Superovulation and recovery of zygotes from Nubian and Alpine dairy goats

Thirty-five purebred dairy goats (18 Alpines and 17 Nubians) were subjected to a superovulating hormone program consisting of an 11-d 6alpha-methyl-17alpha-acetoxy-progesterone; (MAP; 60 mg) intravaginal sponge treatment; 125 ug i.m. injections of the prostaglandin F(2alpha) analogue cloprostenol on d 1 and 9 of vaginal sponge treatment; and a 3-d, twice-a-day injection of 2.5 mg of pituitary follicle stimulating hormone (FSH-P) i.m. starting at day 9. Vaginal sponges were pulled the morning of day 11 at the time of the fifth FSH-P injection. Of 40 initiated superovulatory cycles, 33 does (10 Alpines and 23 Nubians) responded with an average of 17.7 (range 1 to 29) ovulations. There was no significant difference between the breeds with respect to corpora lutea (CLs) plus follicles ovarian response. A significantly greater (P< 0.05) number of Nubian does were in estrus and mated by 36 h after MAP sponge removal. All does that responded to treatment had done so within 72 h of sponge removal. Of the seven (17.5%) does that showed no estrous response to hormone treatment, six were Alpines (P < 0.01). Six goats (two Alpines and four Nubians) were subjected to a second hormone treatment cycle after a 45-d rest. Five of six does responded to a second hormone treatment cycle with four of five responding with a lower total ovarian response. The interval from sponge removal to mating did not affect the stage or quality of eggs harvested. Rather, the interval from mating to surgical flushing determined the stage of egg development. All animals examined from 24 to 32 h after initial mating had not ovulated. By 50 h, 20 of 22 does had ovulated. A total of 242 ovulated eggs (63%) was harvested, of which 199 (82%) were fertilized. Day 7 flushings yielded 36 eggs (67%), of which 28 (78%) were fertilized. This rate of superovulation, fertilization, and embryo recovery lends credibility to this technique in its ultimate objective of rapidly increasing the number of offspring from superior animals.     

AGPAT6 polymorphism and its association with milk traits of dairy goats

As one of the eight members in the 1-acylglycerol-3-phosphate-O-acyltransferase (AGPATs) family, AGPAT6 is a crucial enzyme for the biosynthesis of glycerolipids and triacylglycerol in eukaryotes, as well as catalyzing the conversion from lysophosphatidic acid to phosphatidic acid. AGPAT6 can be considered as a candidate gene for regulating milk composition. DNA sequencing and PCR-RFLP methods were applied to detect genetic variation in the AGPAT6 gene in 549 Chinese dairy goats. Four polymorphisms (NC_007328.3:g.152G>C, 8124G>A, 9263C>G, 16436G>A) were detected in 5'UTR, intron 2, exon 4, and 3'UTR, respectively. For the KpnΙ locus, the frequencies of the AGPAT6-G allele were 0.955 and 0.936 for SN (Xinong Sannen) and GZ (Guanzhong) dairy goat breeds, respectively. In the PCR-RFLP analysis for KpnΙ, EcoRII, NcoΙ, and BglΙ, the frequencies of the G allele of AGPAT6 were 0.955 and 0.936, 0.694 and 0.819, 0.206 and 0.254, 0.729 and 0.623 for SN and GZ dairy goat breeds, respectively. The 9263C>G mutation revealed a synonymous genetic code of Thr (threonine). Associations between the four mutations and milk traits were analyzed in two dairy goat breeds. At the 9263C>G locus, genotype GG and CG individuals showed significantly better milk performance than genotype CC individuals (P < 0.05). Therefore, the G allele is suggested to be a molecular marker for milk production in dairy goats.     

Reproductive cycle of goats

Goats are spontaneously ovulating, polyoestrous animals. Oestrous cycles in goats are reviewed in this paper with a view to clarifying interactions between cyclical changes in tissues, hormones and behaviour. Reproduction in goats is described as seasonal; the onset and length of the breeding season is dependent on various factors such as latitude, climate, breed, physiological stage, presence of the male, breeding system and specifically photoperiod. In temperate regions, reproduction in goats is described as seasonal with breeding period in the fall and winter and important differences in seasonality between breeds and locations. In tropical regions, goats are considered continuous breeders; however, restricted food availability often causes prolonged anoestrous and anovulatory periods and reduced fertility and prolificacy. Different strategies of breeding management have been developed to meet the supply needs and expectations of consumers, since both meat and milk industries are subjected to growing demands for year-round production. Hormonal treatments, to synchronize oestrus and ovulation in combination with artificial insemination (AI) or natural mating, allow out-of-season breeding and the grouping of the kidding period. Photoperiodic treatments coupled with buck effect now allow hormone-free synchronization of ovulation but fertility results after AI are still behind those of hormonal treatments. The latter techniques are still under study and will help meeting the emerging social demand of reducing the use of hormones for the management of breeding systems.     

Evaluating the fitness of human lysozyme transgenic dairy goats: growth and reproductive traits

While there are many reports in the literature describing the attributes of specific applications of transgenic animals for agriculture, there are relatively few studies focusing on the fitness of the transgenic animals themselves. This work was designed to gather information on genetically modified food animals to determine if the presence of a transgene can impact general animal production traits. More specifically, we used a line of transgenic dairy goats expressing human lysozyme in their mammary gland to evaluate the reproductive fitness and growth and development of these animals compared to their non-transgenic counterparts and the impact of consuming a transgenic food product, lysozyme-containing milk. In males, none of the parameters of semen quality, including semen volume and concentration, total sperm per ejaculate, sperm morphology, viability and motility, were significantly different between transgenic bucks and non-transgenic full-sib controls. Likewise, transgenic females of this line did not significantly differ in the reproductive traits of gestation length and litter size compared to their non-transgenic counterparts. To evaluate growth, transgenic and non-transgenic kid goats received colostrum and milk from either transgenic or non-transgenic does from birth until weaning. Neither the presence of the transgene nor the consumption of milk from transgenic animals significantly affected birth weight, weaning weight, overall gain and post-wean gain. These results indicate that the analyzed reproductive and growth traits were not regularly or substantially impacted by the presence or expression of the transgene. The evaluation of these general parameters is an important aspect of defining the safety of applying transgenic technology to animal agriculture.     

The effect of altered thyroid status on lipid metabolism in Nubian goats

The effects of triiodothyronine (T3)-induced hyperthyroidism and of carbimazole (CZ)-produced hypothyroidism on lipid metabolism were studied in Nubian goats (Capra hircus). T3 treatment decreased the serum, liver and heart triglyceride, cholesterol and phospholipid concentrations. These changes were accompanied by an increase in the activity of lipoprotein lipase (LPL) in the heart and skeletal muscles. CZ treatment at a dose of 90 mg/goat significantly increased the serum triglyceride, liver cholesterol and heart phospholipid. CZ treatment significantly increased the liver and heart triglyceride concentration but the activity of LPL was not affected.     

Fertility prediction in dairy goats from Murciano-Granadina breed: The role of sperm evaluation and female traits

Fertility is one of the most economically important traits in farm animals, due to the direct and indirect costs associated to low pregnancy rates. Thus, one of the priority goals in animal reproduction is to predict the performance that the semen doses will have in vivo based on the quality values obtained in laboratory assays. Attempts have been made for getting a predictive model of fertility of frozen-thawed sperm in dairy goats, but similar studies have not been conducted for chilled goat buck sperm doses that are mostly used for artificial insemination in many countries including Spain. We study how parameters of in vitro sperm quality and characteristics of Murciano-Granadina dairy goats may affect the in vivo fertility obtained after artificial insemination with semen doses chilled at 4 °C. Moreover, this information was used for obtaining predictive models of the fertility. Sixty-three ejaculates from 13 males were used to prepare chilled doses for the insemination of 495 goats over 13 sessions. Fresh and chilled sperm were evaluated for motility and plasma membrane integrity with a computer-assisted sperm analysis system and flow cytometry, respectively. Fertility was determined at parturition, according to the kidding goats. Overall fertility was 59.6%. Pearson’s correlation coefficients between in vivo fertility and quality variables of fresh sperm were not significant and were low (below 0.34 in absolute value) for chilled sperm. Females’ characteristics had a low negative impact on fertility (correlation coefficients of ?0.19 with age, ?0.20 with parturitions and ?0.11 with total milk yield obtained in the best lactation). Fixed and mixed logistic regression procedures were used trying to explain the fertility results. None of the models accurately predicted fertility, but the best models included the percentage of total motile sperm or average path velocity from fresh semen, age of the females and the session effect (uncontrolled environmental effects). These analyses showed that primiparous goats were 2.42 times more likely to get pregnant than goats that had kidded four or more times. Our field assay data on fertility in Murciano-Granadina dairy goats highlighted the importance of making quality controls of sperm, of choosing the doses presenting high percentages of motile sperm exhibiting regular trajectories and of selecting the youngest goats for AI, after their first kidding. Efforts should continue to obtain better predictive models for improving fertility in goat dairy herds.     

QTL affecting conformation traits in Angora goats

A genomic screen for quantitative trait loci (QTL) affecting conformation traits was performed by genotyping 288 Angora goats offspring from 8 half-sub families with 76 microsatellite markers. The following traits were recorded: weaning weight (WW, Kg); stature (S, cm); chest depth (CD, cm); shoulder width (SW, cm); rump length (RL, cm); rump width (RW, cm); head length (HL, cm); head width (HW, cm); shin circumference (SC, cm); chest circumference (CC, cm) and body length (BL, cm). Data were analyzed using the QTL Express program. A total of 5 QTL were detected in five chromosomes with chromosome wide significance level. For the 11 analysed traits the results were: evidence of two possible QTL for HL were found in chromosomes 1 and 4, a putative QTL for trait CD was found in chromosome 2, evidence for BL was found in chromosome 8 and a possible QTL was found for trait CC in chromosome 9. The results reported here show the existence of chromosomal regions in Angora goats involved in conformation traits and represent the first in depth search in some specific-genome sections in order to identify and characterize the genetic variability involved in these traits.     

QTL affecting fleece traits in Angora goats

With the aim to detect chromosome segment (quantitative traits loci, QTL) affecting fleece traits in Angora goats, a genome scan using 76 microsatellite markers spanning 1261 cM on 21 chromosomes was conducted. Eight paternal half-sib families were used, which included a total of 288 kids from a dispersed nucleus herd.Mid-side mohair samples were taken from kids at 4 months of age and eight phenotypic fleece traits were measured.We found putatives QTL for coefficient of variation of average fiber diameter (CVAFD) in chromosome 1 and 13, for kemp fiber (KEMP) in chromosome 5 and for discontinuous medullated fibers (DISC) and staple length (SL) in chromosome 2.These results demonstrate the segregation of quantitative traits involved in mohair production. Further studies will concentrate on these regions to characterize the variation of these QTL.     

Sexual stimulation of male dairy goats

The objective of the present study was to investigate methods for enhancing the sexual performance of male dairy goats in the context of controlled breeding (“hand-mating”) and semen collection. Nine male goats were individually exposed to a single restrained estrous female who served either as a natural-mating stimulus or as a teaser female for semen collection. Tests were conducted under four conditions: (1) with another male watching in a runway adjacent to the test arena (W); (2) after observing the previously tested male court and copulate with the stimulus female (S); (3) a combination of the aforementioned two treatments (S---W); (4) an unstimulated control treatment (C).In the natural-mating tests, sexual performance was significantly enhanced by each of the forms of stimulation. Differences in sexual performance under the three stimulation treatments were not statistically significant. In the artificial-mating tests, latencies to mount and ejaculate (into the artificial vagina) were significantly shortened by the S and S---W treatments, but not by being watched (W treatment). Again, stimulation treatments did not differ significantly.Sexual stimulation did not affect semen volume or concentration.The improved sexual performance of stimulated male goats may result in a significant sav saving of time and labor to animal breeders involved in hand-mating or semen collection.     

Reproductive response to suckling manipulation in Spanish goats

One hundred and fifty-six Spanish does were used to evaluate the effect of suckling manipulation on postpartum breeding. Does were divided into four herds dependent upon their kidding dates (range from October to January) and location. All kids were nursed ad libitum for approximately 30 days following birth. Groups were then subdivided, and does with kids were randomly allotted to one of the following treatment groups: 1) continuous suckling (CS), 2) once-daily suckling (ODS) or 3) early weaning (EW). Nonlactating does (NL) which lost a kid or aborted were also evaluated for rebreeding performance. At least one fertile male equipped with a marking harness was placed with each treatment group for estrus detection. After 30 days, ODS kids were returned to their dams. The proportion of does exhibiting estrus within 60 days postpartum was greater for ODS and EW does compared to CS does (P<0.05 and P<0.001, respectively). Postpartum interval to first estrus was shorter (P<0.05) for ODS does than for CS does (41.7 and 48.0 days, respectively). The percentage of does conceiving within 60 days postpartum was 25.0, 44.7, 74.4 and 70.7% for CS, ODS, EW and NL does, respectively. The interval from parturition to conception was shorter (P<0.05) for ODS does (43.6 days) than for CS does (50.4 days). Overall kid production was 1.87 kids/doe/year. These results indicate that reducing the suckling stimulus in Spanish does during the breeding season may result in an earlier return to estrus with a greater percentage of does rebreeding within 60 days postpartum.     

A novel polymorphism of the lactoferrin gene and its association with milk composition and body traits in dairy goats

Milk composition and body measurement traits, influenced by genes and environmental factors, play important roles in value assessments of efficiency and productivity in dairy goats. Lactoferrin (LF), involved in the efficient expression of protein in milk, is also an anabolic factor in skeletal tissue and a potent osteoblast survival factor. Therefore, it is an important candidate gene for milk composition and body measurement trait selection in marker-assisted selection. We employed PCR-SSCP and DNA sequencing to screen the genetic variations of the LF gene in 549 Chinese dairy goats. A novel single-nucleotide polymorphism (SNP) (G198A in exon II) of the LF gene was detected. The frequencies of the AA genotype were 0.0285 and 0.0261 in GZ and SN populations, respectively. Both populations were found to have low levels of polymorphism and were in Hardy-Weinberg disequilibrium (P < 0.05). We found significant (P < 0.05) associations of the SNP marker with milk protein and acidity in the total population; animals with the AA genotype had higher mean values for milk protein than those with the GA genotype. Animals with genotype AA had higher mean values for withers height than those with genotype GG (P < 0.05). We concluded that this SNP of the LF gene has potential as a genetic marker for milk composition and body traits in dairy goat breeding.     

Lysine flux in dry and lactating dairy goats

The objective of this experiment was to test the hypothesis that the physiological state of lactation is accompanied by both an increase in total plasma lysine flux (rate of loss and replacement of lysine) and a net reduction in flux through the plasma lysine pool after accounting for lysine secreted in the milk. Eight lactating French Alpine does were primed and infused for three hours with solutions of alpha15N L-lysine HCl in 0.9% saline through indwelling jugular vein catheters. Enrichment of circulating plasma lysine by continuous intravenous infusion of alpha15N L-lysine was used to estimate whole body lysine flux. This procedure was repeated one month after cessation of milking. Total plasma lysine flux was similar for dry and lactating does (116.6 and 123.0 mmol/d, SEM 16.6 mmol), but 54.2 mmol/d lysine was secreted as milk protein during lactation. Direct measurement of lysine absorption from the lower tract and independent measurement of lysine degradation are needed to provide a more complete portrait of caprine lysine kinetics.     

Genetic variability in milking speed of dairy goats

The present investigation deals with the genetic variability of milking speed, measured as the volume of milk collected during the first minute of milking (MD1), and its association with dairy traits. Data originated from 2589 lactations of 1421 Alpine goats, sired by 93 bucks, measured between 1985 and 1997 at the Moissac Goat Experimental Station (Lozère, France). Two genetic analyses were carried out. Firstly, a polygenic model was used to estimate genetic and phenotypic parameters among milking speed and dairy traits using a multiple-trait animal model. Secondly, segregation analysis was used to test the hypothesis of mixed model inheritance (polygenes + major gene) for MF1. Heritability and repeatability of MF1 under the polygenic model were high (0.65 and 0.82, respectively). Estimated genetic and phenotypic correlations between milking speed and dairy traits were low, positive for yields and negative for contents. Segregation analysis yielded a highly significant likelihood ratio, confirming the segregation of a major gene with two alleles with partial dominance. The difference between the mean values of the two homozygotes was around 2.3 phenotypic standard deviation units of the trait. The major gene explained more than 60% of the estimated total genetic variance. The estimate of the 'residual' heritability, after taking into account the effect of the major locus, was 0.30.     

Reproductive period affects water intake in heat-stressed dehydrated goats

Water intake following dehydration was studied in pregnant (N = 5), lactating (N = 4) and nonpregnant, nonlactating (N = 5) Swedish domestic goats (Capra hircus) to investigate if reproductive period affected drinking. Plasma cortisol concentration and the hematocrit value were measured to evaluate stress. The goats were water deprived from 9.00 h until 15.05 h the next day. They were fed at 7.00 and 15.20 h. On the second day, ambient temperature was increased from 20°C to 38–39.5°C for 5.15 h to accelerate water losses. Water temperature during erhydration was 35 ± 1°C. Plasma Na concentration and osmolality increased most in dehydrated and heat-stressed pregnant and lactating goats. Pregnant goats lost 2.2 kg of their body weight. They drank 3.5 l immediately, followed by 2.5 l during afternoon eating. Lactating goats lost 4.9 kg and drank 6.3 l at once, and 3.9 l during feeding. Nonpregnant, nonlactating goats lost 1.7 kg and drank 2.6 l followed by 0.6 l. The large water consumption in pregnant and lactating goats caused hyponatremia and hemodilution, but they continued to drink during the night (0.5 ± 0.2 l and 0.8 ± 0.5 l, respectively). Renal free water clearance increased in all periods, with a long-lasting water diuresis during pregnancy. Plasma cortisol concentrations and the hematocrit values rose in connection with water intake. These results imply that the thirst center became less sensitive to inhibitory signals from the oropharyngeal tract and the diluted blood plasma during pregnancy and lactation. Catching sight of water was the most exciting procedure during these experiments.     

Characterisation of the genetic effects of the ADFP gene and its association with production traits in dairy goats

Adipose differentiation-related protein (ADFP) is important for regulation of lipid metabolism and insulin secretion in beta-cells. In this study, we investigated polymorphisms within the caprine ADFP gene and determined its relationship with production traits. As there was no sequence information available for the caprine ADFP gene, we generated DNA sequence data and examined the genomic organisation. The caprine ADFP gene is organised into 7 exons and 6 introns that span approximately 8.7 kbp and is transcribed into mRNA containing 1353 bp of sequence coding for a protein of 450 amino acids. The protein sequences showed substantial similarity (71–99%) to orthologues from cattle, human and mouse. We identified polymorphisms in the sequences using DNA sequencing, PCR-RFLP and forced PCR-RFLP methods. Seven single nucleotide polymorphisms (SNPs) were identified using samples from 4 different goat populations consisting of 1408 healthy and unrelated individuals. Six haplotypes involving the 7 SNPs from the caprine ADFP gene were identified and their effects on production traits were analysed. Haplotype 6 had the highest haplotype frequency and was highly significantly associated with chest circumference and milk yield in the analysed populations. The results of this study suggest that the ADFP gene is a strong candidate gene affecting production traits and may be used for marker-assisted selection and management in Chinese dairy goat breeding programmes.     

Repeatability of traits for characterizing feed intake patterns in dairy goats: a basis for phenotyping in the precision farming context

In ruminants, feeding behaviour variables are parameters involved in feed efficiency that show variation among individuals. This study aimed to evaluate during the first two production cycles in ruminants the repeatability of feed intake pattern, which is an important aspect of feeding behaviour. Thirty-five dairy goats from Alpine or Saanen breeds were housed in individual pens at four periods (end of first gestation, middle of first and second lactations and middle of second gestation which is also the end of first lactation) and fed a total mixed ration (TMR) ad libitum. Individual cumulative dry matter intake (DMI) was automatically measured every 2 min during the last 4 days of each period. Feed intake pattern was characterized by several measures related to the quantity of feed eaten or to the rate of intake during the 15 h following the afternoon feed delivery. Two main methods were used: modelling cumulative DMI evolution by an exponential model or by a segmentation-clustering method. The goat ability to sort against dietary fibre was also evaluated. There was a very good repeatability of the aggregate measures between days within a period for a given goat estimated by the day effect within breed and goat, tested on the residual variance (P > 0.95). The correlations between periods were the highest between the second and either the third or fourth periods. With increasing age, goats sorted more against the fibrous part of the TMR and increased their initial rate of intake. Alpine goats ate more slowly than Saanen goats but ate during a longer duration. Principal component analysis (PCA) was performed on all the aggregate measures of feed intake patterns. The factor score plots generated by the PCA highlighted the opposition between the different measures of feed intake patterns and the sorting behaviour. The projection of the animals on the scoring plots showed a breed effect and that there was a continuum for the feed intake pattern of goats. In conclusion, this study showed that the feed intake pattern was highly repeatable for an animal in a given period and between periods. This means that phenotyping goats in a younger age might be of interest, either to select them on feeding behaviour and choose preferentially the slow eaters or to adapt the quantity offered and restrict feed delivery to the fast eaters in order to increase feed efficiency and welfare by limiting the occurrence of acidosis, for example.     

Nonsurgical collection of blastocysts from dairy goats

In two trials, eight attempts were made to collect fertilized ova from dairy goats by nonsurgical methods. In both trials the cervix of each doe was dilated by inserting a Laminaria japonica tent device into the cervical canal prior to flushing. In Trial 1, an attempt was made to collect embryos from four nonsuperovulated does by flushing phosphate-buffered saline (PBS) through a rigid pipette. Little fluid and no embryos were recovered from the does. All four donors were in estrus two days after the procedure. In the second trial, FSH-superovulated does were collected on day 5 following estrus. The donors were anesthetized, and a modified Foley catheter was passed through the cervical canal. In three does, a 24 ga. two-way Foley was stiffened with a size 10 (French) polypropylene catheter which penetrated the Foley, extending 7 cm beyond the tip. Recovery of flushing medium with this device was minimal, and laparotomy of one doe revealed a punctured uterus. Replacement of this device with a different catheter, through which a polypropylene catheter (size 5 Fr.) penetrated only 1 to 2 cm, resulted in satisfactory return of infused PBS, and recovery of two blastocysts and one degenerated ovum from this doe. Use of the same device on a second doe without laparotomy resulted in collection of seven blastocysts and three degenerated ova. Of three observed donors that received Laminaria tents (including one which was not flushed) two were in estrus three days after the procedure, while unused synchronized recipients showed normal cycle lengths. Surgical transfer of two blastocysts from each donor to each of two synchronized recipients resulted in the birth of twin kids from one recipient doe. The study demonstrates the feasibility of embryo collection from dairy goats by nonsurgical means.     

The effect of feed restriction on certain haematological indices,enzymes and metabolites in Nubian goats

• 1.1. Some effects of restricting feed intake for 96 or 168 hr were determined in male Nubian goats.
• 2.2. Goats restricted for 96 hr lost 11.6% of their body weight, and goats restricted for 168 hr lost 19.8%.
• 3.3. Feed restriction for up to 168 hr did not produce significant effects on the heart rate, respiratory rate or rectal temperature.
• 4.4. Haemoglobin concentration, packed cell volume and erythrocyte number were all decreased by feed restriction. There was also a tendency towards eosinopenia and lymphopenia.
• 5.5. Feed restriction for 96 or 168 hr raised the plasma activity of aspartate transaminase, and did not affect significantly cholinesterase activity. Plasma amine oxidase activity was significantly reduced in goats restricted for 168 hr.
• 6.6. Feed restriction produced significant increases in the blood or plasma concentrations of lactate. pyruvate, non-esterified fatty acids, cholesterol, ketone bodies and bilirubin.
• 7.7. Significant decreases were found in the concentrations of total protein and calcium.
• 8.8. No significant changes were observed in the plasma concentrations of glucose, sodium or potassium.