N-carbamylglutamate restores nitric oxide synthesis and attenuates high altitudeinduced pulmonary hypertension in Holstein heifers ascended to high altitude

Background: High-altitude pulmonary hypertension(HAPH) is a life-threating condition for animals in high altitude,and disturbance of endothelial nitric oxide(NO) synthesis contributes to its pathogenesis. N-carbamylglutamate(NCG), which enhances arginine synthesis, promotes endogenous synthesis of NO. In this study, we determined the effects of NCG on alleviating HAPH in Holstein heifers that ascended to Tibet(Lhasa, 3,658 m).Methods: Exp. 1, 2,000 Holstein heifers were transported from low elevation(1,027 m) to Lhasa. After being exposed to hypoxia for 1 yr, Holstein heifers were assigned to a healthy group(Control, n = 6) with mean pulmonary hypertension(mPAP) < 41 mmHg, and an HAPH affected group(HAPH, n = 6) with mPAP > 49 mmHg.Lung tissues were collected to evaluate histopathological changes and the expression of endothelial nitric oxide synthase(eNOS). Exp. 2, ten healthy heifers and 10 HAPH affected heifers were supplemented with NCG(20 g/d per heifer) for 4 wk. Physiological parameters were determined and blood samples were collected on d-1 and d 28 of the feeding trial.Results: Expression of e NOS in small pulmonary arteriole intima was higher in the healthy than HAPH group(P = 0.006), whereas HAPH group had significantly thicker media and adventitia than healthy group(all P < 0.05). The mRNA of eNOS and protein level of eNOS were higher in the lungs of heifers in the healthy group than in the HAPH group(both P < 0.001), whereas endothelin-1 protein levels were higher in HAPH group than in the healthy group(P = 0.025). NCG supplementation decreased mPAP and ammonia(both P = 0.001), whereas it increased the expression of eNOS, arginine, and plasma NO(all P < 0.05).Conclusions: The expression of eNOS was decreased in Holstein heifers with HAPH. NCG supplementation decreased m PAP through the restoration of eNOS and endogenous NO synthesis.

Effect of mammary stimulation on dairy cows and heifers exposed to a lactation induction protocol

Cows (n = 21), dried off for a minimum of 45 days, and nulliparous heifers (n = 26), at ages > 18 months old, were placed on a 12-day Lactation Induction (LI) protocol. One group of animals (including both cows and heifers) received 3-minute mammary gland stimulation, along with the LI protocol. Another group, again including both cows and heifers, received no stimulation only the LI protocol This consisted of two injections of prostaglandin F2α (PGF2α;25 mg) 11 days apart, followed by subcutaneous injections of 17β-estradiol (0.1 mg/kg BW/d) and progesterone (0.25 mg/kg BW/d) beginning 1 day later and continuing for seven (7) days. After this step, all animals received another injection of PGF2α on day 8, followed by intramuscular injections of reserpine (5 mg/d) and dexamethasone (20 mg/d) on each of days 9 to 12. All animals were milked, beginning on day 13, for a period of 154 days. For all animals, the success rate for lactation induction was 78% ± 6.3% and the mean weekly milk yield was 78.2 kg. Neither value was affected by mammary stimulation. Parity did not significantly impact on the success rate but it did affect the mean weekly milk yield. Milk yield varied significantly (p < 0.001) with week, peaking during week 9. Peak milk production and persistency were 101.6 kg ± 5.9 kg and 16.9 weeks ± 2.4 weeks respectively, with neither being significantly (α = 0.05 level) affected by stimulation or by parity. However, heifers (at 8.2 weeks ± 1.0 week) tended (p = 0.1) to reach peak milk production earlier than cows (at 10.7 weeks ± 1.3). The milk produced was sold at a net profit per animal treated of $2206.31 TT. Hence, one can conclude that a Lactation Induction protocol can be a useful management tool to increase production and profitability of dairy operations in the tropics.

Heat stress on calves and heifers: a review

The current review is designed with aims to highlight the impact of heat stress(HS) on calves and heifers and to suggest methods for HS alleviation. HS occurs in animals when heat gain from environment and metabolism surpasses heat loss by radiation, convection, evaporation and conduction. Although calves and heifers are comparatively heat resistant due to less production of metabolic heat and more heat dissipation efficiency, they still suffer from HS to some degree. Dry matter intake and growth performance of calves and heifers are reduced during HS because of redistributing energy to heat regulation through a series of physiological and metabolic responses, such as elevated blood insulin and protein catabolism. Enhanced respiration rate and panting during HS accelerate the loss of CO2, resulting in altered blood acid-base chemistry and respiratory alkalosis. HS-induced alteration in rumen motility and microbiota affects the feed digestibility and rumen fermentation. Decreased luteinizing hormone, estradiol and gonadotrophins due to HS disturb the normal estrus cyclicity, depress follicular development, hence the drop in conception rate. Prenatal HS not only suppresses the embryonic development by the impaired placenta, which results in hypoxia and malnutrition, but also retards the growth, immunity and future milk production of newborn calves. Based on the above challenges, we attempted to describe the possible impacts of HS on growth, health, digestibility and reproduction of calves and heifers. Likewise, we also proposed three primary strategies for ameliorating HS consequences. Genetic development and reproductive measures, such as gene selection and embryo transfers, are more likely long-term approaches to enhance heat tolerance. While physical modification of the environment, such as shades and sprinkle systems, is the most common and easily implemented measure to alleviate HS. Additionally, nutritional management is another key approach which could help calves and heifers maintain homeostasis and prevent nutrient deficiencies because of HS.

Assessment of Negative Training on the Use of Cubicle Beds by Heifers

40 in-calf heifers were observed to examine the effect of timbers placing in passage area on their use of cubicle beds. Prior to the experiment preliminary observation was taken on these 40 heifers and they were divided into two even groups (cubicle user(or control) group versus cubicle refusal (or experimental) group by whether they properly used the cubicle beds or not. The timbers were placed in passage and feeding areas for the cubicle refusal group to force the animls to lie in the cubicle beds. The results of this experiment showed that feeding behaviour was unaffected by the presence of the timbers, but lying acitvity was about 8% higher for the experimental group, which led to a mean of almost 2 hours longer lying time over 24 h. After the timbers were removed, there was a significant decline in lying by the experimental group. The diurnal pattern of lying behaviour in cubicles indicated that the major effect on lying activity exerted by the presence of the timbers was seen during midnight to 10:00 am. Also during this times, the experimental group in the pres-ence of the timbers tended to show more lying in cubicles than control group. At the end of the experiment, 95% of the heifers were found to be correctly using the cubicle beds, and on the negative side three heifers developed a slight injury on their legs or hocks caused by the timber.

Methane Emissions from Grazing Holstein-Friesian Heifers at Different Ages Estimated Using the Sulfur Hexafluoride Tracer Technique

Although the effect of animal and diet factors on enteric methane （CH4） emissions from confined cattle has been extensively examined, less data is available regarding CH4 emissions from grazing young cattle. A study was undertaken to evaluate the effect of the physiological state of Holstein-Friesian heifers on their enteric CH4 emissions while grazing a perennial ryegrass sward. Two experiments were conducted： Experiment 1 ran from May 2011 for 11 weeks and Experiment 2 ran from August 2011 for 10 weeks. In each experiment, Holstein-Friesian heifers were divided into three treatment groups （12 animals/group） consisting of calves, yearling heifers, and in-calf heifers （average ages： 8.5, 14.5, and 20.5 months, respectively）. Methane emissions were estimated for each animal in the final week of each experiment using the sulfur hexafluoride tracer technique. Dry matter （DM） intake was estimated using the calculated metabolizable energy （ME） requirement divided by the ME concentration in the grazed grass. As expected, live weight increased with increasing animal age （P 〈 0.001）; however, there was no difference in live weight gain among the three groups in Experiment 1, although in Experiment 2, this variable decreased with increasing animal age （P 〈 0.001 ）. In Experiment 1, yearling heifers had the highest CH4 emissions （g·d^-1） and in-calf heifers produced more than calves （P 〈 0.001 ）. When expressed as CH4 emissions per unit of live weight, DM intake, and gross energy （GE） intake, yearling heifers had higher emission rates than calves and in-calf heifers （P 〈 0.001）. However, the effects on CH4 emissions were different in Experiment 2, in which CH, emissions （g·d^-1） increased linearly with increasing animal age （P 〈 0.001）, although the difference between yearling and in-calf heifers was not significant. The CH4/live weight ratio was lower in in-calf heifers than in the other two groups （P 〈 0.001 ）, while CH4 energy output as a proportion of GE intake was lower in calves than in yearling and in-calf heifers （P 〈 0.05）. All data were then pooled and used to develop prediction equations for CH4 emissions. All relationships are significant （P 〈 0.001）, with R2 values ranging from 0.630 to 0.682. These models indicate that CH4 emissions could be increased by 0.252 g.d-1 with an increase of I kg live weight or by 14.9 g·d^-1 with an increase of 1 kg·d^-1 of DM intake; or, the CH4 energy output could be increased by 0.046 MJ·d^-1 with an increase of 1 MJ·d^-1 of GE intake. These results provide an alternative approach for estimating CH4 emissions from grazine dairy heifers when actual CH, emission data are not available.

Evaluation of age, weaning weight, body condition score, and reproductive tract score in pre-selected beef heifers relative to reproductive potential

Background: Artificial insemination is a preferred breeding method for beef heifers as it advances the genetic background, produces a predictive and profitable calving season, and extends the heifer’s reproductive life span.As reproductive efficiency in heifers is key for the success of beef cattle production systems, following artificial insemination, heifers are exposed to a bull for the remainder of the breeding season. Altogether, up to 95% of heifers might become pregnant in their first breeding season. Heifers that do not become pregnant at the end of the breeding season represent an irreparable economical loss. Additionally, heifers conceiving late in the breeding season to natural service, although acceptable, poses serious losses to producers. To minimize losses due to reproductive failure, different phenotypic parameters can be assessed and utilized as selection tools. Here, we tested the hypothesis that in a group of pre-selected heifers, records of weaning weight, age at weaning, age at artificial insemination, and age of dam differ among heifers of varied reproductive outcomes during the first breeding season.Results: None of the parameters tested presented predictive ability to discriminate the heifers based on the response variable(‘pregnant to artificial insemination’, ‘pregnant to natural service’, ‘not pregnant’). Heifers categorized with body condition score = 6 and reproductive tract score ≥ 4 had the greatest proportion of pregnancy to artificial insemination(49% and 44%, respectively). Furthermore, it was notable that heifers presenting body condition score = 6 and reproductive tract score = 5 presented the greatest pregnancy rate at end of the breeding season(89%). Heifers younger than 368 d at the start of the breeding season did not become pregnant to artificial insemination. Those young heifers had 12.5% chance to become pregnant in their first breeding season,compared to 87.5% if the heifers were older than 368 days.Conclusion: Our results suggest that beef heifers with body condition score = 6 and reproductive tract score ≥ 4 are more likely to become pregnant to artificial insemination. Careful assessment should be undertaken when developing replacement heifers that will not reach 12 months of age by the beginning of the breeding season.

Association of a missense mutation in the luteinizing hormone/choriogonadotropin receptor gene (LHCGR) with superovulation traits in Chinese Holstein heifers

Background： Upon binding luteinizing hormone in the ovary, the luteinizing hormone/choriogonadotropin receptor （LHCGR） is necessary for follicular maturation and ovulation, as well as luteal function. We detected mutations in the LHCGR gene and evaluated their association with superovulation. Methods： Using polymerase chain reaction-single strand sequencing, we examined polymorphisms in LHCGR and Chinese Holstein heifers. conformation polymorphism （PCR-SSCP） and DNA the genotypes associated with superovulation traits in 127 Results： A G/T polymorphism （ss52050737） in exon 11 was significantly associated with the total number of ova and the number of transferable embryos. Conclusions： LHCGR may be a new predictor for superovulation in Chinese Holstein heifers.

Association between growth rates, age at first calving and subsequent fertility, milk production and survival in Holstein-Friesian heifers

Age at first calving (AFC) affects the profitability of dairy enterprises. This study examined the relationships between AFC and subsequent fertility, milk production and survival up to third calving in UK Holstein-Friesian heifers;Study 1 comprised 134 consecutively born heifers from the same herd (AFC 764 ± 8 days) and Study 2 contained 445 heifers born on 17 farms (AFC 796 ± 6 days). Growth rates and fertility during rearing were monitored and animals were subsequently divided into four AFC groups for analysis: <23 months, 23 - 25 months, 26 - 30 months and >30 months. The actual AFC reflected both growth rate and heifer fertility, with later calving heifers already lighter by 6 months of age. The proportion conceiving to first service was highest (93% and 84% for Studies 1 and 2, respectively) for the youngest AFC group. Fertility in the first lactation was best in cows calving at 23 - 25 months and worst in the oldest AFC group. Milk production parameters in the first and second lactations were broadly similar between AFC groups but significantly more heifers with an AFC < 26 months calved for a third time. These younger calving animals therefore achieved more days in milk over 5 years, with >44% of their days alive spent in milk production compared with only 18% - 40% in cows calving at ≥26 months. Hence cows with an AFC < 26 months produced the most milk in their first 5 years of life. These results indicate that an AFC of 0.75 kg/d up to 15 months and good heifer fertility and resulted in the best subsequent performance.

The Management and Associated Costs of Rearing Heifers on UK Dairy Farms from Weaning to Conception

Dairy heifers only start to produce a return on investment at first calving. The length of the non-productive rearing period is largely governed by farmer decisions on plane of nutrition and reproduction management. Primary data were collected from 101 dairy farms and a cost analysis workbook developed to calculate individual inputs in each of three periods to determine which management decisions and farm factors have the greatest influence on the total costs associated with rearing. This paper covers weaning until conception. Heifers were weaned at 62 d (range 42 - 112 d) and conceived by 509 d (range 365 - 700 d) giving an average weaning to conception period of 447 ± 60 d (range 253 to 630 d). The mean daily cost of rearing during this period was ￡1.65 (range ￡0.75 to ￡2.97 on different farms) giving a mean total cost of ￡745.94 per heifer (range ￡295.32 to ￡1745.85). This large variation was mostly due to the duration, which was mainly determined by age at first breeding (mean 476 days, range 365 - 700 d). The main contributors to total costs were feed (35.6%), labour (24.7%) and bedding (8.9%). The variables most strongly associated with the total costs were age at conception, calving pattern and breed. A multivariable model predicted an increase in mean cost of ￡2.26 for each extra day in age at conception. The total cost was highest in herds with all year round calving, intermediate in multi-block and lowest in spring and autumn calving herds, with Friesian x and Jersey herds having the lowest cost of rearing.

Analysis of the Management and Costs Associated with Rearing Pregnant Dairy Heifers in the UK from Conception to Calving

Good management of the pregnant heifer is crucial to ensure that she is well grown and healthy and calves down easily before joining the milking herd. This study collected primary data on all aspects of heifer management on 101 UK farms during heifer pregnancy from conception to calving including farm factors and associated costs of system inputs. A cost analysis workbook was developed to calculate the cost of rearing per heifer for each of the study farms. Associations between cost of rearing and farms factors were determined using linear regression and analysis of variance. Heifers had a mean age of conception of 509 d (range 365 - 700 d) and an age at first calving of 784 d (range 639 - 973 d). The mean total cost of rearing during pregnancy was ￡450.36 (range ￡153.11 to ￡784.00) with a mean daily cost of ￡1.64 (range ￡0.56 to ￡2.86). The inputs contributing the most to cost were feed (32.7%), labour (23.8%) and slurry disposal (11.2%). Total purchased and homegrown feed and grazing contributed between 25.5% and 65.4% of total costs with a mean contribution of 43.6%. The cost of rearing was lowest in spring calving herds and highest in all year round calving herds with intermediate values in autumn and multi block calving herds. The main variables influencing the cost were the number of days spent at grass, age at first calving, calving pattern, breed, herd size and region. Each extra day in age at first calving increased the mean cost of rearing during pregnancy by ￡0.33/d whereas every extra day at grass reduced the cost by ￡1.75/d.

Comparison of Two Different Protocols for Induction of Parturition in Heifers with or without Estradiol Benzoate

Objectives of this study were to investigate the efficacy of dexamethasone in combination with estradiol benzoate in controlled induction of parturition in heifers, especially in the subjects of retained fetal membranes and dystocia caused by fetal oversize. A total number of 100 Holstein-Friesian heifers aged 24-25 months, mean weight 450 kg and body condition score of 3-4 from a dairy herd located in the suburb of Tabriz with similar nutrition and management systems were allocated at random into two groups. Group A （Control, n = 50） heifers, after passing the minimum 270 d of pregnancy were injected with 30 mg dexamethasone IM. Group B （Treatment, n = 50） heifers with the same period of pregnancy received 30 mg dexamethasone plus 20 mg estradiol benzoate IM on the same days of pregnancy. The overall durations of initial treatments to induction of parturition were （41.50 ~ 2.65） h in group A and （37.50 ：i： 1.27） h in group B. In group A, more dystocia cases were observed than in group B. After parturition, group A showed a higher percentage of retention of fetal membranes as well as the calf mortality and dystocia compared to group B. The differences between two groups were statistically significant （P 〈 0.05）. In conclusion, our results indicate that induction of parturition by estradiol benzoate and dexamethasone together will be more effective than dexamethasone alone because of the less retention of fetal membranes, easy calving and shorter time from induction to parturition.

Preference, Feeding Behavior, and in Vitro Fermentation Characteristics of Pelleted Feeds Containing Alkaline Aqueous Lignin By-Product from Paper Processing in Holstein Heifers

The objectives of this study were to evaluate the effect of using multiple dietary inclusion rates of alkaline aqueous lignin by-product(AALB),in replacing a commercial binder,on the preference and feeding behavior of dairy heifers,and in vitro digestibility.In the experiment I,five pelleted diets including negative control(no-binder),commercial lignosulfonate binder,and 1.6%,3.2%,and 4.8%of AALB were tested.In the experiment II,five pelleted diets including negative control,positive control(2%molasses),and 1%,2.4%,and 3.8%of AALB(all combined with 2%of molasses)were tested.Feeding behavior and preference were determined for 60 min per animal per evaluation.In vitro digestibility was determined for each pelleted diet for 48 h over five incubation runs.Results from Experiment I showed animals receiving 1.6%of AALB diet showed the greatest preference(dry matter(DM),intake)and a greater number of approaches with eating than other diets.The preference was lower when animals received control or 4.8%AALB diets relative to other diets.Results from Experiment II revealed animals receiving 3.8%AALB combined with molasses showed the greatest DM intake preference over 60 min,and DM intake per approach.Diets that included 2.4%and 3.8%of AALB combined with molasses presented the greatest in vitro DM digestibility.Overall,heifers showed a greater intake when receiving pelleted diets with 1.6%AALB.Furthermore,preference,intake over 60 min,and in vitro DM digestibility,were greater in the pelleted diets that contained higher rates of AALB when combined with molasses.

The crucial role of lysine in the hepatic metabolism of growing Holstein dairy heifers as revealed by LC-MS-based untargeted metabolomics

The objective of this experiment was to evaluate the effect of supplementing rumen-protected Lys based on a Lys-deficient diet on liver metabolism in growing Holstein heifers.The experiment was conducted for 3 months with 36 Holstein heifers(initial body weight:200±9.0 kg;7-month-old).Heifers were randomly assigned to 2 diets based on corn,soybean meal,alfalfa hay,and wheat bran:control,Lysdeficient diet(LD;0.66%Lys in diet),and Lys-adequate diet(LA;1.00%Lys in diet).The results showed no difference in growth performance between the 2 groups(P>0.05).However,there was a clear trend of increasing feed conversion rate with Lys supplementation(0.05<P<0.01).The serum urea nitrogen concentration was significantly decreased,and the aspartate aminotransferase-to-alanine aminotransferase ratio was significantly decreased by Lys supplementation(P<0.05).Moreover,growing heifers fed a Lys-adequate diet had lower levels of urine nitrogen excretion and higher levels of the biological value of nitrogen(P<0.05).Metabolomic analysis revealed that 5 types of phosphatidylcholine and 3 types of ceramide were significantly increased and enriched in sphingolipid metabolism and glycero phospholipid metabolism(P<0.05).His,Leu,and Asp levels were significantly decreased in the liver following Lys supplementation(P<0.05).In conclusion,Lys supplementation may promote the synthesis of body tissue proteins,as evidenced by significantly decreased amino acids in the liver and urine N excretion,it also improves hepatic lipid metabolism by providing lipoprotein precursors.

Heifer Body Weight Gain and Reproductive Achievement in Response to Protein and Energy Supplementation While Grazing Dormant Range Forage

Heifers grazing winter range require supplemental nutrients to complement dormant forage to achieve optimal growth and performance. A study was conducted to evaluate nutritional environment and effect of different supplementation strategies for developing heifers grazing dormant winter range. Eighty-four Angus crossbred heifers were stratified by body weight at weaning, allocated to one of six replicated pastures, and randomly assigned one of three supplemental treatments: 1) 908 g/d of a control supplement providing 340 g·hd-1·d-1 of CP with 130 g of rumen undegradable protein (RUP) and 614 MJ of ME (LRUP);2) 908 g/d of a RUP supplement providing 340 g·hd-1·d-1 of CP with 170 g of RUP and 567 MJ of ME (HRUP);or 3) 1814 g/d of a protein and energy supplement providing 340 g·hd-1·d-1 of CP with 120 g of RUP + 100 g of propionate salt (NutroCalTM, Kemin Industries, Inc.) and 1222 MJ of ME (LRUP + E). Body weights were taken in November, with monthly 12 h shrunk BW from January thru April, and again in September (at time of pregnancy diagnosis). Heifer average daily gain was similar throughout the developmental period except from d125 to d159 where LRUP + E supplemented heifers had greater gains

Delaying Postpartum Supplementation in Cows Consuming Low-Quality Forage Does Not Alter Cow and Calf Productivity

Reducing the amount of supplemental feed postpartum without affecting productivity may enhance profitability of cow-calf operations. Therefore, sixteen 2-yr-old fall calving cows were used to evaluate effects of delaying postpartum supplementation on milk production, serum metabolites, and cow and calf BW change. Cows were stratified by calving date and randomly assigned to one of two treatments: 908 g/d of a 46% CP supplement beginning 5 d postpartum (Supp5, n = 7);or 908 g/d of the same supplement beginning 30 d postpartum (Supp30, n = 9). Supplements were formulated to provide 425 g/d of CP with 225 g coming from ruminally undegradable protein (RUP), and were fed twice weekly. Cows were daily fed 8.2 kg chopped sudangrass hay (5.5% CP, 74% NDF, OM basis) during lactation. Cows and calves were weighed before feeding on two consecutive days on d 0, d 30, and d 80 postpartum. Milk production and constituents were evaluated on d 90. Cow BW was not different at d 0 (P = 0.21) and 80 (P = 0.12) between treatment groups. Cows receiving supplement starting on d 5 postpartum were heavier (P = 0.04) than Supp30 cows on d 30. However, no differences (P ≥ 0.17) were found in BW change or ADG during the duration of the study. Milk production was similar (P = 0.99) for postpartum supplementation treatments. No differences (P ≥ 0.27) were observed in milk fat, lactose, protein, or solids-non-fat. However, there was a tendency (P = 0.09) for milk urea nitrogen to be greater for cows receiving supplement on d 5 than d 30 of lactation. Serum urea nitrogen was greater (P = 0.02) in cows receiving Supp5 than cows receiving Supp30. Serum non-esterified fatty acid (NEFA) and glucose concentrations were not different (P ≥ 0.40) between treatment groups. Calf BW and average daily gain (ADG) was not influenced (P ≥ 0.81) by timing of initial postpartum supplementation. These results indicate that withholding supplementation during the first 30 d postpartum may change pattern of cow BW loss without affecting net BW loss, milk production, or calf growth. Therefore, timing of postpartum supplementation can be manipulated to reduce amount of feed provided without sacrificing cow or calf productivity.

A Study of Dairy Heifer Rearing Practices from Birth to Weaning and Their Associated Costs on UK Dairy Farms

There are many inputs into the dairy replacement herd which impact not only on the cost of rearing heifers from birth to first calving, but also on their future longevity and production potential. This study determined the current cost of rearing dairy heifers in the UK through the calculation and analysis of individual costs on a subset of 102 UK dairy farms. Each farm was visited and an extensive heifer rearing questionnaire was completed. Current heifer rearing practices were recorded to provide insight into critical management decisions. A cost analysis workbook was developed to calculate the costs of inputs in the preweaning period for labour, calving, feed, housing, health treatments and vaccinations, waste storage, machinery and equipment, and utilities. The average age at weaning was 62 d. The mean cost of rearing from birth to weaning was ￡195.19 per heifer with a mean daily cost of ￡3.14 (excluding the opportunity cost of the calf). This ranged from ￡1.68 to ￡6.11 among farms, reflecting major differences in management strategies and efficiency. The highest contribution to total costs came from feed (colostrum, milk, starter and forage) at 48.5% with milk feeding making up the greatest proportion of this at 37.3%. The next major expenses were bedding and labour, contributing 12.3% and 11.2% respectively. Unsurprisingly, delaying age at weaning increased total cost by ￡3.53 per day. Total costs were on average 45% higher on organic farms than conventional due to higher feed costs and later weaning. Calving pattern also had a strong association with the total cost being lowest with spring calving, intermediate with autumn calving and highest in multi block and all year round calving herds.

Fine mapping of genomic regions associated with female fertility in Nellore beef cattle based on sequence variants from segregating sires

Background:Impaired fertility in cattle limits the efficiency of livestock production systems.Unraveling the genetic architecture of fertility traits would facilitate their improvement by selection.In this study,we characterized SNP chip haplotypes at QTL blocks then used whole-genome sequencing to fine map genomic regions associated with reproduction in a population of Nellore(Bos indicus)heifers.Methods:The dataset comprised of 1337 heifers genotyped using a GeneSeek®Genomic Profiler panel(74677 SNPs),representing the daughters from 78 sires.After performing marker quality control,64800 SNPs were retained.Haplotypes carried by each sire at six previously identified QTL on BTAs 5,14 and 18 for heifer pregnancy and BTAs 8,11 and 22 for antral follicle count were constructed using findhap software.The significance of the contrasts between the effects of every two paternally-inherited haplotype alleles were used to identify sires that were heterozygous at each QTL.Whole-genome sequencing data localized to the haplotypes from six sires and 20 other ancestors were used to identify sequence variants that were concordant with the haplotype contrasts.Enrichment analyses were applied to these variants using KEGG and MeSH libraries.Results:A total of six(BTA 5),six(BTA 14)and five(BTA 18)sires were heterozygous for heifer pregnancy QTL whereas six(BTA 8),fourteen(BTA 11),and five(BTA 22)sires were heterozygous for number of antral follicles’QTL.Due to inadequate representation of many haplotype alleles in the sequenced animals,fine mapping analysis could only be reliably performed for the QTL on BTA 5 and 14,which had 641 and 3733 concordant candidate sequence variants,respectively.The KEGG“Circadian rhythm”and“Neurotrophin signaling pathway”were significantly associated with the genes in the QTL on BTA 5 whereas 32 MeSH terms were associated with the QTL on BTA 14.Among the concordant sequence variants,0.2%and 0.3%were classified as missense variants for BTAs 5 and 14,respectively,highlighting the genes MTERF2,RTMB,ENSBTAG00000037306(miRNA),ENSBTAG00000040351,PRKDC,and RGS20.The potential causal mutations found in the present study were associated with biological processes such as oocyte maturation,embryo development,placenta development and response to reproductive hormones.Conclusions:The identification of heterozygous sires by positionally phasing SNP chip data and contrasting haplotype effects for previously detected QTL can be used for fine mapping to identify potential causal mutations and candidate genes.Genomic variants on genes MTERF2,RTBC,miRNA ENSBTAG00000037306,ENSBTAG00000040351,PRKDC,and RGS20,which are known to have influence on reproductive biological processes,were detected.

Effects of Reduced <i>in Utero</i>and Post-Weaning Nutrition on Glucose Clearance Measures and Serum Metabolites

Lowering production costs while maintaining an optimal level of production is important to producers in extensive environments. Efforts that strive to match the environment to the nutritional requirements of the grazing animal will substantially improve economic returns to the producer. Therefore, a 3-yr study was implemented that evaluated glucose clearance and serum metabolites in primiparous beef heifers (n = 48;16/yr) from two different feeding regimes. Serum metabolites and glucose clearance measures were analyzed by fitting a repeated measure mixed model using the MIXED procedure of SAS 9.4 (SAS Inst., Inc., Cary, NC). Heifers dams received adequate 1.8 (ADEQ) or marginal 1.2 (MARG) kg/d winter supplementation for approximately 80 d prior to parturition and their heifer calves were then randomly assigned to heifer development treatments that provided ad-libitum (AL) or 80% of ad-libitum (LAL) feed post weaning. Heifers that received the AL treatment during the developmental period were then assigned the 1.8 kg/d winter supplementation for life, whereas heifers that received the LAL treatment during development were assigned the 1.2 kg/d winter supplementation for life. Peak glucose concentrations in response to a bolus dose of glucose changed in magnitude between ADEQ and MARG in utero treatments and decreased further removed from parturition (P = 0.05). However, these changes did not manifest along with other glucose clearance measures (P > 0.17) indicating that regardless of in utero treatment or heifer development treatment the reduction in feed input did not greatly influence glucose clearance measures or baseline serum metabolites throughout postpartum, first parity period.

Screening Yeasts from Ruminal Fluid of Dairy Heifer Fed a Different Ratio Roughage to Concentrate Diets

The objective of these studies were to identify ruminal yeast in varying ratios of roughage to concentrate in TMR diets in order to explore yeast diversity by using molecular technique with similarity of rDNA sequence. The experiment was assigned to four 98.6% of cross bred Holstein Friesian heifers with 2 levels and two replicates of roughage to concentrate ratios as： 10：90 （T1） and 50：50 （T2）. The experimental period was 14 days. Rumen fluid sample was collected by stomach tube for total DNA extraction by using silica gel method, and analysis of quantity and quality of DNA by Nanovue and agarose gel electrophoresis. The divergent DI/D2 domain of 26S rDNA was amplified by primers NL-1（5＇-GCA TAT CAA TAA GCG GAG GAA AAG-Y） and NL4 （5＇-GGT CCG TGT TTCAAG ACG G-3＇） by polymerase chain reaction （PCR）. The nucleotide sequences of D l/D2 domain of 26S rDNA were determined using PCR products. Generated sequences were aligned with related species by using the CLUSTAL W. The result showed that an average dry matter intake of TI was 7.00 kg/d and T2 was 6.99 kg/d. DNA concentrate from TIRI, TIR2, T2RI and T2R2 were 106, 131.5, 84 and 182.5 ng//aL, respectively. The purity of DNA was 1.57, 1.76, 1.78 and 1.86, respectively. The divergent D1/D2 domain of 26S rDNA of treatment could be amplified for T1R1 and T2R1 but could not for T1R2 and T2R2. The sequences of D1/D2 domain of 26S rDNA were compared with nucleotide database by BLAST programs （http：//www.ncbi.nlrn.nih.gov/BLAST）, the T2RI yeast-strain was closest to Yarrowia lipolytica. However, yeast strain in T1R1 could not be specifically identified because D 1/132 domain of 26S rDNA seem to represent variable region with number of nucleotide sequence showing 2-3 substitution from known species. The phylogenetic tree based on the sequences of the DI/D2 domain of 26S rDNA showed that TIR! was related to Pichia and Candida （96%） and T2R1 was related to Yarrowia lypolytica （100%）. This study indicated that ruminal yeast strains could be found varying in different ratio of roughage to concentrate.

Effects of replacing steam-flaked corn with shredded sugar beet pulp on feed sorting, behavior, blood metabolites, and growth performance of dairy calves

This experiment was conducted to investigate the effects of partial replacement of steam-flaked corn(SFC)with shredded sugar beet pulp(SBP)in the starter diet on selective intake(sorting),feeding and chewing behavior,blood biochemical parameters,and growth in newborn female Holstein dairy calves.A total of 48 calves(3 d old;40.1±0.84 kg body weight;mean±SE)were randomly assigned to 1 of 2 feeding treatments containing 0 or 25%SBP(percentage of dry matter[DM])in the starter diet.Calves were weaned on d 61 and remained in the study until d 81.Intake of starter feed and total intake of DM(milk DM+starter feed DM),crude protein,and neutral detergent fiber were increased(P<0.05)by feeding SBP;however,intake of starch(P<0.01)and total intake of ether extract(P=0.03)were decreased with no apparent effect on total intake of ME.Average daily gain,feed efficiency,final weight,and skeletal growth also showed no significant changes.Circulating concentrations of glucose,total protein,and albumin were not affected by partial replacement of SBP with SFC;however,higher concentrations of blood urea-N(P=0.01)and a lower albumin-to-globulin ratio(P=0.03)were observed in SBP-vs.SFC-fed calves.Calves fed SBP sorted more for particles retained on the 4.75-mm sieve(P=0.02)and against particles retained on the 0.6-mm sieve and bottom pan(P<0.01).Intake of neutral detergent fibers and starch from particles retained on all sieve fractions was increased and decreased(P<0.01),respectively,by replacing SFC with SBP.Replacement of SBP with SFC was associated with increased meal length and meal size and increased rumination frequency and length,but decreased intervals between rumination(P≤0.01).Calves fed SBP spent more time eating,rumination,and standing and less time lying and non-nutritive oral behaviors(P<0.01).In general,25%replacement of SFC with SBP did not affect calf performance but increased time spent rumination and eating and decreased non-nutritive oral behaviors.