Estimation of milk production in hair ewes by two methods of measurement

ABSTRACT Objective. The objective of the current study was to compare two methods to estimate daily milk production in crossbred hair ewes. Materials and methods. Eight multiparous, crossbred (Pelibuey x Katahdin) lactating hair ewes were used in a completely randomized design with repeated measurements, for 56 days. Ewes were fed ad libitum with a diet based on concentrate. Milk production was estimated twice a week for each ewe by both methods, suckled-hand (SH) and weigh-suckle-weigh (WSW) method. Results. Milk production (p>0.05) means were 1031.9±95.6 and 1119.0±95.6 g/day/ewe for SH and WSW method, respectively. Conclusions. No significant differences (p>0.05) were found between methods for milk yield. RESUMEN Objetivo. El objetivo del presente trabajo fue comparar dos métodos para estimar la producción diaria de leche en ovejas de pelo cruzadas. Materiales y métodos. Se utilizaron ocho ovejas multíparas, cruzadas (Pelibuey x Katahdin) y lactantes, en un diseño completamente al azar, con medidas repetidas, durante 56 días. Las ovejas fueron alimentadas ad libitum con una dieta basada en concentrado. La producción de leche se estimó dos veces a la semana a cada oveja, mediante ambos métodos, el doble pesaje del cordero-ordeño manual de la ovejas (DPC-OMO) y el doble pesaje del cordero (DPC). Resultados. La producción de leche estimada (p>0.05) fue de 1031.9±95.6 y 1119.0±95.6 g/día/ovejas para el DPC-OMO y DPC, respectivamente. Conclusión. No se encontraron diferencias significativas (p>0.05) entre métodos de estimación de la producción de leche

Breeding for Resistance to Infectious Diseases in Small Ruminants

Livestock Production/Industries,

The effect of supplementary light on the productive performmance of dorper lambs fed intensively

Thesis (M. Tech.) - Central University of Technology, Free State, 2010The objective of this research study was to quantify the differences in average daily gain (ADG), back fat thickness (BFT), eye muscle area (EMA), fat thickness (FT) on different body parts, the feed conversion ratio (FCR) and body dimensions (by means of body measurements) of Dorper lambs exposed to supplemented light. For this study 120 Dorper lambs (115 ± 10 days old) weighing (29.76 ± 5.01kg) were used. The lambs were randomly divided into three homogeneous groups (20 castrated and 20 intact males). The three groups were then exposed to different levels of supplemented light at 145 lux (16h, 24h and normal photoperiod). The animals were fed ad libitum with pellets containing 9.5 MJ ME/kg DM and 12% CP in open pens. The animals were weighed every 7 days while ultrasound scanning of the EMA and the BFT was done at the beginning and the end of the 35 day trial. The ADG, FCR and feed intake (FI) were calculated at the end of the trial. Linear body measurements including shoulder height, body length and heart girth were taken at day 1 and day 35 respectively. All the animals were slaughtered at the end of the trail. The carcasses were then weighed, graded and the FT was measured with a caliper. The final results of the study showed that no significant differences between the three treatment groups (consisting of wethers and rams) in terms of body measurements, ultrasound scanning ADG and FCR could be detected. However, a significant difference was found between the wethers and the rams in the whole trial for ADG. The ADG of the rams exposed to 16 hours of supplemented light was significantly better than the normal photoperiod and the 24 hour light supplementation group

Estimation of body weight from body measurements in four breeds of Iranian sheep

The aim of the current study was to identify the relationship between body measurements and body weight in fourbreeds of Iranian sheep (Mehrbani, Zandi, Shaal and Macoei). Measuring of body dimensions such as withers height, chestgirth, body length and hip width were done. Analysis of variance for environmental factors and main effects indicated thatsex effect was significant in all studied breeds (p> 0.05). Moreover, all main effects (withers height, chest girth, body lengthand hip width) were also significantly related to body weight in all four breeds. All investigated body measurements showedhigh phenotypic correlation with body weight. The most lightly correlated trait with body weight was body length, withcorrelation coefficients of more than 0.95. Also correlation of body weight with chest girth in sheep breeds of Mehrabani,Zandi and Macoei were very high (0.97, 0.97 and 0.94 respectively), but lower in Shaal breed (0.88). Withers height showeda high correlation with body weight in Shaal sheep (0.98), while this correlation was lower in other breeds (0.91 to 0.93). Hipwidth in all four breeds had the lowest phenotypic correlation with body weight (0.75 to 0.86). In conclusion, the results ofthis study showed that some body measurements can be used as accurate indicators to predict body weight

Association of DRD2 Single Nucleotide Polymorphism and Fescue Toxicosis in Ruminants

Fescue Toxicosis is a prevalent problem in the Southeastern, United States causing an estimated loss of one billion dollars per year to the livestock industry (Roberts & Andrae, 2010). There has been much research aimed at understanding the grass itself, the endophyte and the ergot alkaloids it produces, as well as its relationship and impacts on consuming animals. Many mitigation plans have been established and have been shown to control the amount of alkaloids subsequent animals are ingesting; however, research is at the tipping point of needing a genetic approach to fescue toxicosis. This research looked into the bovine genome to apply the previously identified Single Nucleotide Polymorphism (SNP) found by Campbell et al. (2014) in the Dopamine (DRD2) gene (rs41749780) to a cow/ calf production setting in order to determine if genotype provided advantages for cows (N=74) consuming toxic fescue during late gestation and the effects on their calves until weaning. Furthermore, the Ovine genome was screened for SNP’s in the DRD2 gene in sheep (N= 57, N=61;, N=22) in a series of experiments and associations of the SNP and grazing toxic tall fescue were analyzed. Since fescue toxicosis can affect all ruminant species, the ovine genome was screened for possible SNP sites in the DRD2 gene, and one SNP (g270a) was located and identified. The objectives of this study presented in Chapter 2, were 1) identify a SNP in the DRD2 gene, and 2) determine if there are any genotypic associations with fescue toxicosis. Results indicated ewes of a particular genotype (G|G) had heavier fetal weights and were able to manipulate circulating hormonal levels during pregnancy. This study warranted further investigation, presented in Chapter 3, concluding a genotypic difference in lamb weight and growth with no associations with the dietary treatment of the ewe through gestation. Therefore, a follow up study was designed to further determine if there is an outperforming genotype when ewes were on the same plain of nutrition in the production setting. Conclusions can be made that the G|G genotyped ewes had no production benefits at birth (P=.180) but lambs tended to be heavier by weaning (P=.059) . These lambs tended to have greater average daily gain (ADG) (P=0.079) when compared to lambs from A|A ewes. It appears the G|G genotype has production advantage for lambs from birth to weaning. Furthermore, Chapter 4 applies SNP rs41749780 to cow/calf pairs during late gestation to weaning consuming E- or E+ forages. Seventy-four Angus-based cows were genotyped for the DRD2 SNP with the objective of investigating the effects of dopamine 2 receptor (DRD2) single nucleotide polymorphism (SNP; rs41749780) and fescue treatment during the last trimester on cow and calf performance. Dam weight, serum prolactin, body condition scores (BCS) and hair coat scores (HCS) were collected every 30 d during the last trimester of gestation. Cows with G|G genotype had greater (P =0.012) amount of rump fat deposition compared to A|A cows. Cows with DRD2 genotype of G|G tended to have lower (P = 0.07) prolactin levels at d 0 and 90 of grazing. Adjusted calf birth and weaning weights did not differ (P\u3e0.23) by fescue pasture type or cow genotype. Milk production was estimated using weigh-suckle-weigh at d 30 post-calving. Fescue pasture type and cow genotype did not alter (P \u3e 0.40) milk production. In evaluation of calf sire, there tended to be an interaction (P = 0.07) between fescue pasture type and cow genotype in calves that were sired by natural service. Results concluded grazing toxic tall fescue during late gestation reduced dam BW, rump fat deposition, and serum prolactin levels but did not alter adjusted birth or weaning weights of all calves born. However when evaluated by calf sire, adjusted birth and weaning weight for natural service sired calves showed that response to grazing E+ fescue during late gestation depended on cow DRD2 genotype. The collection of these studies show the potential for a production advantage for G|G genotypes in sheep flocks. In cattle, it appears there may be a genotypic advantage for calves born to dams of A|A genotypes, however due to a variety of other influences a second year study is warranted in order to develop a deeper understanding

Effects of Cold Exposure on Some Physiological, Productive, and Metabolic Variables in Lactating Dairy Goats

Low winter temperatures in some regions have a negative impact on animal performance, behavior, and welfare. The objective of this study was to evaluate some physiological, metabolic, and lactational responses of dairy goats exposed to cold temperatures for 3 weeks. Eight Murciano-Granadina dairy goats (41.8 kg body weight, 70 days in milk, and 2.13 kg/day milk) were used from mid-January to mid-March. Goats were divided into 2 balanced groups and used in a crossover design with 2 treatments in 2 periods (21 days each, 14 days adaptation and 7 days for measurements). After the first period, goats were switched to the opposite treatment. The treatments included 2 different controlled climatic conditions with different temperature-humidity index (THI) values. The treatments were: thermoneutral conditions (TN; 15 to 20 °C, 45% humidity, THI = 58 to 65), and cold temperature (CT; −3 to 6 °C, 63% humidity, THI = 33 to 46). Goats were fed ad libitum a total mixed ration (70% forage and 30% concentrate) and water was freely available. Goats were milked at 0800 and 1700 h. Dry matter intake, water consumption, rectal temperature, and respiratory rate were recorded daily (days 15 to 21). Body weight was recorded at the start and end of each period. Milk samples for composition were collected on 2 consecutive days (days 20 and 21). Insulin, glucose, non-esterified fatty acids (NEFA), ß-hydroxybutyrate (BHB), cholesterol, and triglycerides were measured in blood on d 21. Compared to TN goats, CT goats had similar feed intake, but lower water consumption (−22 ± 3%), respiratory rate (−5 ± 0.8 breaths/min), and rectal temperature (−0.71 ± 0.26 °C). Milk yield decreased by 13 ± 3% in CT goats, but their milk contained more fat (+13 ± 4%) and protein (+14 ± 5%), and consequently the energy-corrected milk did not vary between TN and CT goats. The CT goats lost 0.64 kg of body weight, whereas TN goats gained 2.54 kg in 21 days. Blood insulin and cholesterol levels were not affected by CT. However, values of blood glucose, NEFA, hematocrit, and hemoglobin increased or tended to increase by CT, whereas BHB and triglycerides decreased. Overall, CT goats produced less but concentrated milk compared to TN goats. Despite similar feed intake and blood insulin levels CT goats had increased blood glucose and NEFA levels. The tendency of increased blood NEFA indicates that CT goats mobilized body fat reserves to cover the extra energy needed for heat production under cold conditions