SFA by following a quadratic pattern (p < .1).     

Comparison of feed intake,digestion and rumen function among domestic ruminant species grazing in upland vegetation communities

This study aimed to compare feed intake, digestion, rumen fermentation parameters and bacterial community of 5 beef cows, 12 crossed ewes and 12 goats grazing together in spring–early summer on heather–gorse vegetation communities with an adjacent area of improved pasture. Organic matter intake (OMI) and digestibility (OMD) were estimated using alkane markers. Ruminal fluid samples were collected for measuring fermentation parameters, and studying the bacterial community using terminal restriction fragment length polymorphism (T‐RFLP). Spot samples of urine were taken to determine purine derivative (PD) and creatinine concentrations to estimate microbial protein synthesis in the rumen. Herbaceous species were the main dietary component in all animal species. Cattle had higher (p < 0.05) daily OMI (g/kg LW^0.75) and OMD, whereas sheep and goats showed similar values. The highest ammonia concentration was observed in sheep. Total VFA, acetate and butyrate concentrations were not influenced by animal species, while propionate concentrations in goats were 1.8 times lower (p < 0.05) than in sheep. Acetate:propionate ratio was greater (p < 0.05) in goats, whereas cattle excreted more allantoin (p < 0.05). Estimated supply of microbial N was higher in cows (p < 0.01), whereas the efficiency of microbial protein synthesis was lower (p < 0.01) in this animal species. Hierarchical clustering analysis indicated a clear effect of animal species on rumen bacterial structure. Differences among animal species were also observed in the relative frequency of several T‐RFs. Certain T‐RFs compatible with Lachnospiraceae, Proteobacteria and Clostridiales species were not found in goats, while these animals showed high relative frequencies of some fragments compatible with the Ruminococcaceae family that were not detected in sheep and cattle. Results suggest a close relationship between animals’ grazing behaviour and rumen bacterial structure and its function. Goats seem to show a greater specialization of their microbial populations to deal with the greater fibrous and tannin content of their diet.     

Health and mineral nutrition status of yaks in southern Mustang,Nepal

Biochemical values and mineral concentrations in blood plasma were investigated to evaluate the statuses of health and mineral nutrition among yaks in Mustang District, Nepal. In total, 118 plasma samples of female yaks collected in April and September/October of 2013–2015 were offered. Seventy‐four percent of yaks showed lower plasma total‐cholesterol concentrations than the lowest limit of reference range (100 mg/dL) and the values in spring (83.41 mg/dL) were lower (P < 0.05) than those in autumn (95.05 mg/dL). All the yaks had lower plasma albumin concentrations than the lowest limit of reference range (3.0 g/dL) and 66% of yaks showed lower plasma inorganic phosphorus concentrations than the critical level of phosphorus deficiency (4.5 mg/dL). Thirty‐five percent of yaks showed lower plasma calcium concentrations than the lowest limit of normal range (8 mg/dL) and the concentrations were lower in spring than in autumn (P < 0.01). Seventy‐five percent of yaks presented lower copper concentrations than the critical level (0.65 mg/L) and the concentrations were lower in spring than in autumn (P < 0.01). Since the low plasma total‐cholesterol might have indicated shortage of dry matter and energy intake, attention should be paid to the nutritional statuses of energy, phosphorus, calcium and copper in winter and early spring.     

Protein and mRNA expression of follicle‐stimulating hormone receptor and luteinizing hormone receptor during the oestrus in the yak (Bos grunniens)

Follicle‐stimulating hormone (FSH) and luteinizing hormone (LH) have a central role in follicle growth, maturation and oestrus, but no clear pathway in the seasonal oestrus of yak (Bos grunniens) has been found. To better understand the role of FSH and LH in seasonal oestrus in the yak, six yaks were slaughtered while in oestrus, and the pineal gland, hypothalamus, pituitary gland, and gonads were collected. Using real‐time PCR and immunohistochemical assays, we determined the mRNA and protein expression of the FSH and LH receptors (FSHR and LHR) in these organs. The analysis showed that the FSHR mRNA expression level was higher in the pituitary gland tissue compared with LHR (p < .01) during oestrus. By contrast, there was low expression of FSHR and LHR mRNA in the pineal gland and hypothalamus. FSHR mRNA expression was higher than that of LHR (p < .05) in the ovary, whereas LHR mRNA expression was higher than that of FSHR (p < .01) in the uterus. FSHR and LHR proteins were located in the pinealocyte, synaptic ribbon and synaptic spherules of the pineal gland and that FSH and LH interact via nerve fibres. In the hypothalamus, FSHR and LHR proteins were located in the magnocellular neurons and parvocellular neurons. FSHR and LHR proteins were localized in acidophilic cells and basophilic cells in the pituitary gland, and in surface epithelium, stromal cell and gland epithelium in the uterus. In the ovary, FSHR and LHR protein were present in the ovarian follicle. Thus, we concluded that FSHR and LHR are located in the pineal gland, hypothalamus, pituitary and gonad during oestrus in the yak. However, FSHR was mainly expressed in the pituitary gland and ovaries, whereas LHR was mainly expressed in the pituitary gland and uterus.     

牦牛夏秋季和冬季各草场牧食行为的研究

2004年8、9和11月份在青海省三角城种羊场夏、秋、冬三季牧场研究了牦牛的昼牧食行为。结果表明:牦牛在夏季草场的昼采食时间最长,平均为(337.45±39.96)min,在秋季和冬季草场的平均昼采食时间分别为(301.82±27.91)min和(304.57±12.24)min。另外,在夏季草场没有观测到牦牛的昼卧息和反刍行为。其主要原因是在夏季草场牛羊放牧压力过大,草地不能为牦牛提供足够的饲草,故牦牛延长采食时间以获取最大量的饲草,因此用于其他行为的时间相对减少。牦牛在秋冬季草场的昼反刍时间分别为(86.22±14.24)min和(53.84±13.93)min,秋季草场高于冬季草场。牦牛在秋季草场的昼站立和游走时间也高于夏季草场和冬季草场。其主要原因是由于秋季草场草产量丰富,质量较好。由于冬季草场气候寒冷,牧草枯黄,质量降低,牦牛的昼卧息时间最长。     

The Effect of increasing levels of date palm (Phoenix dactylifera L.) seed on the performance,ruminal fermentation,antioxidant status and milk fatty acid profile of Saanen dairy goats

This study was conducted to examine the effect of date palm (Phoenix dactylifera L.) seed (DPS) on the performance, ruminal fermentation, antioxidant status and milk fatty acid (FA) profile of dairy goats. Eight multiparous Saanen dairy goats, averaging 97 ± 7 days in milk (DIM) and 2150 ± 130 g of milk production, were used in a 4 × 4 replicated Latin square design. Experimental diets contained 0% (control), 6% (DPS6), 12% (DPS12) and 18% (DPS18) of DPS. Dry matter intake (DMI), milk production, and the composition and digestibility of the dry matter (DM), organic matter (OM), neutral detergent fibre (NDF) and crude protein (CP) were not affected by the diets. Adding DPS to the diet increased linearly total antioxidant capacity (TAC) in milk and blood (p < 0.05). No significant difference was found in the malondialdehyde (MDA) content in milk and blood. Superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) activities in the blood, ruminal pH, NH₃‐N, ruminal total volatile fatty acid (VFA), acetate, butyrate, isovalerate and valeric acid concentration had no significant effect among the diets. The propionate acid concentration decreased linearly as DPS was added to the diet, and DPS18 had minimum propionate acid concentration (p < 0.05). The inclusion of DPS18 to diets increased linearly the proportion of C18:0 (compared to control) as well as cis‐18:1, trans‐18:1 (compared to control and DPS6) and decreased C14:1 (compared to control) in milk fat (p < 0.05). The concentration of conjugated linoleic acid (CLA) in DPS18 was higher than other diets (p = 0.04). The results of this study implied that replacing DPS with a part of dairy goats’ ration had no negative effects on the performance of the animals and could also improve the antioxidant activity and increase the concentration of CLA in their milk.     

Effect of dietary energy on digestibilities,rumen fermentation,urinary purine derivatives and serum metabolites in Tibetan and small‐tailed Han sheep

Tibetan sheep are indigenous to the Qinghai–Tibetan Plateau, graze the grassland all year round without supplementation and are well‐adapted to the harsh conditions. Small‐tailed Han sheep were introduced to the plateau and are raised mainly in feedlots. Based on their different backgrounds, we hypothesized that the ability to cope with poor diets would be better in Tibetan than in Han sheep. To test our prediction, we examined the effect of dietary energy on apparent digestibilities, rumen fermentation, urinary purine derivatives and serum metabolites by using a 4 × 4 Latin square design in each sheep breed. Four diets were formulated to be low in crude protein (~7%) but to differ in metabolizable energy concentration. Average daily gain was greater in Tibetan than in Han sheep (p < 0.01) and increased linearly with an increase in energy intake (p < 0.001). The digestibilities of dry matter, organic matter, gross energy, and neutral and acid detergent fibres were greater in Tibetan than in Han sheep (p < 0.05). Ruminal pH was lower (p < 0.05), while volatile fatty acids (VFAs), urea‐N, ammonia‐N and soluble protein‐N concentrations were higher (p < 0.05) in Tibetan than in Han sheep. As a molar proportion of total VFA, acetate decreased (p < 0.001) with an increase in dietary energy whereas propionate and butyrate increased (p < 0.05). Urinary purine derivative excretion was greater in Tibetan than in Han sheep (p < 0.01), as was microbial nitrogen production; both parameters increased with dietary energy (p < 0.01). Serum concentrations of glucose, insulin and insulin‐like growth factor‐1 increased (p < 0.05) as energy level increased, while non‐esterified fatty acids and growth hormone decreased (p < 0.05). It was concluded that Tibetan sheep were better able to cope with low‐protein, low‐energy diets and, consequently, our prediction was supported.