M. Carriquiry

A polymorphism in the insulin-like growth factor 1 gene is associated with postpartum resumption of ovarian cyclicity in Holstein-Friesian cows under grazing conditions

BackgroundInsulin-like growth factor 1 (IGF-1) gene is considered as a promising candidate for the identification of polymorphisms affecting cattle performance. The objectives of the current study were to determine the association of the single nucleotide polymorphism (SNP) IGF-1/Sna BI with fertility, milk production and body condition traits in Holstein-Friesian dairy cows under grazing conditions.MethodsSeventy multiparous cows from a commercial herd were genotyped for the SNP IGF-1/Sna BI. Fertility measures evaluated were: interval to commencement of luteal activity (CLA), calving to first service (CFS) and calving to conception (CC) intervals. Milk production and body condition score were also evaluated. The study period extended from 3 wk before calving to the fourth month of lactation.Results and discussionFrequencies of the SNP IGF-1/Sna BI alleles A and B were 0.59 and 0.41, respectively. Genotype frequencies were 0.31, 0.54 and 0.14 for AA, AB and BB, respectively. Cows with the AA genotype presented an early CLA and were more likely to resume ovarian cyclicity in the early postpartum than AB and BB ones. No effect of the SNP IGF-1/Sna BI genotype was evidenced on body condition change over the experimental period, suggesting that energy balance is not responsible for the outcome of postpartum ovarian resumption in this study. Traditional fertility measures were not affected by the SNP IGF-1/Sna BI.ConclusionTo our knowledge this is the first report describing an association of the SNP IGF-1/Sna BI with an endocrine fertility measure like CLA in cattle. Results herein remark the important role of the IGF-1 gene in the fertility of dairy cows on early lactation and make the SNP IGF-1/Sna BI an interesting candidate marker for genetic improvement of fertility in dairy cattle.

Reproductive and productive response to suckling restriction and dietary flushing in primiparous grazing beef cows

The objectives of the present experiment were to analyse the reproductive and productive responses to suckling-restriction treatments and flushing in primiparous grazing beef cows. During 3 years, 153 primiparous anoestrus cows were assigned randomly to one of four treatments in a 2 by 2 factorial arrangement of suckling-management treatments and flushing. Suckling-restriction treatments started at 61 ± 10 days postpartum and consisted of applying nose plates to calves for 12 days (i.e. TS treatment) or 5 days of isolation of the calf from the cow followed by applying nose plates to calves for 7 days as calves were reunited with their mothers (i.e. IS treatment). Nutritional treatments (flushing v. control) started at the beginning of the breeding season, immediately after the suckling-restriction treatments were finished (73 ± 10 days postpartum), with cows receiving or not receiving 2 kg/day of whole-rice middling for 22 days. Cow body condition score (BCS) was recorded every 20 days from calving until 120 days postpartum. Duration of postpartum anoestrus (PPA) and probability of cyclicity were estimated by plasma progesterone concentrations analysed in weekly samples. Pregnant cows were determined by ultrasound 42 days after bull introduction (early pregnancy; EP) and 30 days after the end of the breeding season (total pregnancy; TP). BCS at calving and changes in BCS from calving to the day of BCS nadir (ΔBCS) varied among years depending on forage availability and weather conditions. Increased cow BCS at calving decreased PPA (b = –41 days, P < 0.0001) and, in interaction with ΔBCS, increased EP (P < 0.008) and TP (P < 0.003). Calf weights at weaning and average daily gain were not affected by suckling-restriction or flushing treatments. Isolated temporary suckling control reduced PPA by 11 days when compared with temporary suckling control (P < 0.004). Flushing increased EP by 40%, which was also affected by BCS at calving and was greater in cows that gained, than in those that maintained or lost BCS. We conclude that flushing was useful in improving early pregnancy rates of primiparous beef cows with ‘suboptimal’ body condition (lower than 4.5) at calving and grazing native pasture.

Metabolic and endocrine profiles of primiparous beef cows grazing native grassland. 1. Relationships between body condition score at calving and metabolic profiles during the transition period

The body condition score (BCS) at calving has been postulated as the main factor in the interaction of nutrition and reproduction in beef-cow ecosystems. The objective of the present study was to analyse the effect of BCS at calving on endocrine and metabolic profiles during the transition period in primiparous Hereford cows (n = 56) grazing native grassland. Cow BCS was registered and plasma insulin, insulin-like growth factor-I (IGF-I) and metabolites (concentrations of urea, albumin, cholesterol, total protein, non-esterified fatty acids (NEFA)) were determined in plasma from –30 to +45 days postpartum (DPP). The effect of BCS at calving (low ≤3.5 and moderate ≥4; 1–8 visual scale) on BCS evolution and hormone and metabolite concentrations were analysed using a time repeated-measures analysis. Cow BCS, NEFA, urea and IGF-I profiles were affected (P < 0.05) by the BCS at calving and DPP interaction, while insulin tended (P = 0.06) to be affected only by BCS at calving. The low-BCS cows presented a smaller loss of BCS during the prepartum than did moderate-BCS cows, and a delayed BCS recovery during the postpartum. The increase in plasma NEFA was greater (P < 0.05) and started earlier during the prepartum period in the low-BCS cows. Protein concentrations increased during prepartum to +30 DPP, while albumin and urea concentrations were maintained until calving and decreased during the postpartum. Urea concentrations were greater (P < 0.05) during prepartum in low-BCS cows. Concentrations of IGF-I and insulin were greater (P < 0.05) in moderate- than low-BCS cows during prepartum, but did not differ between the groups after calving. No effects were observed in calf weight or milk production at +45 DPP. The association between BCS during prepartum and at calving with the endocrine and metabolic profiles (positive: insulin, IGF-I; negative: NEFA and urea) reflected a better nutritional status and plasticity to negative energy balance on moderate cows. This different endocrine milieu did not affect calf weight and/or milk production. In conclusion, the BCS at calving affected the metabolic and endocrine profile during the transition period of primiparous beef cows grazing native grassland.

Metabolic and endocrine profiles and reproductive parameters in dairy cows under grazing conditions: effect of polymorphisms in somatotropic axis genes

BackgroundThe present study hypothesized that GH-AluI and IGF-I-SnabI polymorphisms do change the metabolic/endocrine profiles in Holstein cows during the transition period, which in turn are associated with productive and reproductive parameters.MethodsHolstein cows (Farm 1, primiparous cows, n = 110, and Farm 2, multiparous cows, n = 76) under grazing conditions were selected and GH and IGF-I genotypes were determined. Blood samples for metabolic/endocrine determinations were taken during the transition period and early lactation in both farms. Data was analyzed by farm using a repeated measures analyses including GH and IGF-I genotypes, days and interactions as fixed effects, sire and cow as random effects and calving date as covariate.Results and DiscussionFrequencies of GH and IGF-I alleles were L:0.84, V:0.16 and A:0.60, B:0.40, respectively. The GH genotype was not associated with productive or reproductive variables, but interaction with days affected FCM yield in multiparous (farm 2) cows (LL yielded more than LV cows) in early lactation. The GH genotype affected NEFA and IGF-I concentrations in farm 1 (LV had higher NEFA and lower IGF-I than LL cows) suggesting a better energy status of LL cows.There was no effect of IGF-I genotype on productive variables, but a trend was found for FCM in farm 2 (AB cows yielded more than AA cows). IGF-I genotype affected calving first service interval in farm 1, and the interaction with days tended to affect FCM yield (AB cows had a shorter interval and yielded more FCM than BB cows). IGF-I genotype affected BHB, NEFA, and insulin concentrations in farm 1: primiparous BB cows had lower NEFA and BHB and higher insulin concentrations. In farm 2, there was no effect of IGF-I genotype, but there was an interaction with days on IGF-I concentration, suggesting a greater uncoupling somatropic axis in AB and BB than AA cows, being in accordance with greater FCM yield in AB cows.ConclusionThe GH and IGF-I genotypes had no substantial effect on productive parameters, although IGF-I genotype affected calving-first service interval in primiparous cows. Besides, these genotypes may modify the endocrine/metabolic profiles of the transition dairy cow under grazing conditions.

Metabolic and endocrine profiles of primiparous beef cows grazing native grassland. 2. Effects of body condition score at calving, type of suckling restriction and flushing on plasmatic and productive parameters

The objective of the present experiment was to analyse the effect of body condition score (BCS) at calving, type of suckling restriction and flushing on metabolic and endocrine profiles, and productive and reproductive responses of primiparous beef cows grazing native grassland. Primiparous beef (n = 56) cows in anestrus classified by BCS at calving (low ≤3.5 and moderate ≥4; 1–8 visual scale) were assigned randomly to four treatments in a two by two factorial arrangement of type of suckling restriction and flushing. Type of suckling restriction started at 55 ± 10 days postpartum (DPP ± s.e.m.; Day 0 = initiation of the treatment) and consisted of applying nose plates to calves for 12 days (i.e. TS treatment) or 5 days of isolation of the cow–calf pair, followed by applying nose plates to calves for 7 days as calves were reunited with their mothers (i.e. IS treatment). Immediately after the suckling restriction treatments were finished, the breeding season started, and each cow received (flushing group) or not (control group) 2 kg/day (fresh basis) of whole-rice middling for 22 days. The BCS was superior in moderate-BCS cows through the experiment. The type of suckling restriction did not affect any plasma parameter, but insulin-like growth factor I (IGF-I) concentrations increased in all cows during suckling restriction. Cholesterol concentration was affected by flushing × day interaction (P < 0.05), while insulin and IGF-I concentrations were affected by the interaction among BCS at calving, flushing and days (P < 0.03). Flushing increased cholesterol concentration in both BCS groups at calving, while insulin and IGF-I concentrations increased during flushing only in moderate-BCS cows. Suckling restriction, flushing, and BCS at calving did not affect calf weight or milk production. Moderate BCS cows had a shorter postpartum anestrous interval (PPI) (98 vs 123 DPP; P < 0.01). Isolated type of suckling reduced postpartum anestrous interval when compared with TS treatment (97 vs 115 DPP, P < 0.05). Early pregnancy rate was greater in flushed than in control cows (0.8 vs 0.55, P < 0.01) and in moderate-BCS cows than in low-BCS cows (0.84 vs 0.46, P < 0.01). Total pregnancy rate was also greater in flushed and moderate cows and tended to be affected by the interaction between flushing and BCS at calving (P = 0.06; flushed cows: moderate = 1 vs low = 0.5, P < 0.08; and control cows: moderate = 0.8 vs low = 0.4, P < 0.09). These results confirmed the great value of suckling restriction and flushing during post-calving and relevance of BCS at calving as a link between energetic nutrition and metabolic and reproductive processes in primiparous beef cows grazing native grassland.

Changes in body composition during the winter gestation period in mature beef cows grazing different herbage allowances of native grasslands

The aim of this study was to evaluate the effect of controlling the grazing intensity of native pastures, through the herbage allowances (HA) on body composition (water, protein, and fat) of beef cows of different cow genotype (CG; purebred: Angus and Hereford; PU, and crossbred: reciprocal F1; CR). Mature beef cows (n = 32) were used in a complete randomised block design with a factorial arrangement of HA (2.5 vs 4 kg DM/day; LO vs HI) and CG (PU vs CR). The experiment was conducted during 3 years and at the end of the third year at 150, 210, and 240 ± 10 days of gestation and 190 ± 10 days postpartum body composition was estimated using the urea dilution technique. At 192 ± 10 days postpartum cows were slaughtered and all tissues and organs were weighed and samples were collected for chemical composition analyses. During the winter gestation period, body condition score was greater (P < 0.05) in HI than LO cows and in CR than PU cows. Relative body water (g/kg of empty bodyweight) was greater (P ≤ 0.02) in HI than LO cows and in CR than PU cows, whereas relative body protein did not differ between HI and LO, but tended (P = 0.10) to be greater in CR than PU cows. In contrast, relative body fat tended (P = 0.10) to be greater and gross energy content was greater (P < 0.01) in HI than LO cows, whereas they did not differ between CR and PU cows. Relative body water increased (P < 0.01) from 150 to 210 days of gestation for all cows whereas relative body fat decreased (P < 0.05) and body protein increased (P < 0.05) from 150 to 210 days of gestation in PU but not in CR cows. These results suggest that HI maintained greater body condition score and retained gross energy content when compared with LO cows, and CG affected not only body composition (greater body fat and protein in CR than PU cows) but also composition of mobilised/retained weight during the winter gestation period with a greater protein tissue mobilisation in CR than PU cows.

Hepatic Expression of Insulin-Like Growth Factor-1 in Underfed Pregnant Ewes

The liver is one of the most important visceral organs, which represents a large contribution to whole animal energy expenditure and the major synthetic site of insulin-like growth factor-1 (IGF-1) peptide. Decreased plane of nutrition acts by reducing the metabolic rate and mass of metabolic tissues, such as liver. Also, undernutrition results in the reduced circulating IGF-1 concentrations, due to the uncoupled growth hormone-IGF (GH-IGF) axis. This study investigated whether a 22-day period of undernutrition (half maintenance) could affect liver mass and IGF-1 protein and gene expression. Sixteen pregnant ewes fed all (n = 9) or half (n = 7) of their maintenance energy requirements were slaughtered on day 7 of pregnancy (oestrus = day 0). Body and liver mass, IGF-1 plasmatic concentrations and liver IGF-1 mRNA and protein expression were determined. Liver mass and the proportion of liver mass to empty body weight were lower in underfed animals. While IGF-1 plasmatic concentrations were lower in undernourished ewes, no differences in liver mRNA expression were found. This is the first time that differences in immunohistochemistry intensity and total content are reported in sheep. In summary, the decreased plasma IGF-1 concentrations induced by undernutrition in ewes was not associated with its reduced hepatic mRNA or protein expression, but to a decrease in liver mass.

Endocrinología metabólica en la vaca lechera durante el período de transición y su relación con el reinicio de la ciclicidad ovárica

La produccion de leche se ha duplicado en las ultimas decadas y concomitantemente el desempeno reproductivo ha disminuido. Las limitantes reproductivas son el reinicio de la ciclicidad ovarica luego del parto y la mortalidad embrionaria temprana. Esta revision resume algunos trabajos realizados en los ultimos 10 anos respecto de los cambios metabolicos y endocrinos durante el periparto y su relacion con el reinicio de la ciclicidad ovarica en vacas lecheras en nuestro pais. Hemos caracterizado estos cambios en vacas primiparas y multiparas durante el periodo de transicion. Se realizaron estudios con dietas diferenciales en energia y proteina en el pre y postparto con el objetivo de modificar el comportamiento productivo y reproductivo, determinandose en ellos hormonas y metabolitos. Los autores concluyen que los indicadores endocrinos y metabolicos son buenas herramientas de diagnostico que integran la memoria metabolica y el estado nutricional reciente, siendo esenciales para comprender como el eje reproductivo es informado respecto del balance energetico negativo que ocurre en este periodo.