Empirical algebraic modelling of live weight of Irish dairy cows over lactation

The aim of this study is to derive an equation that has the ability to model live weight of Irish dairy cows over lactation. The data set consisted of 6899 cows from 63 herds, of which 428 were from experimental herds and 6471 cows were from commercial herds. An initial examination focussed on time series techniques, as the data are of a time series nature. Splines were also examined to determine the dimensions of a model required to represent the data. As an incomplete gamma function, which was previously used to model milk yield, has been used in other studies to model live weight, various milk yield models were investigated. Finally, live weight changes between two calvings were modelled as a function of age, days in milk and pregnancy. As multicollinearity was evident in this function, the variance inflation factor was examined and principal component analysis was carried out on the variables responsible for multicollinearity. The proposed live weight model has a better fit than previous models, weak multicollinearity and the residuals are homoskedastic, independent and normally distributed. This live weight model therefore provides an acceptable level of accuracy in representing the shape of the live weight curve for Irish dairy cows and can be easily modified for different environmental scenarios.     

Experimental immune complex glomerulonephritis and the nephrotic syndrome in cats immunised with cationised bovine serum albumin

Membranous nephropathy was induced in four cats by repeated intravenous injections of 120 mg cationic bovine serum albumin (BSA, pI 9.5). All four cats developed diffuse granular deposits of IgG and C3 along the glomerular capillary walls as early as five weeks which persisted until the end of the experiment at 17 weeks. Ultrastructural studies revealed many subepithelial electron dense deposits. Two cats developed severe proteinuria and the nephrotic syndrome characterised by hypoalbuminaemia and oedema. An additional four cats received repeated injections of unmodified native BSA (pI 4.5) and remained basically normal. This is the first report of membranous nephropathy and the nephrotic syndrome in an experimental animal model which, unlike other animal models, is subject to the spontaneously occurring disease.     

The effect of granulosa cells on maturation, fertilization and cleavage in vitro

Addition of granulosa cells (GC) (1.10(6)/ml) affected maturation of non-ovulatory oocytes of cattle and caused delay in nuclear maturation (60.8 versus 35.3 or 37.1 percent). In vitro use of pre-incubated GC in the process of maturation led to higher rates of fertilisation (49.4 versus 25.2 or 21.0 percent) and of cleavage (29.6 versus 13.3 or 9.1 percent). No explanation has yet been found for different oocyte behaviours in response to use of fresh or pre-incubated GC. Transfer of seven embryos from maturation with GC as well as in vitro fertilisation and development to four recipients resulted in the birth of one female calf.     

Sulfur-containing amino acid requirement of rapidly growing steers

Eight ruminally cannulated steers (294 kg, ADG = 1.3 kg/d) were used in a N retention study (8 x 8 latin-square design) to evaluate sulfur-containing (S) amino acid (AA) requirements for growth. Treatments were abomasal infusions of seven levels of L-methionine (0, 3, 6, 9, 12, 15 and 18 g/d) and one level of DL-methionine (6 g/d). All steers were fed a semipurified diet based on ammoniated corn cobs (DMI = 6.56 kg/d) and were abomasally infused with 400 g/d dextrose and 296.4 g/d of crystalline AA that simulated the non-S-AA pattern of casein. Infusion of 3 g/d supplemental L-methionine maximized N retention in steers. Intestinal flows of absorbable S-AA were determined to be 1.89 g/kg DMI. Breakpoint analysis of retained N as a function of total absorbable S-AA yielded a total S-AA requirement of 14.7 g/d. Nitrogen retention for DL-methionine (36.4 g/d) was not different (P greater than .05) from that for 6 g/d L-methionine (38.8 g/d), but because this value was not in the linear response range, the efficacy of DL-methionine in meeting S-AA needs could not be evaluated. Plasma methionine concentrations increased linearly (P less than .05) in response to L-methionine infusion and were greater (P less than .05) for steers infused with 6 g/d DL-methionine (45.3 microM) than for steers receiving 6 g/d L-methionine (30.5 microM). Plasma cystine increased when up to 9 g/d L-methionine was infused.(ABSTRACT TRUNCATED AT 250 WORDS)     

A routine 20-22 days post-service milk progesterone monitoring in dairy cows. Economic evaluation

Three hundred and sixty inseminated Holstein cows were monitored in a controlled trial for low milk progesterone concentration 21-23 days post-breeding. Information about low progesterone cows was given to herdsmen for the experimental group only. Of the cows in the experimental group with milk progesterone of less than or equal to 4.5 ng/ml, 56.0% were inseminated within 2 days of monitoring compared to 28.8% of the control animals. Of the cows reaching the 42-day rectal pregnancy diagnosis, 13.7% and 43.6% were negative for the experimental and the control groups respectively. Inter-service intervals were 34.5 +/- 14.5 days and 44.3 +/- 17.7 days for the experimental and control groups respectively. Pregnancy rates were the same for 264 cows served on routine progesterone monitoring and for 318 cows bred on behavioural oestrus when matched to farm and day of breeding. A gain of US $32.5 (an equivalent of 85 l milk) per lactation for a cow in the monitored herd was established using the data in a model of a 250-cow herd with a total pregnancy goal of 82.4%.     

Pathologic findings and association of Mycobacterium bovis infection with the bovine NRAMP1 gene in cattle from herds with naturally occurring tuberculosis

OBJECTIVE: To determine necropsy and Mycobacterium bovis culture results in cattle from herds with tuberculosis, the role of the bovine NRAMP1 gene in resistance and susceptibility to infection with M bovis, and the association between magnitude of the tuberculous lesions and various types of M bovis isolates. ANIMALS: 61 cattle from herds with tuberculosis in Texas and Mexico. PROCEDURE: 61 cattle were evaluated by necropsy; 59 had positive and 2 had negative caudal fold tuberculin intradermal test (CFT) results. Thirty-three cattle with positive CFT results were genotyped to evaluate polymorphism of the 3' untranslated region of the bovine NRAMP1 gene, using single-stranded conformational analysis, 9 were resistant to M bovis with no tuberculous lesions and negative M bovis culture results, and 24 were susceptible with tuberculous lesions and positive M bovis culture results. Isolates of M bovis were analyzed by restriction fragment length polymorphism (RFLP) on the basis of IS6110 sequences and direct-repeat fingerprinting patterns. RESULTS: 21 (35.6%; 21/59) cattle with positive CFT results had tuberculous lesions or positive culture results; in addition, 1 of 2 cattle with negative CFT results had tuberculous lesions and positive culture results. Tuberculous lesions were most common in the thorax (35/63; 55.5%) and lymphoid tissues of the head (10/63; 15.9%). Tuberculous lesions varied from 1 to 11/animal; 8 of 21 (38.1%) had solitary lesions. Associations were not found between resistance or susceptibility to infection with M bovis and polymorphism in the NRAMP1 gene or between the magnitude of the lesions and various RFLP types of M bovis isolates. CONCLUSIONS AND CLINICAL RELEVANCE: The NRAMP1 gene does not determine resistance and susceptibility to infection with M bovis in cattle.     

Effect of different types of litter material for rearing broilers

1. Coir dust was evaluated as broiler litter in comparison with sawdust and rice husk using 135 commercial broilers. Forty-five broiler chicks were reared to 42 d on a 50 mm layer of each of these litters. 2. Birds reared on coir dust showed no difference in food consumption, body weight gain, food conversion efficiency production number and survivability in comparison to those reared on saw dust and rice husk. 3. It was concluded that coir dust is suitable as broiler litter when cheaply available.