Histological and physical-mechanical characteristics of the skin of Dorper sheep related to residual feed intake and the confinement environment

Effect of quantitative feed restriction and sex class on sheep skin quality

The aim was to evaluate the quality of the sheep skin of different sex classes submitted to different levels of feed restriction. Sheep without defined racial pattern of different sex classes (15 non-castrated males, 15 castrated males and 15 females), with initial body weight of 18.1 ± 0.4 kg and mean age of 90 days were distributed in a factorial 3 × 3, with three sex classes and 3 levels of feed restriction (ad libitum intake and restricted intake at 70 and 80%), with 5 repetitions. After slaughter, the skins were collected for physical-mechanical tests. The effect of the sex classes x levels of dietary restriction interaction was observed for transverse thickness and longitudinal rupture elongation (p < 0.05). Animals fed ad libitum had greater longitudinal transverse thickness (p < 0.05). Animals fed ad libitum and 70% feed restriction showed greater transverse elongation at break (p < 0.05). As for the difference between sex classes in the transverse thickness variable for tearing strength, the interaction sex classes x levels of feed restriction for transverse thickness, longitudinal thickness, transverse tearing strength and longitudinal tearing strength occurred (p < 0.05). Feed restriction reduces the physical quality of the skin of sheep of different sex classes, and the use of castrated male sheep in positive energy balance is recommended to obtain leather with greater thickness, longitudinal rupture elongation and transverse tear strength.

Changes in the physiological, hematological and parasitological parameters of Dorper sheep in relation to residual feed intake and confinement environment

The selection of animals with greater feed efficiency has unknown parasitological and physiological parameters when confined in full sun or shade. Thus, we aimed to assess the effect of residual feed intake (RFI) and the confinement environment on the hematological, parasitological and physiological parameters in male Dorper sheep (n = 60; 30 with positive RFI and 30 with negative RFI) distributed in 2 confinement environments (full sun and shade), in a 2 × 2 factorial scheme, with 15 animals for treatment. Animals kept in the shade showed an increase (P < 0.05) of erythrocytes, hemoglobin and albumin. Animals kept in full sun showed higherOocysts gamma glutamyltransferase, direct bilirubin, transaminase aspartate and respiratory rate (P<0.05). There was a higher incidence of Eimeria spp oocysts in RFI negative animals (P<0.05). Positive RFI animals increased respiratory rate (P<0.05). The RFI did not influence the blood parameters of Dorper sheep, however, it had an effect on respiratory rate and presence of Eimeria spp. oocysts. Thermal environment promoted changes in blood parameters and the physiological parameters of Dorper sheep.

Interaction between residual feed intake and thermal environment on performance, nitrogen balance, ingestive behavior and carcass yield of dorper lambs

Residual feed intake (RFI) is a nutritional variable used in genetic improvement programs, the relationship between the environment and the availability of energy and protein in the diet has not yet been explored. Thus, the aim was to evaluate interactions between RFI and thermal environment on performance, nitrogen balance, ingestive behavior and carcass yield of Dorper lambs receiving diets containing different concentrate levels. Dorper lambs (male, n = 64, 17.83 ± 2.43 kg and 110 ± 10 days of age) were confined individually for 40 days for RFI classification. Lambs were separated into positive RFI (n = 30) and negative RFI (n = 30) and remained confined for another 60 days. The animals were distributed in a randomized block design, with a 2 × 2 × 3 factorial scheme, with 2 confinement environments (full sun or shade), 2 groups of feed efficiency (RFI positive or RFI negative) and three diets containing different concentrate levels (30, 45 and 60%), with 5 replications in each treatment. Isolated effects of concentrate level were observed for dry matter intake and digestibility, feeding, rumination, idle and chewing times, feeding efficiency, ingested, excreted and absorbed nitrogen, and on cooling losses, hot and cold carcass yield (P < 0.05). There was an effect of environment × concentrate interaction on performance, retained nitrogen and nitrogen balance (P < 0.05). There was an effect of RFI × environment interaction on the dry matter rumination efficiency, hot and cold carcass weight (P < 0.05). Under experimental conditions, RFI did not influence the productive performance of Dorper lambs. Interactions between environment and diet indicate better performance for Dorper lamb confined in the shade and receiving a higher proportion of concentrate. Animals with negative RFI show better performance and carcass weight when confined in shade, while animals with positive RFI showed better responses to these variables when confined in full sun.

Non-invasive methods to quantify the carcass parameters of sheep: Interaction between thermal environment and residual feed intake

The thermal environment is important in unit production because the perception of thermal stress can reduce fertility, and productive performance, therefore its management is necessary. The use of non-invasive methods, such as infrared thermography and real-time ultrasonography, are widely used to evaluate indicators in animal production, without the need to slaughter the animals. Thus, we aimed to assess the effect of the thermal environment on the physiological parameters and carcass characteristics of Dorper sheep with positive and negative residual feed intake (RFI) using infrared thermography and real-time ultrasonography techniques. Twenty uncastrated male Dorper sheep (17.8 ± 2.4 kg) were confined for 40 days for RFI classification. Sheep were separated into positive RFI (n = 10) and negative RFI (n = 10). The experimental design was in randomized blocks, in a 2 × 2 factorial arrangement, with 2 thermal environments (full sun or shade) and two feed efficiency groups (positive RFI or negative RFI), with 5 replications. The sheep remained in confinement for 60 days. The animals were slaughtered at the end of the experiment and the carcasses dissected for tissue separation. Rectal temperature (RT) and respiratory rate (RR) were measured at two times (14:00 h and 18:00 h) for periods of 5 days. The RR was determined by indirect auscultation of heart sounds at the level of the laryngotracheal region. The RT was measured introduced a digital clinical thermometer into the animal's rectum. Surface temperature (ST) was obtained using a thermographic infrared camera, collecting the temperatures of the eyeball and skin surface in the regions of the head, ribs, rump, flank and shin. Sheep confined in full sun showed higher RR (P = 0.0001), ST ribs (P = 0.0020), ST rumb (P = 0.0055), ST flank (P = 0.0001) and heat tolerance coefficient (HTC) (P = 0.0010). For sheep confined in full sun, a strong correlation was observed between the RR and the mean ST (MST; r = 0.6826; P = 0.0236) and between the final loin eye area (LEAf) with the real LEA (LEAr) (r = 0.9263; P = 0.0001) and slaughter body weight (SBW) (r = 0.7532; P = 0.0325). For negative RFI sheep, a positive correlation was observed between the RR and the ST rump (r = 0.7343; P = 0.0025) and ST ribs (r = 0.6560; P = 0.0178) and the MST (r = 0.7435; P = 0.0001), between the MST and the LEAr (r = 0.6837; P = 0.0025) and the final LEA (r = 0.6771; P = 0.0144), and between the final LEA and LEAr (r = 0.9942; P = 0.0001), BW (r = 0.8415; P = 0.0277) and MST (r = 0.6771; P = 0.0045). Positive RFI sheep confined to shade showed a high correlation between final LEA and LEAr (r = 0.9372; P = 0.0001). The use of shading in confined Dorper sheep, regardless of the RFI classification, reduces the effects of heat stress on physiological parameters.

Bioclimatic Zoning for Sheep Farming through Geostatistical Modeling in the State of Pernambuco, Brazil

The Intergovernmental Panel on Climate Change (IPCC) has pointed out the high vulnerability of developing countries to climate change, which is expected to impact food and income security. Sheep farming is one of the main animal productions among the families located in the most vulnerable regions of the semiarid region of Pernambuco state, a Brazilian territory known for its high temperatures, low relative humidity, and high net solar radiation. Therefore, the objective of this study was to identify different regions of Pernambuco that may be more suitable for different breeds of sheep, based on non-parametric statistics and kriging maps of the temperature and humidity index (THI). THI values were determined based on mean annual temperature and wind speed extracted from the TerraClimate remote sensing database. Pernambuco state presented THI values ranging from 66 to 79, with the hair breeds having a high potential for exploitation in almost all territories, including the main meat-producing breeds. The East Friesian breed, a high milk producer, would be well suited to the Agreste mesoregion, a territory that, like the Pajeú and Moxotó microregions, also proved favorable for the introduction of three wool breeds (Suffolk, Poll Dorset, and Texel) known as major meat producers. The kriging maps of the THI values successfully allowed the identification of strategic development regions of Pernambuco state with high potential for sheep breeding.