Effects of parity, seasonal heat stress, and colostrum collection time postpartum on colostrum quality of Holstein cattle in an arid region.

The aim of this study was to determine effects of parity (primiparous vs. multiparous), seasonal heat stress at calving (summer vs. winter), and time postpartum on some parameters associated with colostrum quality in Holstein cows reared in the Sonoran Desert ecosystem. Forty-seven cows (11 primiparous and 36 multiparous) expected to calve during summer, and 46 cows during winter (14 primiparous and 32 multiparous) were randomly selected. Management and feeding before and after parturition were similar for cows in both seasons. After parturition, colostrum from all cows was evaluated for volume, weight, temperature, density, and content of fat, protein, solids non-fat (SNF), and immunoglobulins (IGG). Data were analyzed with a model that included effects of parity status, calving season, and time postpartum, as well as all interactions. Colostrum produced in summer was warmer (P < 0.01) by almost 6 °C than winter colostrum, while colostrum from multiparous was warmer (P = 0.02) by 1.2 °C than that produced by primiparous cows. Colostrum volume and weight were not impacted by parity, calving season or time postpartum. Density, protein, and SNF content in colostrum were higher (P < 0.01) in multiparous vs. primiparous cows, as well as at parturition (0 h postpartum) than at 12 h postpartum (P < 0.01). At calving (0 h), spring colostrum had higher fat content (P < 0.01) and lower (P < 0.01) IGG concentration than that collected in summer, and no difference (P > 0.05) between seasons was observed for these components at 12 h postpartum. Multiparous cows produced colostrum with higher (P < 0.01) IGG concentrations than primiparous cows. In conclusion, only 0-h colostrum and that from multiparous cows was categorized as "Excellent," meanwhile the colostrum produced under summer heat stress was characterized as "Good" with reduced fat content. While the lacteal secretion collected at 12 post-partum still classified as colostrum, substantially lower contents of IGG, protein, fat, and SNF decreased its classification to "Poor" from the classification of "Excellent" at 0 h postpartum.

Holstein heifers in desert climate: effect of coat color on physiological variables and prediction of rectal temperature.

Two hundred Holstein heifers were divided by hair coat color in black (n1 = 60), white (n2 = 62), and mixed (n3 = 78) to accomplish two objectives: (1) to compare physiological variables using an analysis of variance, and (2) to construct regression equations to predict rectal temperature. In each heifer, rectal temperature (RT), respiration frequency (RF), and body surface temperatures (obtained with infrared thermography in eye, nose, forehead, head, neck, ear, shoulder, flank, belly, leg, loin, rump, and vulva) were measured. Black heifers had more RF and RT (P < 0.01) than mixed and white coat heifers; white heifers had similar RT than mixed color heifers, but they exhibited less RF (P < 0.05). In general, black and mixed coat color heifers had higher BST (P < 0.01) than white heifers in the majority of the anatomical regions measured. For black coat heifers, the best regression model to predict RT included three predictor variables: [RT = 35.59 - 0.013 (RH) + 0.045 (RF) + 0.019 (TEar); R2 = 71%]. For white coat heifers, the best model included two predictor variables: [RT = 35.29 + 0.035 (RF) + 0.033 (TForehead); R2 = 71%]; and for mixed coat color heifers, the best model included two predictor variables: [RT = 35.07 + 0.022 (RF) + 0.038 (THead); R2 = 44%]. Heifers with dark hair coat color showed higher physiological constants than white heifers; the prediction of rectal temperature was more precise in heifers with well-defined hair coat color. Physiological and climatic variables, along with infrared thermography, represent an appropriate combination to predict rectal temperature in Holstein heifers with predominant white or black hair coat color.

Increasing shade area in feedlot heifers during heat stress: physiological and performance parameters.

Heat stress is a great challenge for feedlot operations established in arid zones. The aim of this study was to evaluate if increasing shade area in the pen improved physiological and productive variables in feedlot heifers under hot climate. A total of 510 European and Zebu heifers were randomly assigned to six pens which were divided in two treatments: (1) three pens with 100 heifers each with a shade area of 2.7 m2/head (control group [C]); and (2) three pens with 70 heifers each with a shade area of 3.7 m2/head (treated group [T]). Physiological variables respiratory frequency (RF) and body surface temperature (BST) of several anatomic regions were taken from 30 heifers per treatment (i.e., 10 heifers/pen). Feed intake on pen basis was recorded weekly and heifers were individually weighted on days 1, 26, and 66 of the study to calculate performance variables. Relative humidity (RH) and ambient temperature (AT) were recorded and used to estimate the temperature-humidity index (THI). Data was analyzed with analysis of variance. The average THI during the study was 81.7 units, which was categorized as dangerous heat stress. In both shaded areas, European heifers showed higher (P < 0.05) RF than Zebu heifers. In the afternoon, the temperature of head, neck, loin, paddle, and belly was higher (P < 0.05) in C compared with T. Heifers under T showed better (P < 0.05) daily weight gain (DWG), total weight gain (TWG), feed conversion (FC), and feed efficiency (FE) than heifers in C, with no effect on dry matter intake (DMI). Results indicate that during hot summer months, Zebu showed more tolerance to heat stress than European heifers; however, heifers under a shade area of 3.7 m2/head had better productive performance than those under a shade area of 2.7 m2/head during the finishing phase of the feedlot. Increasing the shade area in the finishing phase of beef cattle on feedlot improved some physiological and productive responses during heat stress.

Relationships of body surface thermography with core temperature, birth weight and climatic variables in neonatal lambs born during early spring in an arid region.

The main cause of death in newborn lambs is hypothermia, so is necessary to identify the factors affecting variations in body surface temperatures of sheep neonates because approximately 60% of their body heat losses occur through the skin. This study aimed to establish relationships among body surface thermography from different regions with rectal temperature (RT), birth weight (BW) and climatic variables in hair breed newborn lambs during early spring in an arid region. Data of body surface temperatures measured by infrared thermography (entire head, eye, muzzle, ear, entire body, shoulder, rump, loin, right flank, belly and leg), RT and BW were collected at 0, 12 and 24 h post-lambing in 85 lambs born in early spring. Relative humidity [RH], temperature [Te] and temperature-humidity index [THI] were also recorded. RT was not correlated with surface temperatures at 0 and 24 h, but it was at 12 h with all of them (0.36 ≤ r ≤ 0.44). BW and some surface temperatures were negatively correlated at 0 and 24 h (-0.24 ≤ r ≤ -0.30), but positively at 12 h (0.25 ≤ r ≤ 0.27). All surface temperatures were positively correlated (0.51 ≤ r ≤ 0.85) with Te and THI in the three sampling times. Principal component (PC) analysis showed that PC1 explained the majority of the variance (71-72%), followed by PC2 (8-9%) at 0, 12 and 24 h. Body surface temperatures increased as Te and THI also increased, but decreased with the increase in HR. In conclusion, under early spring environment (predominantly cold), the variations in body surface temperatures of hair sheep neonates were more closely related to climatic variables than to RT and BW. Thermography proved to be an effective tool to determine body heat loss by radiation in skin of neonate lambs.

Effects of dietary ferulic acid on reproductive function and metabolism of pre-pubertal hairbreed ewes during the anestrous season.

This study aimed to evaluate the effects of dietary supplementation of ferulic acid (FA) on reproductive tract weight (RTW), ovarian activity and serum concentrations of some metabolites and thyroid hormones of pre-pubertal hairbreed ewe lambs during the natural anestrous season. Twenty Dorper x Pelibuey crossbred ewe lambs (initial body weight = 28.5 ±â€¯0.5 kg and age = 5.0 mo) were fed a basal diet and assigned to two treatments (n = 10) under randomized complete block design: FA supplementation to dosages of 0 (control) or 300 mg of FA/d animal-1. Females were treated with FA during 34 d and then slaughtered to evaluate RTW and ovary. Blood samples were collected at days 1 and 34 to determine serum concentrations of metabolites (i.e. glucose, cholesterol, triglycerides, urea and total protein) and thyroid hormones. Final weight, dry matter intake, and serum concentrations of metabolites (except glucose) and thyroid hormones were unaltered by FA. Compared to control, FA-fed ewe lambs had lower (P = 0.05) serum glucose level but higher (P ≤ 0.05) RTW, ovarian mass, number of larger follicles and corpus luteum (CL). While percentage of ewe lambs with small follicles and number of small follicles per female did not vary, percentage of ewe lambs with large follicles and CL increased (P = 0.02) with FA. In conclusion, FA supplementation improves the reproductive tract development and ovarian activity of pre-pubertal hairbreed ewe lambs during the natural anestrous season. An improvement in functionality of the glucose-insulin system could be related with this benefic effect of FA.

[Evaluation of the prevalence of HIV infection in prison inmates at the time of their imprisonment during the period 1991-1995]. / Evolución de la prevalencia de infección por virus de la inmunodeficiencia humana en población reclusa al ingreso en prisión durante el período 1991-1995.

BACKGROUND: Inmates of Spanish prisons include a high number of intravenous drug users (IVDUs) and other people whose practices entail the risk of infection with the human immunodeficiency virus (HIV). The aim of this work is to find out the evolution of the prevalence of HIV infection at the time of admission to prison and the factors associated with it in this population group. This may enable us to form an idea of the effectiveness of risk reduction strategies and help to improve them. METHODS: All those people who were placed in a provincial penal institution in the northwest of Spain between 1991 and 1995. Socio-demographic, penal and HIV risk factor variables were gathered. The HIV infection test (ELISA and Western-blot) was carried out with the consent of the subjects. RESULTS: Of the 1,663 people studied, 19.4% were HIV-positive. The prevalence HIV infection was particularly marked statistically in: women (26.0%), the 25-34 age group (29.1%), whites (20.9%), single people (22.8%), those people with a tattoo (29.9%), those people with a background in self-inflicted injuries (42.2%), IVDUs (46.3%), those who admitted sharing syringes (61.5%) and those with a prison record of one or more years (37.3%). Logistical regression analysis showed the following as predictors of HIV infection: IVDUs, those who went to prison in 1992, women, the 25-34 and 35-44 age group, tattooed men, those with a background in self-inflicted injuries and those with a prison record, of more than one year. The gypsy ethnic group revealed a lower probability of HIV infection. The HIV infection time trend, stratified according to the prison record showed an almost significant drop (P = 0.064). The infection trend per IVDU did not show any modification (P = 0.16). CONCLUSIONS: A high prevalence of HIV infection was detected in a prison located in a region which has not been particularly affected by AIDS. IVDUs and some characteristics that may be related to this population group have an enormous influence on this phenomenon. The time trend for this infection in this population group has decreased through the lower number of IVDUs that are admitted to prison although very high levels of prevalence of the infection were maintained in this group over the five years of the study. It is recommended that risk-reduction programmes in prisons be fostered (methadone maintenance programmes, syringe exchange pilot programmes).